2024

Jump to: 2023, 2022, 2021, 2020

17 pages, 3940 KiB

Open AccessArticle

Diversity of the Maize Root Endosphere and Rhizosphere Microbiomes Modulated by the Inoculation with Pseudomonas fluorescens UM270 in a Milpa System

by Blanca Rojas-Sánchez, Hugo Castelán-Sánchez, Esmeralda Y. Garfias-Zamora and Gustavo Santoyo

Plants 2024, 13(7), 954; https://doi.org/10.3390/plants13070954 - 26 Mar 2024

Viewed by 882

Abstract

Milpa is an agroecological production system based on the polyculture of plant species, with corn featuring as a central component. Traditionally, the milpa system does not require the application of chemicals, and so pest attacks and poor growth in poor soils can have [...] Read more.

Milpa is an agroecological production system based on the polyculture of plant species, with corn featuring as a central component. Traditionally, the milpa system does not require the application of chemicals, and so pest attacks and poor growth in poor soils can have adverse effects on its production. Therefore, the application of bioinoculants could be a strategy for improving crop growth and health; however, the effect of external inoculant agents on the endemic microbiota associated with corn has not been extensively studied. Here, the objective of this work was to fertilize a maize crop under a milpa agrosystem with the PGPR Pseudomonas fluorescens UM270, evaluating its impact on the diversity of the rhizosphere (rhizobiome) and root endophytic (root endobiome) microbiomes of maize plants. The endobiome of maize roots was evaluated by 16S rRNA and internal transcribed spacer region (ITS) sequencing, and the rhizobiome was assessed by metagenomic sequencing upon inoculation with the strain UM270. The results showed that UM270 inoculation of the rhizosphere of P. fluorescens UM270 did not increase alpha diversity in either the monoculture or milpa, but it did alter the endophytic microbiome of maize plant roots by stimulating the presence of bacterial operational taxonomic units (OTUs) of the genera Burkholderia and Pseudomonas (in a monoculture), whereas, in the milpa system, the PGPR stimulated greater endophytic diversity and the presence of genera such as Burkholderia, Variovorax, and N-fixing rhizobia genera, including Rhizobium, Mesorhizobium, and Bradyrhizobium. No clear association was found between fungal diversity and the presence of strain UM270, but beneficial fungi, such as Rizophagus irregularis and Exophiala pisciphila, were detected in the Milpa system. In addition, network analysis revealed unique interactions with species such as Stenotrophomonas sp., Burkholderia xenovorans, and Sphingobium yanoikuyae, which could potentially play beneficial roles in the plant. Finally, the UM270 strain does not seem to have a strong impact on the microbial diversity of the rhizosphere, but it does have a strong impact on some functions, such as trehalose synthesis, ammonium assimilation, and polyamine metabolism. The inoculation of UM270 biofertilizer in maize plants modifies the rhizo- and endophytic microbiomes with a high potential for stimulating plant growth and health in agroecological crop models. Full article

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25 pages, 4956 KiB

Open AccessArticle

Physiological and Biochemical Aspects of Silicon-Mediated Resistance in Maize against Maydis Leaf Blight

by Luis Felipe Lata-Tenesaca, Marcos José Barbosa Oliveira, Aline Vieira Barros, Bárbara Bezerra Menezes Picanço and Fabrício Ávila Rodrigues

Plants 2024, 13(4), 531; https://doi.org/10.3390/plants13040531 - 15 Feb 2024

Viewed by 709

Abstract

Maydis leaf blight (MLB), caused by the necrotrophic fungus Bipolaris maydis, has caused considerable yield losses in maize production. The hypothesis that maize plants with higher foliar silicon (Si) concentration can be more resistant against MLB was investigated in this study. This [...] Read more.

Maydis leaf blight (MLB), caused by the necrotrophic fungus Bipolaris maydis, has caused considerable yield losses in maize production. The hypothesis that maize plants with higher foliar silicon (Si) concentration can be more resistant against MLB was investigated in this study. This goal was achieved through an in-depth analysis of the photosynthetic apparatus (parameters of leaf gas exchange chlorophyll (Chl) a fluorescence and photosynthetic pigments) changes in activities of defense and antioxidative enzymes in leaves of maize plants with (+Si; 2 mM) and without (−Si; 0 mM) Si supplied, as well as challenged and not with B. maydis. The +Si plants showed reduced MLB symptoms (smaller lesions and lower disease severity) due to higher foliar Si concentration and less production of malondialdehyde, hydrogen peroxide, and radical anion superoxide compared to −Si plants. Higher values for leaf gas exchange (rate of net CO₂ assimilation, stomatal conductance to water vapor, and transpiration rate) and Chl a fluorescence (variable-to-maximum Chl a fluorescence ratio, photochemical yield, and yield for dissipation by downregulation) parameters along with preserved pool of chlorophyll a+b and carotenoids were noticed for infected +Si plants compared to infected −Si plants. Activities of defense (chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase, polyphenoloxidase, peroxidase, and lipoxygenase) and antioxidative (ascorbate peroxidase, catalase, superoxide dismutase, and glutathione reductase) enzymes were higher for infected +Si plants compared to infected −Si plants. Collectively, this study highlights the importance of using Si to boost maize resistance against MLB considering the more operative defense reactions and the robustness of the antioxidative metabolism of plants along with the preservation of their photosynthetic apparatus. Full article

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22 pages, 1743 KiB

Open AccessReview

Microbiome-Mediated Strategies to Manage Major Soil-Borne Diseases of Tomato

by Shweta Meshram and Tika B. Adhikari

Plants 2024, 13(3), 364; https://doi.org/10.3390/plants13030364 - 25 Jan 2024

Viewed by 1239

Abstract

The tomato (Solanum lycopersicum L.) is consumed globally as a fresh vegetable due to its high nutritional value and antioxidant properties. However, soil-borne diseases can severely limit tomato production. These diseases, such as bacterial wilt (BW), Fusarium wilt (FW), Verticillium wilt (VW), [...] Read more.

The tomato (Solanum lycopersicum L.) is consumed globally as a fresh vegetable due to its high nutritional value and antioxidant properties. However, soil-borne diseases can severely limit tomato production. These diseases, such as bacterial wilt (BW), Fusarium wilt (FW), Verticillium wilt (VW), and root-knot nematodes (RKN), can significantly reduce the yield and quality of tomatoes. Using agrochemicals to combat these diseases can lead to chemical residues, pesticide resistance, and environmental pollution. Unfortunately, resistant varieties are not yet available. Therefore, we must find alternative strategies to protect tomatoes from these soil-borne diseases. One of the most promising solutions is harnessing microbial communities that can suppress disease and promote plant growth and immunity. Recent omics technologies and next-generation sequencing advances can help us develop microbiome-based strategies to mitigate tomato soil-borne diseases. This review emphasizes the importance of interdisciplinary approaches to understanding the utilization of beneficial microbiomes to mitigate soil-borne diseases and improve crop productivity. Full article

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2023

Jump to: 2024, 2022, 2021, 2020

13 pages, 626 KiB

Open AccessArticle

Host Suitability of Lettuce and Bean Germplasm for Meloidogyne incognita and M. javanica Isolates from Spain

by Ariadna Giné, Anna Sanz-Prieto, Luiz Antonio Augusto Gomes, Alejandro Expósito, Nuria Escudero and Francisco Javier Sorribas

Plants 2024, 13(1), 38; https://doi.org/10.3390/plants13010038 - 21 Dec 2023

Viewed by 593

Abstract

Meloidogyne spp. are an important threat to horticulture and cause substantial yield losses. Plant resistance is an alternative control method for chemical nematicides. This study highlights the host suitability of the lettuces cultivars Grand Rapids and Salinas 88 and the beans cultivars Aporé, [...] Read more.

Meloidogyne spp. are an important threat to horticulture and cause substantial yield losses. Plant resistance is an alternative control method for chemical nematicides. This study highlights the host suitability of the lettuces cultivars Grand Rapids and Salinas 88 and the beans cultivars Aporé, Cornell 49242, Macarrão Atibaia and Ouro Negro to four Meloidogyne incognita and seven M. javanica isolates from Spain in a pot experiment. Moreover, the response of these cultivars to increasing M. incognita densities (Pi) was assessed in a plastic greenhouse. The lettuce cultivar Regina 71 and the bean cultivar Bolinha were included as susceptible standards for comparison. It was found that Grand Rapids and Salinas 88 lettuces were resistant to the most nematode isolates in the pot experiment but were classified as slightly and moderately resistant, respectively, in the plastic greenhouse at increasing Pi. Regarding the beans, Aporé was resistant to the majority of the Meloidogyne isolates whereas Macarrão Atibaia and Ouro Negro were slightly resistant and Cornell 49242 was susceptible in the pot experiment. In the plastic greenhouse, Aporé was the only cultivar able to effectively suppress the nematode reproduction irrespective of Pi, while Ouro Negro became less resistant as Pi increased. These results play an important role in enhancing the effective and ecofriendly Meloidogyne management strategies. Full article

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24 pages, 489 KiB

Open AccessReview

Plant-Associated Bacillus thuringiensis and Bacillus cereus: Inside Agents for Biocontrol and Genetic Recombination in Phytomicrobiome

by Antonina Sorokan, Venera Gabdrakhmanova, Zilya Kuramshina, Ramil Khairullin and Igor Maksimov

Plants 2023, 12(23), 4037; https://doi.org/10.3390/plants12234037 - 30 Nov 2023

Cited by 1 | Viewed by 1183

Abstract

Bacillus thuringiensis Berliner (Bt) and B. cereus sensu stricto Frankland and Frankland are closely related species of aerobic, spore-forming bacteria included in the B. cereus sensu lato group. This group is one of the most studied, but it remains also the [...] Read more.

Bacillus thuringiensis Berliner (Bt) and B. cereus sensu stricto Frankland and Frankland are closely related species of aerobic, spore-forming bacteria included in the B. cereus sensu lato group. This group is one of the most studied, but it remains also the most mysterious species of bacteria. Despite more than a century of research on the features of these ubiquitous bacteria, there are a lot of questionable issues related to their taxonomy, resistance to external influences, endophytic existence, their place in multidimensional relationships in the ecosystem, and many others. The review summarizes current data on the mutualistic relationships of Bt and B. cereus bacteria with plants, the structure of the phytomicrobiomes including Bt and B. cereus, and the abilities of plant-associated and endophytic strains to improve plant resistance to various environmental factors and its productivity. Key findings on the possibility of the use of Cry gene promoter for transcription of the target dsRNA and simultaneous release of pore-forming proteins and provocation of RNA-interference in pest organisms allow us to consider this group of microorganisms as unique tools of genetic engineering and biological control. This will open the prospects for the development and direct change of plant microbiomes, and possibly serve as the basis for the regulation of the entire agroecosystem. Full article

17 pages, 10377 KiB

Open AccessArticle

Do Traits Travel? Multiple-Herbicide-Resistant A. tuberculatus, an Alien Weed Species in Israel

by Idan S. Roth, Aviv Singer, Inon Yadid, Moshe Sibony, Zvi Peleg and Baruch Rubin

Plants 2023, 12(23), 4002; https://doi.org/10.3390/plants12234002 - 28 Nov 2023

Viewed by 745

Abstract

Amaranthus tuberculatus is the most common weed in soybean and corn in the USA and Canada. In Israel, it has been a minor riverbank weed. However, in recent years, growing densities of this plant have been observed in field crops, orchards, and roadsides. [...] Read more.

Amaranthus tuberculatus is the most common weed in soybean and corn in the USA and Canada. In Israel, it has been a minor riverbank weed. However, in recent years, growing densities of this plant have been observed in field crops, orchards, and roadsides. Between 2017 and 2022, we surveyed the distribution of A. tuberculatus and collected seeds for further study. We identified three main distribution zones in Israel: the Jezreel Valley, Hula Valley, and Coastal Plain. Most of the populations were found near water sources, fishponds, barns, dairies, or bird-feeding sites, suggesting the involvement of imported grain in introducing A. tuberculatus to Israel. Populations were screened for their responses to various post-emergence herbicides (i.e., ALS, EPSPS, PPO, HPPD, and PSII inhibitors). Several populations from the Jezreel Valley were found to be putatively resistant to ALS, EPSPS, and PPO inhibitors. The responses of those populations to trifloxysulfuron, glyphosate, and carfentrazone-ethyl were also studied. A single ALS-, EPSPS- and PPO-resistant plant was vegetatively propagated to create a clonal population, which was treated with foramsulfuron, glyphosate, and carfentrazone-ethyl. No resistance to PSII or HPPD inhibitors was observed, but resistance to herbicides that inhibit ALS, EPSPS, and PPO was observed. A clonal propagation assay revealed the existence of a population that was resistant to ALS, EPSPS, and PPO inhibitors. Since the local A. tuberculatus populations have not been exposed to herbicide selection pressure, these traits probably reached Israel through seed-mediated gene flow via imported grain. Full article

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20 pages, 5645 KiB

Open AccessArticle

First Report of Fungal Pathogens Causing Leaf Spot on Sorghum–Sudangrass Hybrids and Their Interactions with Plants

by Junying Li, Jingxuan Xu, Hongji Wang, Changfeng Wu, Jiaqi Zheng, Chaowen Zhang and Yuzhu Han

Plants 2023, 12(17), 3091; https://doi.org/10.3390/plants12173091 - 29 Aug 2023

Cited by 1 | Viewed by 1037

Abstract

The sorghum–sudangrass hybrid is the main high-quality forage grass in Southwest China, but, in recent years, it has suffered from leaf spot disease, with a prevalence of 88% in Bazhong, Sichuan, China, seriously affecting yield and quality. The causal agents were obtained from [...] Read more.

The sorghum–sudangrass hybrid is the main high-quality forage grass in Southwest China, but, in recent years, it has suffered from leaf spot disease, with a prevalence of 88% in Bazhong, Sichuan, China, seriously affecting yield and quality. The causal agents were obtained from symptomatic leaves by tissue isolation and verified by pathogenicity assays. A combination of morphological characterization and sequence analysis revealed that strains SCBZSL1, SCBZSX5, and SCBZSW6 were Nigrospora sphaerica, Colletotrichum boninense, and Didymella corylicola, respectively, and the latter two were the first instance to be reported on sorghum–sudangrass hybrids in the world. SCBZSX5 significantly affected the growth of the plants, which can reduce plant height by 25%. The biological characteristics of SCBZSX5 were found to be less sensitive to the change in light and pH, and its most suitable culture medium was Potato Dextrose Agar (PDA), with the optimal temperature of 25 °C and lethal temperature of 35 °C. To clarify the interactions between the pathogen SCBZSX5 and plants, metabolomics analyses revealed that 211 differential metabolites were mainly enriched in amino acid metabolism and flavonoid metabolism. C. boninense disrupted the osmotic balance of the plant by decreasing the content of acetyl proline and caffeic acid in the plant, resulting in disease occurrence, whereas the sorghum–sudangrass hybrids improved tolerance and antioxidant properties through the accumulation of tyrosine, tryptophan, glutamic acid, leucine, glycitein, naringenin, and apigetrin to resist the damage caused by C. boninense. This study revealed the mutualistic relationship between sorghum–sudangrass hybrids and C. boninense, which provided a reference for the control of the disease. Full article

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15 pages, 895 KiB

Open AccessArticle

Characterization of the Virulence and Yield Impact of Fusarium Species on Canola (Brassica napus)

by Haitian Yu, Kan-Fa Chang, Sheau-Fang Hwang and Stephen E. Strelkov

Plants 2023, 12(17), 3020; https://doi.org/10.3390/plants12173020 - 22 Aug 2023

Cited by 1 | Viewed by 849

Abstract

Multiple species of Fusarium can contribute to the development of root rot in canola (Brassica napus), making disease management difficult. We conducted field and greenhouse experiments to investigate the impacts of Fusarium avenaceum and Fusarium proliferatum, and the interaction between [...] Read more.

Multiple species of Fusarium can contribute to the development of root rot in canola (Brassica napus), making disease management difficult. We conducted field and greenhouse experiments to investigate the impacts of Fusarium avenaceum and Fusarium proliferatum, and the interaction between Fusarium oxysporum and F. proliferatum on root rot severity and canola yields. Inoculation with any of the three Fusarium spp. resulted in significant disease severity and reduced seedling emergence compared with non-inoculated controls, leading to yield reductions of up to 35%. Notably, there was a strong correlation (r = 0.93) between root rot severity at the seedling stage and at maturity. Regression analysis indicated a linear decline in seedling emergence with increasing disease severity. Furthermore, disease severity at maturity adversely affected the pod number per plant and the seed weight per plant, with both parameters ultimately approaching zero at a severity of 4.0 on a 0–4 scale. Co-inoculation with F. oxysporum and F. proliferatum induced more severe root rot than inoculation with each species on its own, suggesting synergistic interactions between these fungi. Knowledge of these interactions and the relative virulence of Fusarium spp. will contribute to the improved management of root rot in canola. Full article

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15 pages, 2886 KiB

Open AccessArticle

Effect of Soil and Root Extracts on the Innate Immune Response of American Ginseng (Panax quinquefolius) to Root Rot Caused by Ilyonectria mors-panacis

by Behrang Behdarvandi and Paul H. Goodwin

Plants 2023, 12(13), 2540; https://doi.org/10.3390/plants12132540 - 04 Jul 2023

Viewed by 843

Abstract

Panax quinquefolius shows much higher mortality to Ilyonectria mors-panacis root rot when grown in soil previously planted with ginseng than in soil not previously planted with ginseng, which is known as ginseng replant disease. Treatment of ginseng roots with methanol extracts of previous [...] Read more.

Panax quinquefolius shows much higher mortality to Ilyonectria mors-panacis root rot when grown in soil previously planted with ginseng than in soil not previously planted with ginseng, which is known as ginseng replant disease. Treatment of ginseng roots with methanol extracts of previous ginseng soils significantly increased root lesion sizes due to I. mors-panacis compared to roots treated with water or methanol extracts of ginseng roots or non-ginseng soils. Inoculation of water-treated roots with I. mors-panacis increased expression of a basic chitinase 1 gene (PqChi-1), neutral pathogenesis-related protein 5 gene (PqPR5) and pathogenesis-related protein 10-2 gene (PqPR10-2), which are related to jasmonic acid (JA), ethylene (ET) or necrotrophic infection, and also increased expression of an acidic β-1-3-glucanase gene (PqGlu), which is related to salicylic acid (SA). Infection did not affect expression of a cysteine protease inhibitor gene (PqCPI). Following infection, roots treated with ginseng root extract mostly showed similar expression patterns as roots treated with water, but roots treated with previous ginseng soil extract showed reduced expression of PqChi-1, PqPR5, PqPR10-2 and PqCPI, but increased expression of PqGlu. Methanol-soluble compound(s) in soil previously planted with ginseng are able to increase root lesion size, suppress JA/ET-related gene expression and trigger SA-related gene expression in ginseng roots during I. mors-panacis infection, and may be a factor contributing to ginseng replant disease. Full article

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15 pages, 2797 KiB

Open AccessArticle

Factors Affecting the Germination Ecology of Pimelea trichostachya and Its Relationship to Field Emergence

by Rashid Saleem, Shane Campbell, Mary T. Fletcher, Sundaravelpandian Kalaipandian and Steve Adkins

Plants 2023, 12(11), 2112; https://doi.org/10.3390/plants12112112 - 26 May 2023

Cited by 1 | Viewed by 1187

Abstract

Pimelea trichostachya Lindl is a little-understood Australian native plant, with irregular field emergence, causing significant poisoning to grazing livestock. The study aims to examine the form of dormancy exhibited by P. trichostachya and determine how key environmental conditions, such as alternating temperature and [...] Read more.

Pimelea trichostachya Lindl is a little-understood Australian native plant, with irregular field emergence, causing significant poisoning to grazing livestock. The study aims to examine the form of dormancy exhibited by P. trichostachya and determine how key environmental conditions, such as alternating temperature and light conditions, moisture availability, substrate pH and burial depth, affect its germination and emergence. The study concludes that P. trichostachya has a complex dormancy mechanism. This comprises a physical component that can be partly removed by fruit scarification, a metabolic dormancy that can be overcome by gibberellic acid (GA₃), and a suspected third mechanism based on a water-soluble germination inhibitor. The results showed that scarified single seeded fruit (hereafter seed) with GA₃ treatment gave the highest germination percentage (86 ± 3%) at 25/15 °C, with good germination rates at other temperature regimes. Light exposure stimulated germination, but a significant proportion of seeds still germinated in the dark. The study also found that seeds could germinate under water-limited conditions and a wide range of pH levels (4 to 8). Seedling emergence was inhibited when seeds were buried below 3 cm in soil. Pimelea trichostachya emergence in the field commonly occurs from Autumn to Spring. Understanding its dormancy mechanism and recognizing its triggers for germination will enable better prediction of outbreaks. This can help landholders prepare for emergence and help manage seedbank build-up in pastures and crops. Full article

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20 pages, 3987 KiB

Open AccessArticle

Impacts of Myrtle Rust Induced Tree Mortality on Species and Functional Richness within Seedling Communities of a Wet Sclerophyll Forest in Eastern Australia

by Kristy Stevenson, Geoff Pegg, Jarrah Wills, John Herbohn and Jennifer Firn

Plants 2023, 12(10), 1970; https://doi.org/10.3390/plants12101970 - 12 May 2023

Viewed by 1427

Abstract

Austropuccinia psidii is an introduced plant pathogen known to have caused significant declines in populations of several Australian native Myrtaceae species. However, limited research has focused on the impacts of the pathogen on plant communities in the aftermath of its invasion. This study [...] Read more.

Austropuccinia psidii is an introduced plant pathogen known to have caused significant declines in populations of several Australian native Myrtaceae species. However, limited research has focused on the impacts of the pathogen on plant communities in the aftermath of its invasion. This study investigated the relationship between disease impact level, plant species diversity, and functional richness in seedling communities in a wet sclerophyll forest in southeast Queensland. A clear shift was found from early colonizer Myrtaceae species in the mid- and understory to a more diverse non-Myrtaceae seedling community indicative of secondary succession. Comparisons of key Myrtaceae species and the seedling community suggest that there may also be a shift towards species that produce drupes and larger seeds, and overall, a current reduction in fruit availability due to the dramatic loss of previously dominant species. Seedling diversity showed no significant correlation with tree mortality, possibly due to favorable rainfall conditions during the study period. The more subtle changes in forest composition, such as changes in fruit type and availability due to myrtle rust, however, could affect the visitation of local bird species in the short term and certainly reduce the store of early colonizing native shrub and tree species. Full article

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16 pages, 1257 KiB

Open AccessArticle

Aggressiveness and Patulin Production in Penicillium expansum Multidrug Resistant Strains with Different Expression Levels of MFS and ABC Transporters, in the Presence or Absence of Fludioxonil

by Panagiota Ntasiou, Anastasios Samaras, Emmanouil-Nikolaos Papadakis, Urania Menkissoglu-Spiroudi and George S. Karaoglanidis

Plants 2023, 12(6), 1398; https://doi.org/10.3390/plants12061398 - 21 Mar 2023

Cited by 3 | Viewed by 1705

Abstract

Penicillium expansum is the most common postharvest pathogen of apple fruit, causing blue mold disease. Due to the extensive use of fungicides, strains resistant to multiple chemical classes have been selected. A previous study by our group proposed that the overexpression of MFS [...] Read more.

Penicillium expansum is the most common postharvest pathogen of apple fruit, causing blue mold disease. Due to the extensive use of fungicides, strains resistant to multiple chemical classes have been selected. A previous study by our group proposed that the overexpression of MFS (major facilitator superfamily) and ABC (ATP binding cassette) transporters constitute an alternative resistance mechanism in Multi Drug resistant (MDR) strains of this pathogen. This study was initiated to determine two main biological fitness parameters of MDR strains: aggressiveness against apple fruit and patulin production. In addition, the expression pattern of efflux transporters and hydroxylase-encoding genes that belong to the patulin biosynthesis pathway, in the presence or absence of fludioxonil and under in vitro and in vivo conditions were investigated. Results showed that the MDR strains produced higher concentrations of patulin but showed a lower pathogenicity compared to the wild-type isolates. Moreover, expression analysis of patC, patM and patH genes indicated that the higher expression levels do not correlate with the detected patulin concentration. The selection of MDR strains in P. expansum populations and the fact that they produce more patulin, constitutes a serious concern not only for successful disease control but also for human health. The above-mentioned data represent the first report of MDR in P. expansum associated with its patulin-production ability and the expression level of patulin biosynthesis pathway genes. Full article

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16 pages, 3430 KiB

Open AccessArticle

The Current and Potential Distribution of Parthenium Weed and Its Biological Control Agent in Pakistan

by Asad Shabbir, Myron P. Zalucki, Kunjithapatham Dhileepan, Naeem Khan and Steve W. Adkins

Plants 2023, 12(6), 1381; https://doi.org/10.3390/plants12061381 - 20 Mar 2023

Cited by 5 | Viewed by 2608

Abstract

Parthenium hysterophorus L. (Asteraceae), commonly known as parthenium weed, is a highly invasive weed spreading rapidly from northern to southern parts of Pakistan. The persistence of parthenium weed in the hot and dry southern districts suggests that the weed can survive under more [...] Read more.

Parthenium hysterophorus L. (Asteraceae), commonly known as parthenium weed, is a highly invasive weed spreading rapidly from northern to southern parts of Pakistan. The persistence of parthenium weed in the hot and dry southern districts suggests that the weed can survive under more extreme conditions than previously thought. The development of a CLIMEX distribution model, which considered this increased tolerance to drier and warmer conditions, predicted that the weed could still spread to many other parts of Pakistan as well as to other regions of south Asia. This CLIMEX model satisfied the present distribution of parthenium weed within Pakistan. When an irrigation scenario was added to the CLIMEX program, more parts of the southern districts of Pakistan (Indus River basin) became suitable for parthenium weed growth, as well as the growth of its biological control agent, Zygogramma bicolorata Pallister. This expansion from the initially predicted range was due to irrigation producing extra moisture to support its establishment. In addition to the weed moving south in Pakistan due to irrigation, it will also move north due to temperature increases. The CLIMEX model indicated that there are many more areas within South Asia that are suitable for parthenium weed growth, both under the present and a future climate scenario. Most of the south-western and north-eastern parts of Afghanistan are suitable under the current climate, but more areas are likely to become suitable under climate change scenarios. Under climate change, the suitability of southern parts of Pakistan is likely to decrease. Full article

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22 pages, 3083 KiB

Open AccessArticle

Assessment of Black Rot in Oilseed Rape Grown under Climate Change Conditions Using Biochemical Methods and Computer Vision

by Mónica Pineda and Matilde Barón

Plants 2023, 12(6), 1322; https://doi.org/10.3390/plants12061322 - 14 Mar 2023

Cited by 2 | Viewed by 1409

Abstract

Global warming is a challenge for plants and pathogens, involving profound changes in the physiology of both contenders to adapt to the new environmental conditions and to succeed in their interaction. Studies have been conducted on the behavior of oilseed rape plants and [...] Read more.

Global warming is a challenge for plants and pathogens, involving profound changes in the physiology of both contenders to adapt to the new environmental conditions and to succeed in their interaction. Studies have been conducted on the behavior of oilseed rape plants and two races (1 and 4) of the bacterium Xanthomonas campestris pv. campestris (Xcc) and their interaction to anticipate our response in the possible future climate. Symptoms caused by both races of Xcc were very similar to each other under any climatic condition assayed, although the bacterial count from infected leaves differed for each race. Climate change caused an earlier onset of Xcc symptoms by at least 3 days, linked to oxidative stress and a change in pigment composition. Xcc infection aggravated the leaf senescence already induced by climate change. To identify Xcc-infected plants early under any climatic condition, four classifying algorithms were trained with parameters obtained from the images of green fluorescence, two vegetation indices and thermography recorded on Xcc-symptomless leaves. Classification accuracies were above 0.85 out of 1.0 in all cases, with k-nearest neighbor analysis and support vector machines performing best under the tested climatic conditions. Full article

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13 pages, 3697 KiB

Open AccessArticle

Alternative Plant Vitrification Solution A3-80% and Initial Ammonium-Free Regrowth Medium Enable Cryobanking of Chrysanthemum Germplasm

by Hyoeun Lee, Junsun Park, Sang-Un Park and Haenghoon Kim

Plants 2023, 12(5), 1059; https://doi.org/10.3390/plants12051059 - 27 Feb 2023

Cited by 1 | Viewed by 1054

Abstract

Cryopreservation, storing biological material in liquid nitrogen (LN, −196 °C), offers a valuable option for the long-term conservation of non-orthodox seeds and vegetatively propagated species in the sector of agrobiodiversity and wild flora. Although large-scale cryobanking of germplasm collections has been increasing worldwide, [...] Read more.

Cryopreservation, storing biological material in liquid nitrogen (LN, −196 °C), offers a valuable option for the long-term conservation of non-orthodox seeds and vegetatively propagated species in the sector of agrobiodiversity and wild flora. Although large-scale cryobanking of germplasm collections has been increasing worldwide, the wide application of cryopreservation protocol is hampered by a lack of universal cryopreservation protocols, among others. This study established a systematic approach to developing a droplet-vitrification cryopreservation procedure for chrysanthemum shoot tips. The standard procedure includes two-step preculture with 10% sucrose for 31 h and with 17.5% sucrose for 16 h, osmoprotection with loading solution C4-35% (17.5% glycerol + 17.5% sucrose, w/v) for 40 min, cryoprotection with alternative plant vitrification solution A3-80% (33.3% glycerol + 13.3% dimethyl sulfoxide + 13.3% ethylene glycol + 20.1% sucrose, w/v) at 0 °C for 60 min, and cooling and rewarming using aluminum foil strips. After unloading, a three-step regrowth procedure starting with an ammonium-free medium with 1 mg L⁻¹ gibberellic acid (GA₃) and 1 mg L⁻¹ benzyl adenine (BA) followed by an ammonium-containing medium with and without growth regulators was essential for the development of normal plantlets from cryopreserved shoot tips. A pilot cryobanking of 154 accessions of chrysanthemum germplasm initiated with post-cryopreservation regeneration of 74.8%. This approach will facilitate the cryobanking of the largest Asteraceae family germplasm as a complementary long-term conservation method. Full article

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15 pages, 2007 KiB

Open AccessArticle

Soil Fungistasis against Fusarium Graminearum under Different tillage Systems

by Skaidrė Supronienė, Gražina Kadžienė, Arman Shamshitov, Agnė Veršulienė, Donatas Šneideris, Algirdas Ivanauskas and Renata Žvirdauskienė

Plants 2023, 12(4), 966; https://doi.org/10.3390/plants12040966 - 20 Feb 2023

Viewed by 1388

Abstract

The establishment of the harmful pathogen Fusarium graminearum in different agroecosystems may strongly depend on the ability of the soils to suppress its development and survival. This study aimed to evaluate the influence of different soil tillage systems (i.e., conventional tillage, reduced tillage [...] Read more.

The establishment of the harmful pathogen Fusarium graminearum in different agroecosystems may strongly depend on the ability of the soils to suppress its development and survival. This study aimed to evaluate the influence of different soil tillage systems (i.e., conventional tillage, reduced tillage and no-tillage) on soil fungistasis against F. graminearum. Soil samples were collected three times during the plant growing season in 2016 and 2017 from a long-term, 20-year soil tillage experiment. The F. graminearum in the soil samples was quantified by real-time qPCR. The soil fungistasis was evaluated by the reduction in the radial growth of F. graminearum in an in vitro assay. The antagonistic activity of the soil bacteria was tested using the dual culture method. The F. graminearum DNA contents in the soils were negatively correlated with soil fungistasis (r = –0.649 *). F. graminearum growth on the unfumigated soil was reduced by 70–87% compared to the chloroform fumigated soil. After the plant vegetation renewal, the soil fungistasis intensity was higher in the conventionally tilled fields than in the no-tillage. However, no significant differences were obtained among the tillage treatments at the mid-plant growth stage and after harvesting. 23 out of 104 bacteria isolated from the soil had a moderate effect, and only 1 had a strong inhibitory effect on the growth of F. graminearum. This bacterium was assigned 100% similarity to the Bacillus amyloliquefaciens Hy7 strain (gene bank no: JN382250) according to the sequence of the 16S ribosome subunit coding gene. The results of our study suggest that the presence of F. graminearum in soil is suppressed by soil fungistasis; however, the role of tillage is influenced by other factors, such as soil biological activity, type and quantity of plant residues and environmental conditions. Full article

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17 pages, 1704 KiB

Open AccessArticle

Polyethylene Glycol and Sorbitol-Mediated In Vitro Screening for Drought Stress as an Efficient and Rapid Tool to Reach the Tolerant Cucumis melo L. Genotypes

by Maryam Nekoee Mehmandar, Farzad Rasouli, Mousa Torabi Giglou, Seyed Morteza Zahedi, Mohammad Bagher Hassanpouraghdam, Mohammad Ali Aazami, Rana Panahi Tajaragh, Pavel Ryant and Jiri Mlcek

Plants 2023, 12(4), 870; https://doi.org/10.3390/plants12040870 - 15 Feb 2023

Cited by 4 | Viewed by 2549

Abstract

An efficient method to instantly assess drought-tolerant plants after germination is using osmoregulation in tissue culture media. In this study, the responses of three Iranian melon genotypes to sorbitol (0.1, 0.2, and 0.4 M) or polyethylene glycol (PEG) (0.009, 0.012, and 0.015 M) [...] Read more.

An efficient method to instantly assess drought-tolerant plants after germination is using osmoregulation in tissue culture media. In this study, the responses of three Iranian melon genotypes to sorbitol (0.1, 0.2, and 0.4 M) or polyethylene glycol (PEG) (0.009, 0.012, and 0.015 M) were evaluated as drought stress simulators in MS medium. ‘Girke’ (GIR), ‘Ghobadloo’ (GHO), and ‘Toghermezi’ (TOG) were the genotypes. GIR is reputed as a drought-tolerant genotype in Iran. The PEG or sorbitol decreased the coleoptile length, fresh weight, and photosynthetic pigments content while enhancing proline and malondialdehyde (MDA) contents. Protein content and antioxidant enzyme activity were utterly dependent on genotype, osmotic regulators, and their concentration. Coleoptile length, root and shoot fresh weight, root dry weight, proline and MDA content, and guaiacol peroxidase (GPX) activity can be used as indicators for in vitro screening of Cucumis melo L. genotypes. The results showed that sorbitol mimics drought stress better than PEG. Overall, our findings suggest that in vitro screening could be an accurate, rapid, and reliable methodology for evaluating and identifying drought-tolerant genotypes. Full article

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16 pages, 3339 KiB

Open AccessReview

Ruta angustifolia Pers. (Narrow-Leaved Fringed Rue): Pharmacological Properties and Phytochemical Profile

by Christian Bailly

Plants 2023, 12(4), 827; https://doi.org/10.3390/plants12040827 - 13 Feb 2023

Cited by 5 | Viewed by 2681

Abstract

The genus Ruta in the family Rutaceae includes about 40 species, such as the well-known plants R. graveolens L. (common rue) or R. chalepensis L. (fringed rue), but also much lesser-known species such as R. angustifolia Pers. (narrow-leaved fringed rue). This rue specie, [...] Read more.

The genus Ruta in the family Rutaceae includes about 40 species, such as the well-known plants R. graveolens L. (common rue) or R. chalepensis L. (fringed rue), but also much lesser-known species such as R. angustifolia Pers. (narrow-leaved fringed rue). This rue specie, originating from the Mediterranean region, is well-distributed in Southeast Asia, notably in the Indo-Chinese peninsula and other territories. In some countries, such as Malaysia, the plant is used to treat liver diseases and cancer. Extracts of R. angustifolia display antifungal, antiviral and antiparasitic effects. Diverse bioactive natural products have been isolated from the aerial parts of the plant, notably quinoline alkaloids and furocoumarins, which present noticeable anti-inflammatory, antioxidant and/or antiproliferative properties. The present review discusses the main pharmacological properties of the plant and its phytoconstituents, with a focus on the anticancer activities evidenced with diverse alkaloids and terpenoids isolated from the aerial parts of the plant. Quinoline alkaloids such as graveoline, kokusaginine, and arborinine have been characterized and their mode of action defined. Arborinine stands as a remarkable inhibitor of histone demethylase LSD1, endowed with promising anticancer activities. Other anticancer compounds, such as the furocoumarins chalepin and rutamarin, have revealed antitumor effects. Their mechanism of action is discussed together with that of other bioactive natural products, including angustifolin and moskachans. Altogether, R. angustifolia Pers. presents a rich phytochemical profile, fully consistent with the traditional use of the plant to treat cancer. This rue species, somewhat neglected, warrant further investigations as a medicinal plant and a source of inspiration for drug discovery and design. Full article

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18 pages, 2318 KiB

Open AccessArticle

The Distribution of Phytoecdysteroids among Terrestrial Vascular Plants: A Comparison of Two Databases and Discussion of the Implications for Plant/Insect Interactions and Plant Protection

by Laurence Dinan, Françoise Lafont and René Lafont

Plants 2023, 12(4), 776; https://doi.org/10.3390/plants12040776 - 09 Feb 2023

Cited by 1 | Viewed by 1719

Abstract

Phytoecdysteroids are a class of plant secondary compounds which are present in a wide diversity of vascular plant species, where they contribute to a reduction in invertebrate predation. Over the past 55 years, a significant body of heterogeneous literature on the presence, identities [...] Read more.

Phytoecdysteroids are a class of plant secondary compounds which are present in a wide diversity of vascular plant species, where they contribute to a reduction in invertebrate predation. Over the past 55 years, a significant body of heterogeneous literature on the presence, identities and/or quantities of ecdysteroids in plant species has accumulated, resulting in the compilation of a first database, the Ecdybase Literature Survey (ELS; 4908 entries, covering 2842 species). A second extensive database on the distribution of ecdysteroids in vascular plants is available as the Exeter Survey (ES; 4540 entries, covering 4155 species), which used standardised extraction and analysis methods to survey seeds/spores. We compare the usefulness of these two databases to provide information on the occurrence of phytoecdysteroids at the order/family levels in relation to the recent molecular classifications of gymnosperms, pteridophytes/lycophytes and angiosperms. The study, in conjunction with the other published literature, provides insights into the distribution of phytoecdysteroids in the plant world, their role in plant protection in nature and their potential future contribution to crop protection. Furthermore, it will assist future investigations in the chemotaxonomy of phytoecdysteroids and other classes of plant secondary compounds. Full article

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14 pages, 1881 KiB

Open AccessArticle

Canola with Stacked Genes Shows Moderate Resistance and Resilience against a Field Population of Plasmodiophora brassicae (Clubroot) Pathotype X

by Nazmoon Naher Tonu, Rui Wen, Tao Song, Xiaowei Guo, Lee Anne Murphy, Bruce Dean Gossen, Fengqun Yu and Gary Peng

Plants 2023, 12(4), 726; https://doi.org/10.3390/plants12040726 - 06 Feb 2023

Viewed by 1432

Abstract

Genetic resistance is a cornerstone for managing clubroot (Plasmodiophora brassicae). However, when used repeatedly, a clubroot resistance (CR) gene can be broken rapidly. In this study, canola inbred/hybrid lines carrying one or two CR genes (Rcr1/CRa^M and Crr1^rutb [...] Read more.

Genetic resistance is a cornerstone for managing clubroot (Plasmodiophora brassicae). However, when used repeatedly, a clubroot resistance (CR) gene can be broken rapidly. In this study, canola inbred/hybrid lines carrying one or two CR genes (Rcr1/CRa^M and Crr1^rutb) were assessed against P. brassicae pathotype X by repeated exposure to the same inoculum source under a controlled environment. Lines carrying two CR genes, either Rcr1 + Crr1^rutb or CRa^M + Crr1^rutb, showed partial resistance. Selected lines were inoculated with a field pathotype X population (L-G3) at 5 × 10⁶ resting spores/g soil, and all clubs were returned to the soil they came from six weeks after inoculation. The planting was repeated for five cycles, with diseased roots being returned to the soil after each cycle. The soil inoculum was quantified using qPCR before each planting cycle. All lines with a single CR gene were consistently susceptible, maintaining high soil inoculum levels over time. The lines carrying two CR genes showed much lower clubroot severity, resulting in a 10-fold decline in soil inoculum. These results showed that the CR-gene stacking provided moderate resistance against P. brassicae pathotype X, which may also help reduce the pathogen inoculum buildup in soil. Full article

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29 pages, 4881 KiB

Open AccessArticle

Palliating Salt Stress in Mustard through Plant-Growth-Promoting Rhizobacteria: Regulation of Secondary Metabolites, Osmolytes, Antioxidative Enzymes and Stress Ethylene

by Varisha Khan, Shahid Umar and Noushina Iqbal

Plants 2023, 12(4), 705; https://doi.org/10.3390/plants12040705 - 05 Feb 2023

Cited by 12 | Viewed by 2153

Abstract

The severity of salt stress is alarming for crop growth and production and it threatens food security. Strategies employed for the reduction in stress are not always eco-friendly or sustainable. Plant-growth-promoting rhizobacteria (PGPR) could provide an alternative sustainable stress reduction strategy owning to [...] Read more.

The severity of salt stress is alarming for crop growth and production and it threatens food security. Strategies employed for the reduction in stress are not always eco-friendly or sustainable. Plant-growth-promoting rhizobacteria (PGPR) could provide an alternative sustainable stress reduction strategy owning to its role in various metabolic processes. In this study, we have used two strains of PGPR, Pseudomonas fluorescens (NAIMCC-B-00340) and Azotobacter chroococcum Beijerinck 1901 (MCC 2351), either singly or in combination, and studied their effect in the amelioration of salt toxicity in mustard cultivar Pusa Jagannath via its influence on plants’ antioxidants’ metabolism, photosynthesis and growth. Individually, the impact of Pseudomonas fluorescens was better in reducing stress ethylene, oxidative stress, photosynthesis and growth but maximal alleviation was observed with their combined application. MDA and H₂O₂ content as indicator of oxidative stress decreased by 27.86% and 45.18% and osmolytes content (proline and glycine-betaine) increased by 38.8% and 26.3%, respectively, while antioxidative enzymes (SOD, CAT, APX and GR) increased by 58.40, 25.65, 81.081 and 55.914%, respectively, over salt-treated plants through the application of Pseudomonas fluorescens. The combined application maximally resulted in more cell viability and less damage to the leaf with lesser superoxide generation due to higher antioxidative enzymes and reduced glutathione formation (GSH). Considering the obtained results, we can supplement the PGPR in combination to plants subjected to salt stress, prevent photosynthetic and growth reduction, and increase the yield of plants. Full article

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17 pages, 2940 KiB

Open AccessArticle

Hsp90 Gene Is Required for Mi-1-Mediated Resistance of Tomato to the Whitefly Bemisia tabaci

by Susana Pascual, Clara I. Rodríguez-Álvarez, Isgouhi Kaloshian and Gloria Nombela

Plants 2023, 12(3), 641; https://doi.org/10.3390/plants12030641 - 01 Feb 2023

Cited by 3 | Viewed by 1661

Abstract

The Mi-1 gene of tomato (Solanum lycopersicum) confers resistance against some nematodes and insects, but the resistance mechanisms differ depending on the harmful organism, as a hypersensitive reaction (HR) occurs only in the case of nematodes. The gene Rme1 is required [...] Read more.

The Mi-1 gene of tomato (Solanum lycopersicum) confers resistance against some nematodes and insects, but the resistance mechanisms differ depending on the harmful organism, as a hypersensitive reaction (HR) occurs only in the case of nematodes. The gene Rme1 is required for Mi-1-mediated resistance to nematodes, aphids, and whiteflies, and several additional proteins also play a role in this resistance. Among them, the involvement of the chaperone HSP90 has been demonstrated in Mi-1-mediated resistance for aphids and nematodes, but not for whiteflies. In this work, we studied the implication of the Hsp90 gene in the Mi-1 resistance against the whitefly Bemisia tabaci by means of Tobacco rattle virus (TRV)-based virus-induced gene silencing (VIGS). The silencing of the Hsp90 gene in tomato Motelle plants carrying the Mi-1 gene resulted in a decrease in resistance to whiteflies, as oviposition values were significantly higher than those on non-silenced plants. This decrease in resistance was equivalent to that caused by the silencing of the Mi-1 gene itself. Infiltration with the control TRV vector did not alter Mi-1 mediated resistance to B. tabaci. Similar to the Mi-1 gene, silencing of Hsp90-1 occurs partially, as silenced plants showed a significant but not complete suppression of gene expression. Thus, our results demonstrate the requirement of Hsp90 in the Mi-1-mediated resistance to B. tabaci and reinforce the hypothesis of a common model for this resistance to nematodes and insects. Full article

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11 pages, 2755 KiB

Open AccessCommunication

Defoliation in Perennial Plants: Predictable and Surprising Results in Senna spp.

by Suzanne Koptur, Andrea Salas Primoli and María Cleopatra Pimienta

Plants 2023, 12(3), 587; https://doi.org/10.3390/plants12030587 - 29 Jan 2023

Cited by 1 | Viewed by 1172

Abstract

When some plants are defoliated, they may suffer by reaching a smaller final size than if they had not been damaged. Other plants may compensate for damage, ending up the same size as if they had not been damaged. Still, others may overcompensate, [...] Read more.

When some plants are defoliated, they may suffer by reaching a smaller final size than if they had not been damaged. Other plants may compensate for damage, ending up the same size as if they had not been damaged. Still, others may overcompensate, ending up larger after defoliation than if they had been spared from damage. We investigated the response of Senna species (Fabaceae) to defoliation, comparing two native and several ornamental congeners, all of which grow locally in southern Florida. Many Senna spp. bear foliar nectaries as nutritional resources for beneficial insects that may, in exchange, protect them from herbivores. We grew five species from seed and subjected them to three levels of defoliation for a period of several months to measure effects of leaf area removal on plant height, number of leaves, and number of extrafloral nectaries. Only three of five species displayed shorter plant heights with greater levels of damage. Two species produced fewer new leaves with moderate to severe defoliation. In only one species, the number of extrafloral nectaries decreased with defoliation, suggesting that while extrafloral nectar production may be an inducible defense in some species, producing more nectaries in response to damage does not occur in these Senna species. Full article

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17 pages, 2456 KiB

Open AccessArticle

Identification, Characterization, and Control of Black Spot on Chinese Kale Caused by Sphaerobolus cuprophilus sp. nov.

by Pancheewa Kalayanamitra, Kal Kalayanamitra, Sutasinee Nontajak, Paul W. J. Taylor, Nuchnart Jonglaekha and Boonsom Bussaban

Plants 2023, 12(3), 480; https://doi.org/10.3390/plants12030480 - 19 Jan 2023

Viewed by 2020

Abstract

Chinese kale (Brassica alboglabra) is commonly grown and consumed throughout Asia and is often treated with chemicals to control pests and diseases. In Thailand, public standards, Good Agricultural Practice (GAP), and International Federation of Organic Agriculture Movement (IFOAM) programs were introduced [...] Read more.

Chinese kale (Brassica alboglabra) is commonly grown and consumed throughout Asia and is often treated with chemicals to control pests and diseases. In Thailand, public standards, Good Agricultural Practice (GAP), and International Federation of Organic Agriculture Movement (IFOAM) programs were introduced for the cultivation of Chinese kale with minimum input of chemical treatments. Black spot caused by the fungus Sphaerobolus has been affecting the plants grown under IFOAM standards in Chiang Mai, Thailand, for several years. Strongly adhering glebal spore masses of the fungus on leaf and stem surfaces have adversely affected postharvest management, especially in the quality classification of the product. Both morphological and phylogenetic (combined ITS, mtSSU, and EF 1-α dataset) studies confirmed a novel species, S. cuprophilus. Pathogenicity tests involving inoculation of Chinese kale by non-wound and mulch inoculation bioassays resulted in the production of symptoms of black spot and the re-isolation of S. cuprophilus, indicating that the new fungal species is the causal agent of black spots. Inhibitory effects of antagonistic bacteria and chemical fungicides, both allowed for use in plant cultivation under either IFOAM or GAP standards, indicated that Bacillus amyloliquefaciens strains (PBT2 and YMB7), chlorothalonil (20 and 500 ppm) and thiophanate-methyl (500 and 1500 ppm) were the most effective in controlling the growth of the causal fungus by 83 to 93%. However, copper oxychloride (5 to 20 ppm), a recommended chemical in control of downy mildew of Chinese kale, showed hormetic effects on S. cuprophilus by promoting the growth and sporulation of the fungus. The findings of this study provide vital information regarding the association of S. cuprophilus and Chinese kale and will support decisions to manage fungal diseases of this vegetable. Full article

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17 pages, 3178 KiB

Open AccessArticle

Blackleg Yield Losses and Interactions with Verticillium Stripe in Canola (Brassica napus) in Canada

by Yixiao Wang, Stephen E. Strelkov and Sheau-Fang Hwang

Plants 2023, 12(3), 434; https://doi.org/10.3390/plants12030434 - 17 Jan 2023

Cited by 2 | Viewed by 1501

Abstract

Blackleg, caused by Leptosphaeria maculans, is an important disease of canola (Brassica napus). The pathogen can attack stems, leaves and pods, but basal stem cankers are most damaging and can result in significant yield losses. In Canada, Verticillium stripe ( [...] Read more.

Blackleg, caused by Leptosphaeria maculans, is an important disease of canola (Brassica napus). The pathogen can attack stems, leaves and pods, but basal stem cankers are most damaging and can result in significant yield losses. In Canada, Verticillium stripe (Verticillium longisporum) has recently emerged as another disease threat to canola. Symptoms of Verticillium stripe can resemble those of blackleg, and the two diseases may occur together. The effect of blackleg on yield was explored in field experiments with two canola hybrids and by evaluating a wider variety of hybrids in commercial crops in central Alberta, Canada. The impact on yield of L. maculans/V. longisporum interactions was also assessed under field and greenhouse conditions. In most hybrids, the relationship between blackleg severity and yield components was best explained by second-degree quadratic equations, although a linear relationship was found for one variety sampled in commercial fields. When L. maculans was co-inoculated with V. longisporum, blackleg severity and yield losses increased. In some cases, Verticillium stripe caused greater yield losses than blackleg. The results suggest that the interaction between L. maculans/V. longisporum may cause more severe losses in canola, highlighting the need for proactive disease management strategies. Full article

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20 pages, 4429 KiB

Open AccessArticle

Disease Forecasting for the Rational Management of Grapevine Mildews in the Chianti Bio-District (Tuscany)

by Giuliana Maddalena, Elena Marone Fassolo, Piero Attilio Bianco and Silvia Laura Toffolatti

Plants 2023, 12(2), 285; https://doi.org/10.3390/plants12020285 - 07 Jan 2023

Cited by 4 | Viewed by 1997

Abstract

Downy and powdery mildews are major grapevine diseases. In organic viticulture, a few fungicides with protectant activities (copper and sulphur in particular) can be used, and their preventative application frequently leads to unneeded spraying. The adoption of an epidemiological disease forecasting model could [...] Read more.

Downy and powdery mildews are major grapevine diseases. In organic viticulture, a few fungicides with protectant activities (copper and sulphur in particular) can be used, and their preventative application frequently leads to unneeded spraying. The adoption of an epidemiological disease forecasting model could optimise the timing of treatments and achieve a good level of disease protection. In this study, the effectiveness of the EPI (Etat Potentiel d’Infection) model in predicting infection risk for downy and powdery mildews was evaluated in nine organic vineyards located in Panzano in Chianti (FI), over a 2-year period (2020–2021). The reliability of the EPI model was investigated by comparing the disease intensities, the number of fungicide sprayings, the quantities of the fungicides (kg/ha), and the costs of the treatment achieved, with or without the use of the model, in a vineyard. The results obtained over two seasons indicated that, in most cases, the use of the EPI model accurately signalled the infection risk and allowed for a reduction in the frequency and cost of spraying, particularly for powdery mildew control (−40% sprayings, −20% costs compared to the farmer’s schedule), without compromising crop protection. The use of the EPI model can, therefore, contribute to more-sustainable disease management in organic viticulture. Full article

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15 pages, 1559 KiB

Open AccessArticle

Genetic Diversity and Geographic Distribution of Cucurbit-Infecting Begomoviruses in the Philippines

by Zhuan Yi Neoh, Hsuan-Chun Lai, Chung-Cheng Lin, Patcharaporn Suwor and Wen-Shi Tsai

Plants 2023, 12(2), 272; https://doi.org/10.3390/plants12020272 - 06 Jan 2023

Cited by 3 | Viewed by 2847

Abstract

Cucurbits are important economic crops worldwide. However, the cucurbit leaf curl disease (CuLCD), caused by whitefly-transmitted begomoviruses constrains their production. In Southeast Asia, three major begomoviruses, Tomato leaf curl New Delhi virus (ToLCNDV), Squash leaf curl China virus (SLCCNV) and Squash leaf curl [...] Read more.

Cucurbits are important economic crops worldwide. However, the cucurbit leaf curl disease (CuLCD), caused by whitefly-transmitted begomoviruses constrains their production. In Southeast Asia, three major begomoviruses, Tomato leaf curl New Delhi virus (ToLCNDV), Squash leaf curl China virus (SLCCNV) and Squash leaf curl Philippines virus (SLCuPV) are associated with CuLCD. SLCuPV and SLCCNV were identified in Luzon, the Philippines. Here, the genetic diversity and geographic distribution of CuLCD-associated begomoviruses in the Philippines were studied based on 103 begomovirus detected out of 249 cucurbit samples collected from 60 locations throughout the country in 2018 and 2019. The presence of SLCCNV and SLCuPV throughout the Philippines were confirmed by begomovirus PCR detection and viral DNA sequence analysis. SLCuPV was determined as a predominant CuLCD-associated begomovirus and grouped into two strains. Interestingly, SLCCNV was detected in pumpkin and bottle gourd without associated viral DNA-B and mixed-infected with SLCuPV. Furthermore, the pathogenicity of selected isolates of SLCCNV and SLCuPV was confirmed. The results provide virus genetic diversity associated with CuLCD for further disease management, especially in developing the disease-resistant cultivars in the Philippines as well as Southeast Asia. Full article

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21 pages, 3042 KiB

Open AccessArticle

Large–Scale Transposon Mutagenesis Reveals Type III Secretion Effector HopR1 Is a Major Virulence Factor in Pseudomonas syringae pv. actinidiae

by Takako Ishiga, Nanami Sakata, Giyu Usuki, Viet Tru Nguyen, Kenji Gomi and Yasuhiro Ishiga

Plants 2023, 12(1), 141; https://doi.org/10.3390/plants12010141 - 27 Dec 2022

Cited by 2 | Viewed by 2156

Abstract

Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) is a serious threat to kiwifruit production worldwide. Four biovars (Psa biovar 1; Psa1, Psa biovar 3; Psa3, Psa biovar 5; Psa5, and Psa biovar 6; Psa6) were reported in Japan, and [...] Read more.

Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) is a serious threat to kiwifruit production worldwide. Four biovars (Psa biovar 1; Psa1, Psa biovar 3; Psa3, Psa biovar 5; Psa5, and Psa biovar 6; Psa6) were reported in Japan, and virulent Psa3 strains spread rapidly to kiwifruit production areas worldwide. Therefore, there is an urgent need to develop critical management strategies for bacterial canker based on dissecting the dynamic interactions between Psa and kiwifruit. To investigate the molecular mechanism of Psa3 infection, we developed a rapid and reliable high-throughput flood-inoculation method using kiwifruit seedlings. Using this inoculation method, we screened 3000 Psa3 transposon insertion mutants and identified 91 reduced virulence mutants and characterized the transposon insertion sites in these mutants. We identified seven type III secretion system mutants, and four type III secretion effectors mutants including hopR1. Mature kiwifruit leaves spray-inoculated with the hopR1 mutant showed significantly reduced virulence compared to Psa3 wild-type, indicating that HopR1 has a critical role in Psa3 virulence. Deletion mutants of hopR1 in Psa1, Psa3, Psa5, and Psa6 revealed that the type III secretion effector HopR1 is a major virulence factor in these biovars. Moreover, hopR1 mutants of Psa3 failed to reopen stomata on kiwifruit leaves, suggesting that HopR1 facilitates Psa entry through stomata into plants. Furthermore, defense related genes were highly expressed in kiwifruit plants inoculated with hopR1 mutant compared to Psa wild-type, indicating that HopR1 suppresses defense-related genes of kiwifruit. These results suggest that HopR1 universally contributes to virulence in all Psa biovars by overcoming not only stomatal-based defense, but also apoplastic defense. Full article

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18 pages, 2776 KiB

Open AccessArticle

Pathogen Resistance Depending on Jacalin-Dirigent Chimeric Proteins Is Common among Poaceae but Absent in the Dicot Arabidopsis as Evidenced by Analysis of Homologous Single-Domain Proteins

by Lara Esch, Christian Kirsch, Lara Vogel, Jana Kelm, Nikolai Huwa, Maike Schmitz, Thomas Classen and Ulrich Schaffrath

Plants 2023, 12(1), 67; https://doi.org/10.3390/plants12010067 - 23 Dec 2022

Viewed by 1524

Abstract

MonocotJRLs are Poaceae-specific two-domain proteins that consist of a jacalin-related lectin (JRL) and a dirigent (DIR) domain which participate in multiple developmental processes, including disease resistance. For OsJAC1, a monocotJRL from rice, it has been confirmed that constitutive expression in transgenic rice [...] Read more.

MonocotJRLs are Poaceae-specific two-domain proteins that consist of a jacalin-related lectin (JRL) and a dirigent (DIR) domain which participate in multiple developmental processes, including disease resistance. For OsJAC1, a monocotJRL from rice, it has been confirmed that constitutive expression in transgenic rice or barley plants facilitates broad-spectrum disease resistance. In this process, both domains of OsJAC1 act cooperatively, as evidenced from experiments with artificially separated JRL- or DIR-domain-containing proteins. Interestingly, these chimeric proteins did not evolve in dicotyledonous plants. Instead, proteins with a single JRL domain, multiple JRL domains or JRL domains fused to domains other than DIR domains are present. In this study, we wanted to test if the cooperative function of JRL and DIR proteins leading to pathogen resistance was conserved in the dicotyledonous plant Arabidopsis thaliana. In Arabidopsis, we identified 50 JRL and 24 DIR proteins, respectively, from which seven single-domain JRL and two single-domain DIR candidates were selected. A single-cell transient gene expression assay in barley revealed that specific combinations of the Arabidopsis JRL and DIR candidates reduced the penetration success of barley powdery mildew. Strikingly, one of these pairs, AtJAX1 and AtDIR19, is encoded by genes located next to each other on chromosome one. However, when using natural variation and analyzing Arabidopsis ecotypes that express full-length or truncated versions of AtJAX1, the presence/absence of the full-length AtJAX1 protein could not be correlated with resistance to the powdery mildew fungus Golovinomyces orontii. Furthermore, an analysis of the additional JRL and DIR candidates in a bi-fluorescence complementation assay in Nicotiana benthamiana revealed no direct interaction of these JRL/DIR pairs. Since transgenic Arabidopsis plants expressing OsJAC1-GFP also did not show increased resistance to G. orontii, it was concluded that the resistance mediated by the synergistic activities of DIR and JRL proteins is specific for members of the Poaceae, at least regarding the resistance against powdery mildew. Arabidopsis lacks the essential components of the DIR-JRL-dependent resistance pathway. Full article

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17 pages, 5497 KiB

Open AccessArticle

Phenotypic and Genetic Variation in Morphophysiological Traits in Huanglongbing-Affected Mandarin Hybrid Populations

by Qibin Yu, Fanwei Dai, Riccardo Russo, Anirban Guha, Myrtho Pierre, Xiaokang Zhuo, Yuanzhi Zimmy Wang, Christopher Vincent and Frederick G. Gmitter, Jr.

Plants 2023, 12(1), 42; https://doi.org/10.3390/plants12010042 - 22 Dec 2022

Cited by 3 | Viewed by 1547

Abstract

Huanglongbing (HLB) caused by ‘Candidatus Liberibacter asiaticus’ (CLas) is the most costly disease for the global citrus industry. Currently, no effective tools have been found to control HLB. Most commercial citrus varieties are susceptible to HLB, though some citrus hybrid [...] Read more.

Huanglongbing (HLB) caused by ‘Candidatus Liberibacter asiaticus’ (CLas) is the most costly disease for the global citrus industry. Currently, no effective tools have been found to control HLB. Most commercial citrus varieties are susceptible to HLB, though some citrus hybrid cultivars have reduced sensitivity to the disease. Citrus breeding populations contain a large diversity of germplasm, with thousands of unique genotypes exhibiting a broad range of phenotypes. Understanding phenotypic variation and genetic inheritance in HLB-affected mandarin hybrid populations are crucial for breeding tolerant citrus varieties. In this study, we assessed 448 diverse mandarin hybrids coming from 30 crosses, and 45 additional accessions. For HLB tolerance, we measured HLB severity visual score and CLas titers by qPCR. We also measured seven morphophysiological traits indirectly related to HLB tolerance with leaf area index (LAI), leaf area (LA), leaf mass per area (LMA), photosystem II parameters (Fv/Fo, Fv/Fm), and photochemical performance index (PI_abs). By estimating the genetic variation in five half-sib families, we estimated the heritability of phenotypic traits and found a significant genetic effect on HLB visual score and photosynthesis parameters, which indicates opportunities for the genetic improvement of HLB tolerance. In addition, although it is easy to identify infected trees based on HLB symptomatic leaves, visually phenotyping whole trees can be difficult and inconsistent due to the interpersonal subjectivity of characterization. We investigated their relationships and found that LAI was highly correlated with HLB score, with correlation coefficients of r = 0.70 and r = 0.77 for the whole population and five half-sib families, respectively. Photochemical parameters showed significant correlation with HLB severity and responded differentially with the side of the canopy. Our study suggests that LAI and photochemical parameters could be used as a rapid and cost-effective method to evaluate HLB tolerance and inheritance in citrus breeding programs. Full article

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11 pages, 7294 KiB

Open AccessArticle

Genetic Variation in Common Bunt Resistance in Synthetic Hexaploid Wheat

by Amira M. I. Mourad, Alexey Morgounov, P. Stephen Baenziger and Samar M. Esmail

Plants 2023, 12(1), 2; https://doi.org/10.3390/plants12010002 - 20 Dec 2022

Cited by 3 | Viewed by 1504

Abstract

Common bunt (caused by Tilletia caries and T. Foetida) is a major wheat disease. It occurs frequently in the USA and Turkey and damages grain yield and quality. Seed treatment with fungicides is an effective method to control this disease. However, using [...] Read more.

Common bunt (caused by Tilletia caries and T. Foetida) is a major wheat disease. It occurs frequently in the USA and Turkey and damages grain yield and quality. Seed treatment with fungicides is an effective method to control this disease. However, using fungicides in organic and low-income fields is forbidden, and planting resistant cultivars are preferred. Due to the highly effective use of fungicides, little effort has been put into breeding resistant genotypes. In addition, the genetic diversity for this trait is low in modern wheat germplasm. Synthetic wheat genotypes were reported as an effective source to increase the diversity in wheat germplasm. Therefore, a set of 25 synthetics that are resistant to the Turkish common bunt race were evaluated against the Nebraska common bunt race. Four genotypes were found to be very resistant to Nebraska’s common bunt race. Using differential lines, four isolines carrying genes, Bt10, Bt11, Bt12, and Btp, were found to provide resistance against both Turkish and Nebraska common bunt races. Genotypes carrying any or all of these four genes could be used as a source of resistance in both countries. No correlation was found between common bunt resistance and some agronomic traits, which suggests that common bunt resistance is an independent trait. Full article

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17 pages, 3850 KiB

Open AccessArticle

Pure Camphor and a Thujone-Camphor Mixture as Eco-Friendly Antifeedants against Larvae and Adults of the Colorado Potato Beetle

by Jelica Lazarević, Igor Kostić, Darka Šešlija Jovanović, Dušica Ćalić, Slobodan Milanović and Miroslav Kostić

Plants 2022, 11(24), 3587; https://doi.org/10.3390/plants11243587 - 19 Dec 2022

Cited by 5 | Viewed by 1974

Abstract

The Colorado potato beetle (CPB) is a serious pest of economically important Solanaceae species. The use of essential oil compounds in pest management has been proposed as an alternative to harmful chemical insecticides that disturb human health and ecosystem functioning. We examined the [...] Read more.

The Colorado potato beetle (CPB) is a serious pest of economically important Solanaceae species. The use of essential oil compounds in pest management has been proposed as an alternative to harmful chemical insecticides that disturb human health and ecosystem functioning. We examined the antifeedant activity of three concentrations (0.125%, 0.25% and 0.5%) of pure camphor and a thujone-camphor mixture against 3rd instar larvae and adults. Their efficacy was evaluated according to the degree of leaf damage and avoidance of treated leaves by the CPB. Treatment of potato leaves significantly reduced leaf damage compared to the control. Leaf protection increased at higher concentrations of the examined compounds. Camphor was more effective against larvae and the thujone-camphor mixture was more effective against adults. Additionally, adults moved faster towards the control leaf disc in the two-choice olfactometer assay if an alternative disc was treated with a thujone-camphor mixture, whereas larvae responded similarly to the two potential repellents. However, after contact with the leaf disc treated with the highest compound concentration, the larvae escaped faster from the thujone-camphor mixture than from pure camphor. In conclusion, both examined compounds are promising eco-friendly antifeedants, but their efficacy depends on the developmental stage of the beetle, compound type and applied concentration. Full article

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9 pages, 4534 KiB

Open AccessArticle

Effect of Rhizome Fragment Length and Burial Depth on the Emergence of a Tropical Invasive Weed Cyperus aromaticus (Navua Sedge)

by Aakansha Chadha, Singarayer K. Florentine, Kunjithapatham Dhileepan and Christopher Turville

Plants 2022, 11(23), 3331; https://doi.org/10.3390/plants11233331 - 01 Dec 2022

Cited by 1 | Viewed by 1433

Abstract

Cyperus aromaticus (Navua sedge) is a problematic perennial weed in pastures and crops including sugarcane, banana, rice, and fruits and vegetables in tropical climates. It reproduces both via rhizomes and seeds. As a regenerative and storage organ, these rhizomes play an important part [...] Read more.

Cyperus aromaticus (Navua sedge) is a problematic perennial weed in pastures and crops including sugarcane, banana, rice, and fruits and vegetables in tropical climates. It reproduces both via rhizomes and seeds. As a regenerative and storage organ, these rhizomes play an important part in the invasion, establishment, and persistence of this weed. To eliminate their regenerative ability, it is important to understand the regrowth potential with respect to rhizome fragment size and burial depth. This study evaluated the emergence of C. aromaticus from rhizomes in a controlled condition. Three different sizes of rhizome fragments were buried at seven depths of up to 20 cm in two soil types. The experimental measurements included (i) the time for tillers to emerge, (ii) the cumulative emergence of tillers, recorded weekly, and (iii) the number of underground emerging tillers. The cumulative shoot emergence and the number of underground tillers produced were found to be positively correlated with the initial length of the rhizome fragments and negatively correlated with the burial depth. The time for the emergence of the tillers was negatively correlated with the burial depth, and soil type had no significant effect on any of the parameters recorded. There was no emergence recorded from rhizomes buried at 15 cm depth and deeper, irrespective of their size. Our results indicate that the combination of the fragmentation of rhizomes into small pieces and a deep burial, below 15 cm, is an important aspect to control the regeneration of C. aromaticus from rhizomes, if tillage is carried out, and can therefore form a part of an integrated weed management strategy for this troublesome weed. Full article

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10 pages, 1844 KiB

Open AccessArticle

Quantitative Real-Time PCR Based on SYBR Green Technology for the Identification of Philaenus italosignus Drosopoulos & Remane (Hemiptera Aphrophoridae)

by Domenico Rizzo, Matteo Bracalini, Sara Campigli, Anita Nencioni, Francesco Porcelli, Guido Marchi, Daniele Da Lio, Linda Bartolini, Elisabetta Rossi, Patrizia Sacchetti and Tiziana Panzavolta

Plants 2022, 11(23), 3314; https://doi.org/10.3390/plants11233314 - 30 Nov 2022

Viewed by 1213

Abstract

The use of molecular tools to identify insect pests is a critical issue, especially when rapid and reliable tests are required. We proposed a protocol based on qPCR with SYBR Green technology to identify Philaenus italosignus (Hemiptera, Aphrophoridae). The species is one of [...] Read more.

The use of molecular tools to identify insect pests is a critical issue, especially when rapid and reliable tests are required. We proposed a protocol based on qPCR with SYBR Green technology to identify Philaenus italosignus (Hemiptera, Aphrophoridae). The species is one of the three spittlebugs able to transmit Xylella fastidiosa subsp. pauca ST53 in Italy, together with Philaenus spumarius and Neophilaenus campestris. Although less common than the other two species, its identification is key to verifying which role it can play when locally abundant. The proposed assay shows analytical specificity being inclusive with different populations of the target species and exclusive with non-target taxa, either taxonomically related or not. Moreover, it shows analytical sensibility, repeatability, and reproducibility, resulting in an excellent candidate for an official diagnostic method. The molecular test can discriminate P. italosignus from all non-target species, including the congeneric P. spumarius. Full article

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15 pages, 1047 KiB

Open AccessArticle

Western Spruce Budworm Effects on Forest Resilience

by Adam D. Polinko, Marguerite A. Rapp, Andrew J. Sánchez Meador, Andrew D. Graves, Daniel E. Ryerson and Kristen M. Waring

Plants 2022, 11(23), 3266; https://doi.org/10.3390/plants11233266 - 28 Nov 2022

Viewed by 1145

Abstract

Western spruce budworm (Choristoneura freemani Razowski) is the most destructive defoliator of forests in the western US. Forests in northern New Mexico experienced high levels of WSBW-caused defoliation and subsequent mortality between the 1980s and 2010s. The effects of severe western spruce [...] Read more.

Western spruce budworm (Choristoneura freemani Razowski) is the most destructive defoliator of forests in the western US. Forests in northern New Mexico experienced high levels of WSBW-caused defoliation and subsequent mortality between the 1980s and 2010s. The effects of severe western spruce budworm outbreaks on stand dynamics in the US Southwest are still relatively unknown, but understanding the impacts is important to the management and resilience of these forests. To begin addressing this knowledge gap, we conducted a study along two gradients: an elevational gradient from mixed-conifer to spruce-fir forests and a gradient of WSBW-caused defoliation intensity. We recorded overstory and understory stand conditions (size structure, species composition, damaging agents). Western spruce budworm was the primary damaging agent of host trees in all stands andcaused host tree mortality across all size classes, particularly in spruce-fir stands. Results indicate an unsustainable level of mortality in spruce-fir stands and a transition towards non-host species in mixed-conifer stands. Low levels of regeneration coupled with high overstory mortality rates indicate a potential lack of resilience in spruce-fir stands, whereas resilience to future western spruce budworm defoliation events may have increased in mixed-conifer stands affected by these outbreaks. Full article

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14 pages, 2900 KiB

Open AccessTechnical Note

Use of a RT-qPCR Method to Estimate Mycorrhization Intensity and Symbiosis Vitality in Grapevine Plants Inoculated with Rhizophagus irregularis

by Morgane Duret, Xi Zhan, Lorène Belval, Christine Le Jeune, Réjane Hussenet, Hélène Laloue, Christophe Bertsch, Julie Chong, Laurence Deglène-Benbrahim and Laure Valat

Plants 2022, 11(23), 3237; https://doi.org/10.3390/plants11233237 - 25 Nov 2022

Cited by 3 | Viewed by 1554

Abstract

Assessing the mycorrhization level in plant roots is essential to study the effect of arbuscular mycorrhizal fungi (AMF) on plant physiological responses. Common methods used to quantify the mycorrhization of roots are based on microscopic visualization of stained fungal structures within the cortical [...] Read more.

Assessing the mycorrhization level in plant roots is essential to study the effect of arbuscular mycorrhizal fungi (AMF) on plant physiological responses. Common methods used to quantify the mycorrhization of roots are based on microscopic visualization of stained fungal structures within the cortical cells. While this method is readily accessible, it remains time-consuming and does not allow checking of the symbiosis vitality. The aim of this work is thus to develop an efficient method for assessing the intensity and vitality of mycorrhiza associated with grapevine through gene expression analyses by RT-qPCR. To this end, grapevine plants were inoculated with the AMF Rhizophagus irregularis (Ri). The relationship between mycorrhization level, assessed by microscopy, and expression of several fungus and grapevine genes involved in the symbiosis was investigated. In AMF-inoculated plants, transcript amounts of fungal constitutively-expressed genes Ri18S, RiTEF1α and RiαTub were significantly correlated to mycorrhization intensity, particularly Ri18S. Grapevine (VvPht1.1 and VvPht1.2) and AMF (GintPT, Ri14-3-3 and RiCRN1) genes, known to be specifically expressed during the mycorrhizal process, were significantly correlated to arbuscular level in the whole root system determined by microscopy. The best correlations were obtained with GintPT on the fungal side and VvPht1.2 on the plant side. Despite some minor discrepancies between microscopic and molecular techniques, the monitoring of Ri18S, GintPT and VvPht1.2 gene expression could be a rapid, robust and reliable method to evaluate the level of mycorrhization and to assess the vitality of AMF. It appears particularly useful to identify AMF-inoculated plants with very low colonization level, or with non-active fungal structures. Moreover, it can be implemented simultaneously with the expression analysis of other genes of interest, saving time compared to microscopic analyses. Full article

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12 pages, 1155 KiB

Open AccessArticle

Forest–Fruticulture Conversion Alters Soil Traits and Soil Organic Matter Compartments

by Bruna Firmino Enck, Milton Cesar Costa Campos, Marcos Gervásio Pereira, Fernando Gomes de Souza, Otavio Augusto Queiroz Santos, Yan Vidal de Figueiredo Gomes Diniz, Thalita Silva Martins, José Mauricio Cunha, Alan Ferreira Leite de Lima and Tancredo Augusto Feitosa de Souza

Plants 2022, 11(21), 2917; https://doi.org/10.3390/plants11212917 - 29 Oct 2022

Cited by 7 | Viewed by 1586

Abstract

Fruticulture in the Amazonian Rainforest is one of the main causes of deforestation, biodiversity loss, and soil erosion. Fruticulture plays a key role in the soil traits and soil organic matter (SOM) compartments by altering the soil ecosystem. Our aim was to assess [...] Read more.

Fruticulture in the Amazonian Rainforest is one of the main causes of deforestation, biodiversity loss, and soil erosion. Fruticulture plays a key role in the soil traits and soil organic matter (SOM) compartments by altering the soil ecosystem. Our aim was to assess the influence of Forest–Fruticulture conversion on soil traits, and SOM fractions in Brazil’s Legal Amazon. The experiment was carried out in field conditions using four land uses as main treatments: Bixa orellana, Theobroma grandiflorum, Paullinia cupana, and the Amazon Rainforest. The soil physicochemical traits were analyzed using samples that were collected from 0–5, 5–10, and 10–20 cm soil depth by using grids (10 × 10 m) with 36 sampling points. Our results showed that the Fruticulture promoted an increase in bulk density, GMD, aggregate diameter, soil porosity, gravimetric moisture, sand, clay, carbon associated with humic acid, and, the sum of bases (K⁺, Ca²⁺, and Mg²⁺), while the Amazon Rainforest showed the highest values of silt, soil P content, SOC, p-SOC, m-SOC, carbon associated with fulvic acid, humine, and soil C stock. Overall, the fruticulture farming systems have negative effects on SOM compartments. The results of our study highlight the importance of considering fruticulture with endemic plant species by promoting soil fertility and soil aggregation. Full article

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21 pages, 1333 KiB

Open AccessArticle

Foliar Diseases and the Associated Fungi in Rice Cultivated in Kenya

by Everlyne M. Nganga, Martina Kyallo, Philemon Orwa, Felix Rotich, Emily Gichuhi, John M. Kimani, David Mwongera, Bernice Waweru, Phoebe Sikuku, David M. Musyimi, Samuel K. Mutiga, Cathrine Ziyomo, Rosemary Murori, Lusike Wasilwa, James C. Correll and Nicholas J. Talbot

Plants 2022, 11(9), 1264; https://doi.org/10.3390/plants11091264 - 07 May 2022

Cited by 3 | Viewed by 3059

Abstract

We conducted a survey to assess the occurrence and severity of rice blast and brown spot diseases on popular cultivars grown in the Busia, Kirinyaga, and Kisumu counties of Kenya in 2019. Working with agricultural extension workers within rice production areas, we interviewed [...] Read more.

We conducted a survey to assess the occurrence and severity of rice blast and brown spot diseases on popular cultivars grown in the Busia, Kirinyaga, and Kisumu counties of Kenya in 2019. Working with agricultural extension workers within rice production areas, we interviewed farmers (n = 89) regarding their preferred cultivars and their awareness of blast disease, as this was the major focus of our research. We scored the symptoms of blast and brown spot and assessed the lodging, plant height, and maturity of the crops (days after planting). Furthermore, we collected leaf and neck tissues for the assessment of the prevailing fungal populations. We used specific DNA primers to screen for the prevalence of the causal pathogens of blast, Magnaporthe oryzae, and brown spot, Cochliobolus miyabeanus, on asymptomatic and symptomatic leaf samples. We also conducted fungal isolations and PCR-sequencing to identify the fungal species in these tissues. Busia and Kisumu had a higher diversity of cultivars compared to Kirinyaga. The aromatic Pishori (NIBAM 11) was preferred and widely grown for commercial purposes in Kirinyaga, where 86% of Kenyan rice is produced. NIBAM108 (IR2793-80-1) and BW196 (NIBAM 109) were moderately resistant to blast, while NIBAM110 (ITA310) and Vietnam were susceptible. All the cultivars were susceptible to brown spot except for KEH10005 (Arize Tej Gold), a commercial hybrid cultivar. We also identified diverse pathogenic and non-pathogenic fungi, with a high incidence of Nigrospora oryzae, in the rice fields of Kirinyaga. There was a marginal correlation between disease severity/incidence and the occurrence of causal pathogens. This study provides evidence of the need to strengthen pathogen surveillance through retraining agricultural extension agents and to breed for blast and brown spot resistance in popular rice cultivars in Kenya. Full article

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27 pages, 3441 KiB

Open AccessArticle

Mixtures of Macro and Micronutrients Control Grape Powdery Mildew and Alter Berry Metabolites

by Lior Gur, Yigal Cohen, Omer Frenkel, Ron Schweitzer, Meir Shlisel and Moshe Reuveni

Plants 2022, 11(7), 978; https://doi.org/10.3390/plants11070978 - 04 Apr 2022

Cited by 6 | Viewed by 2789

Abstract

Powdery mildew caused by the fungus Erysiphe necator is a major grape disease worldwide. It attacks foliage and berries and reduces yield and wine quality. Fungicides are mainly used for combating the disease. Fungicide resistance and the global requisite to reduce pesticide deployment [...] Read more.

Powdery mildew caused by the fungus Erysiphe necator is a major grape disease worldwide. It attacks foliage and berries and reduces yield and wine quality. Fungicides are mainly used for combating the disease. Fungicide resistance and the global requisite to reduce pesticide deployment encourage the use of environment-friendly alternatives for disease management. Our field experiments showed that the foliar application of the potassium phosphate fertilizer Top-KP+ (1-50-33 NPK) reduced disease incidence on leaves and clusters by 15–65% and severity by 75–90%, compared to untreated vines. Top-KP+ mixed with Nanovatz (containing the micronutrients boron (B) and zinc (Zn)) or with TruPhos Platinum (a mixture containing N, P₂O₅, K₂O, Zn, B, Mg, Fe, Mn, Cu, Mo, and CO) further reduced disease incidence by 30–90% and disease severity by 85–95%. These fertilizers were as effective as the fungicide tebuconazole. Tank mixtures of fertilizers and tebuconazole further enhanced control efficacy in the vineyards. The modes of action of fertilizers in disease control were elucidated via tests with grape seedlings, microscopy, and berry metabolomics. Fertilizers applied preventively to the foliage of grape seedlings inhibited powdery mildew development. Application onto existing mildew colonies plasmolyzed mycelia and conidia and arrested the development of the disease. Berries treated with fertilizers or with a fungicide showed a significant increase in anti-fungal and antioxidant metabolites. Twenty-two metabolites, including non-protein amino acids and carbohydrates, known for their anti-fungal and bioactive effects, were significantly upregulated in grapes treated with fertilizers as compared to grapes treated with a fungicide, suggesting possible indirect activity against the pathogen. Esters and organic acids that contribute to wine quality were also upregulated. We conclude that integrating macro and micronutrients in spray programs in commercial vineyards shall control powdery mildew, reduce fungicide deployment, delay the buildup of fungicide resistance, and may improve wine quality. Full article

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13 pages, 1862 KiB

Open AccessArticle

Evaluation of Pseudomonas fulva PS9.1 and Bacillus velezensis NWUMFkBS10.5 as Candidate Plant Growth Promoters during Maize-Fusarium Interaction

by Adetomiwa A. Adeniji and Olubukola O. Babalola

Plants 2022, 11(3), 324; https://doi.org/10.3390/plants11030324 - 26 Jan 2022

Cited by 6 | Viewed by 2968

Abstract

Based on in vitro assessments, molecular and chemical analysis, Pseudomonas fulva PS9.1 and Bacillus velezensis NWUMFkBS10.5 are candidate biocontrol agents for plant disease management including maize fusariosis, a disease caused by members of the Fusarium species. This in vivo study evaluated the bio-protective [...] Read more.

Based on in vitro assessments, molecular and chemical analysis, Pseudomonas fulva PS9.1 and Bacillus velezensis NWUMFkBS10.5 are candidate biocontrol agents for plant disease management including maize fusariosis, a disease caused by members of the Fusarium species. This in vivo study evaluated the bio-protective potential of the aforementioned rhizobacteria strains on maize against the proliferation of the pathogenic fungus Fusarium graminearum (Fg). The study results show that the bacterized plants were not susceptible to Fg aggression and the antagonists displayed the capability to proliferate in the presence of other likely competing microflora. The screen-house data also suggest that the presence of resident soil microbiota impacted the activity of antagonists (PS9.1 and NWUMFkBS10.5). This variation was recorded in the soil treatments (sterilized and unsterilized soil). In all the experimental periods, bacterized maize plants with or without Fg inoculation significantly (p = 0.05) grew better in unsterilized soil. Besides, during the experimental periods, all the consortia treatments with or without Fg infection regardless of the soil used demonstrated appreciable performance. The result of this study suggests that the microbial agents can actively colonize the surface of their maize plant host, improve plant growth, and suppress the growth of phytopathogens. Considering their overall performance in this screen-house evaluation, P. fulva PS9.1 and B. velezensis NWUMFkBS10.5 have potential for field applications. All safety issues regarding their use under field conditions and risks associated with their extended-release into the environmental will, however, be assessed prior to further bioformulation, field investigation, and scale-up. Full article

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2021

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19 pages, 3137 KiB

Open AccessArticle

Defence Responses Associated with Elicitor-Induced, Cultivar-Associated Resistance to Latania Scale in Kiwifruit

by Kirstin Wurms, Annette Ah Chee, Kate Stannard, Rachelle Anderson, Dwayne Jensen, Janine Cooney and Duncan Hedderley

Plants 2022, 11(1), 10; https://doi.org/10.3390/plants11010010 - 21 Dec 2021

Cited by 5 | Viewed by 2721

Abstract

Latania scale insect is a pest of global significance affecting kiwifruit. The sessile insect (life stage: settled crawler—mature adult) is covered with a waxy cap that protects it from topical pesticides, so increasingly, a selection of resistant cultivars and application of elicitors are [...] Read more.

Latania scale insect is a pest of global significance affecting kiwifruit. The sessile insect (life stage: settled crawler—mature adult) is covered with a waxy cap that protects it from topical pesticides, so increasingly, a selection of resistant cultivars and application of elicitors are being used in pest control. Thus far, the application of a salicylic acid (SA) phytohormone pathway elicitor, acibenzolar-S-methyl (ASM), has been shown to reduce insect development (as indicated by cap size) on one kiwifruit cultivar (‘Hayward’). To investigate how cultivar-associated resistance is affected by the ability to respond to different elicitors, we measured phytohormones (by LCMS) and gene expression (by qPCR and NanoString) on latania scale-tolerant ‘Hort16A’ and susceptible ‘Hayward’ kiwifruit over two seasons. Potted plants in the presence/absence of settled latania scales were treated with ASM (0.2 g/L) or methyl jasmonate (MeJA, 0.05% v/v), representing elicitors of the SA and JA signalling pathways, respectively. ‘Hort16A’ cultivar resistance to latania scale was associated with elevated expression of SA and SA-related defence genes (PR1 and two PR2 family genes) in the ASM treatment. MeJA treatments did not significantly affect insect development in ‘Hayward’ (latania scale did not survive on ‘Hort16A’) and did not correlate with phytohormone and gene expression measurements in either cultivar. ‘Hayward’ had greater concentrations than ‘Hort16A’ of inert storage forms of both SA and JA across all treatments. This information contributes to the selection of tolerant cultivars and the effective use of elicitors for control of latania scale in kiwifruit. Full article

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14 pages, 3321 KiB

Open AccessArticle

Arbuscular Mycorrhizal Fungi from Argentinean Highland Puna Soils Unveiled by Propagule Multiplication

by Fernanda Covacevich, Keren Hernández Guijarro, Esteban M. Crespo, Erica Lumini, María Soledad Rivero Mega and Mónica A. Lugo

Plants 2021, 10(9), 1803; https://doi.org/10.3390/plants10091803 - 30 Aug 2021

Cited by 9 | Viewed by 2908

Abstract

Low arbuscular-mycorrhizal (AM) sporulation in arid field soils limits our knowledge of indigenous species when diversity studies are based only on spore morphology. Our aim was to use different approaches (i.e., spore morphological approach and PCR–SSCP (single-strand-conformation-polymorphism) analysis after trap plant multiplication strategies [...] Read more.

Low arbuscular-mycorrhizal (AM) sporulation in arid field soils limits our knowledge of indigenous species when diversity studies are based only on spore morphology. Our aim was to use different approaches (i.e., spore morphological approach and PCR–SSCP (single-strand-conformation-polymorphism) analysis after trap plant multiplication strategies to improve the knowledge of the current richness of glomalean AM fungi (Glomerales; Glomeromycota) from the Argentine Puna. Indigenous propagules from two pristine sites at 3870 and 3370 m of elevation were multiplied using different host plants; propagation periods (2–6 months), and subculture cycles (1; 2; or 3) from 5 to 13 months. The propagule multiplication experiment allowed the detection of different glomoid taxa of Funneliformis spp. and Rhizoglomus spp., which were considered cryptic species since they had never been found in Puna soils before. On the other hand; almost all the generalist species previously described were recovered from cultures; except for Glomus ambisporum. Both plant host selection and culture times are critical for Glomerales multiplication. The SSCP analysis complemented the morphological approach and showed a high variability of Glomus at each site; revealing the presence of Funneliformis mosseae. This study demonstrates that AMF trap culture (TC) is a useful strategy for improving the analysis of AM fungal diversity/richness in the Argentinean highlands. Full article

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16 pages, 1023 KiB

Open AccessArticle

Assessment of the Hyperspectral Data Analysis as a Tool to Diagnose Xylella fastidiosa in the Asymptomatic Leaves of Olive Plants

by Carmela Riefolo, Ilaria Antelmi, Annamaria Castrignanò, Sergio Ruggieri, Ciro Galeone, Antonella Belmonte, Maria Rita Muolo, Nicola A. Ranieri, Rossella Labarile, Giovanni Gadaleta and Franco Nigro

Plants 2021, 10(4), 683; https://doi.org/10.3390/plants10040683 - 01 Apr 2021

Cited by 10 | Viewed by 2521

Abstract

Xylella fastidiosa is a bacterial pathogen affecting many plant species worldwide. Recently, the subspecies pauca (Xfp) has been reported as the causal agent of a devastating disease on olive trees in the Salento area (Apulia region, southeastern Italy), where centenarian and [...] Read more.

Xylella fastidiosa is a bacterial pathogen affecting many plant species worldwide. Recently, the subspecies pauca (Xfp) has been reported as the causal agent of a devastating disease on olive trees in the Salento area (Apulia region, southeastern Italy), where centenarian and millenarian plants constitute a great agronomic, economic, and landscape trait, as well as an important cultural heritage. It is, therefore, important to develop diagnostic tools able to detect the disease early, even when infected plants are still asymptomatic, to reduce the infection risk for the surrounding plants. The reference analysis is the quantitative real time-Polymerase-Chain-Reaction (qPCR) of the bacterial DNA. The aim of this work was to assess whether the analysis of hyperspectral data, using different statistical methods, was able to select with sufficient accuracy, which plants to analyze with PCR, to save time and economic resources. The study area was selected in the Municipality of Oria (Brindisi). Partial Least Square Regression (PLSR) and Canonical Discriminant Analysis (CDA) indicated that the most important bands were those related to the chlorophyll function, water, lignin content, as can also be seen from the wilting symptoms in Xfp-infected plants. The confusion matrix of CDA showed an overall accuracy of 0.67, but with a better capability to discriminate the infected plants. Finally, an unsupervised classification, using only spectral data, was able to discriminate the infected plants at a very early stage of infection. Then, in phase of testing qPCR should be performed only on the plants predicted as infected from hyperspectral data, thus, saving time and financial resources. Full article

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13 pages, 998 KiB

Open AccessReview

Pomegranate Peel Extracts as Safe Natural Treatments to Control Plant Diseases and Increase the Shelf-Life and Safety of Fresh Fruits and Vegetables

by Imen Belgacem, Maria G. Li Destri Nicosia, Sonia Pangallo, Ahmed Abdelfattah, Massimo Benuzzi, Giovanni E. Agosteo and Leonardo Schena

Plants 2021, 10(3), 453; https://doi.org/10.3390/plants10030453 - 27 Feb 2021

Cited by 25 | Viewed by 5576

Abstract

Although the Green Revolution was a milestone in agriculture, it was accompanied by intensive use of synthetic pesticides, which has raised serious concerns due to their impact on human and environmental health. This is increasingly stimulating the search for safer and more eco-friendly [...] Read more.

Although the Green Revolution was a milestone in agriculture, it was accompanied by intensive use of synthetic pesticides, which has raised serious concerns due to their impact on human and environmental health. This is increasingly stimulating the search for safer and more eco-friendly alternative means to control plant diseases and prevent food spoilage. Among the proposed alternatives, pomegranate peel extracts (PPEs) are very promising because of their high efficacy. In the present review, we discuss the complex mechanisms of action that include direct antimicrobial activity and induction of resistance in treated plant tissues and highlight the importance of PPE composition in determining their activity. The broad spectrum of activity, wide range of application and high efficiency of PPEs against bacterial, fungal and viral plant pathogens suggest a potential market not only restricted to organic production but also integrated farming systems. Considering that PPEs are non-chemical by-products of the pomegranate industry, they are perceived as safe by the public and may be integrated in circular economy strategies. This will likely encourage agro-pharmaceutical industries to develop commercial formulations and speed up the costly process of registration. Full article

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11 pages, 1093 KiB

Open AccessArticle

Creation and Validation of a Temperature-Based Phenology Model for Meloidogyne incognita on Common Bean

by Ariadna Giné, Patricia Monfort and Francisco Javier Sorribas

Plants 2021, 10(2), 240; https://doi.org/10.3390/plants10020240 - 26 Jan 2021

Cited by 5 | Viewed by 1837

Abstract

The thermal requirements of Meloidogyne incognita on Phaseolus vulgaris in a set of constant soil temperatures were determined and the phenology model was validated at fluctuating soil temperatures. The base temperature (Tb) and the thermal constant (S) from nematode [...] Read more.

The thermal requirements of Meloidogyne incognita on Phaseolus vulgaris in a set of constant soil temperatures were determined and the phenology model was validated at fluctuating soil temperatures. The base temperature (Tb) and the thermal constant (S) from nematode inoculation to females starting to lay eggs were 11.3 °C and 323 accumulated degree days (DD), respectively; Tb = 10.5 °C and S = 147 DD from egg production to emergence of juveniles; and Tb = 11.1 °C and S = 476 DD for life cycle completion. At fluctuating soil temperatures in pots with the minimum lower than Tb and the maximum higher than To (optimal temperature), the DD calculation was carried out by the average daily temperature–Tb (ADTb) and the single sine method over Tb (SSTb) with horizontal, intermediate, and vertical cutoffs. The most accurate were the ADTb and the SSTb with horizontal and intermediate cutoffs (93–106% of the predicted value) but the vertical underestimated the accumulated DD (75–82% of the predicted value). When fluctuating soil temperatures were between Tb and To in a plastic greenhouse, only the ADTb method was used. Life cycle completion was observed around 465 DD (accuracy between 0.95 and 0.99) at four different transplanting dates. Full article

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18 pages, 5361 KiB

Open AccessArticle

Large-Scale Seedling Grow-Out Experiments Do Not Support Seed Transmission of Sweet Potato Leaf Curl Virus in Sweet Potato

by Sharon A. Andreason, Omotola G. Olaniyi, Andrea C. Gilliard, Phillip A. Wadl, Livy H. Williams, D. Michael Jackson, Alvin M. Simmons and Kai-Shu Ling

Plants 2021, 10(1), 139; https://doi.org/10.3390/plants10010139 - 12 Jan 2021

Cited by 8 | Viewed by 2668

Abstract

Sweet potato leaf curl virus (SPLCV) threatens global sweet potato production. SPLCV is transmitted by Bemisia tabaci or via infected vegetative planting materials; however, SPLCV was suggested to be seed transmissible, which is a characteristic that is disputed for geminiviruses. The objective of [...] Read more.

Sweet potato leaf curl virus (SPLCV) threatens global sweet potato production. SPLCV is transmitted by Bemisia tabaci or via infected vegetative planting materials; however, SPLCV was suggested to be seed transmissible, which is a characteristic that is disputed for geminiviruses. The objective of this study was to revisit the validity of seed transmission of SPLCV in sweet potato. Using large-scale grow-out of sweet potato seedlings from SPLCV-contaminated seeds over 4 consecutive years, approximately 23,034 sweet potato seedlings of 118 genotype entries were evaluated. All seedlings germinating in a greenhouse under insect-proof conditions or in a growth chamber were free of SPLCV; however, a few seedlings grown in an open bench greenhouse lacking insect exclusion tested positive for SPLCV. Inspection of these seedlings revealed that B. tabaci had infiltrated the greenhouse. Therefore, transmission experiments were conducted using B. tabaci MEAM1, demonstrating successful vector transmission of SPLCV to sweet potato. Additionally, tests on contaminated seed coats and germinating cotyledons demonstrated that SPLCV contaminated a high percentage of seed coats collected from infected maternal plants, but SPLCV was never detected in emerging cotyledons. Based on the results of grow-out experiments, seed coat and cotyledon tests, and vector transmission experiments, we conclude that SPLCV is not seed transmitted in sweet potato. Full article

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2020

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13 pages, 895 KiB

Open AccessArticle

Use of LAMP for Assessing Botrytis cinerea Colonization of Bunch Trash and Latent Infection of Berries in Grapevines

by Melissa Si Ammour, Eleonora Castaldo, Giorgia Fedele and Vittorio Rossi

Plants 2020, 9(11), 1538; https://doi.org/10.3390/plants9111538 - 11 Nov 2020

Cited by 5 | Viewed by 2219

Abstract

A real-time loop-mediated isothermal amplification (LAMP) assay was evaluated for the detection of Botrytis cinerea in grapevine bunch trash, immature berries, and ripening berries. A simple method for the preparation of crude extracts of grape tissue was also developed for on-site LAMP analysis. [...] Read more.

A real-time loop-mediated isothermal amplification (LAMP) assay was evaluated for the detection of Botrytis cinerea in grapevine bunch trash, immature berries, and ripening berries. A simple method for the preparation of crude extracts of grape tissue was also developed for on-site LAMP analysis. When tested with 14 other fungal species frequently found in grapevines, the LAMP assay was specific and sensitive to a B. cinerea DNA quantity of 0.1 ng/µL. The sensitivity was further tested using bunch trash samples with B. cinerea colonization levels between 6 and 100% and with bulk-berry samples composed of 4 pathogen-free berries or 4 berries among which 25 to 100% had been inoculated with B. cinerea. The LAMP assay detected the lowest B. cinerea colonization level tested in bunch trash and in immature and mature berries in less than 20 min. In single-berry experiments, LAMP amplified B. cinerea DNA from all artificially inoculated individual immature and mature berries. No amplification occurred in B. cinerea-free material. The real-time LAMP assay has the potential to be used as a rapid on-site diagnostic tool for assessing B. cinerea colonization in bunch trash and B. cinerea latent infections in berries, which represent critical stages for decision-making about disease management. Full article

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16 pages, 1546 KiB

Open AccessArticle

Novel Bioformulations Developed from Pseudomonas putida BSP9 and Its Biosurfactant for Growth Promotion of Brassica juncea (L.)

by Isha Mishra, Tahmish Fatima, Dilfuza Egamberdieva and Naveen Kumar Arora

Plants 2020, 9(10), 1349; https://doi.org/10.3390/plants9101349 - 12 Oct 2020

Cited by 16 | Viewed by 4091

Abstract

In this study, Pseudomonas putida BSP9 isolated from rhizosphere of Brassica juncea was investigated for its plant growth promoting and biosurfactant producing activities. The isolate showed the ability to produce indole acetic acid, siderophore, phosphate solubilization activity and was an efficient producer of [...] Read more.

In this study, Pseudomonas putida BSP9 isolated from rhizosphere of Brassica juncea was investigated for its plant growth promoting and biosurfactant producing activities. The isolate showed the ability to produce indole acetic acid, siderophore, phosphate solubilization activity and was an efficient producer of biosurfactant. Purification (of the biosurfactant) by thin layer chromatography (TLC) and further characterization by Fourier transform infrared spectroscopy (FTIR) revealed that biosurfactant produced by the isolate belonged to the glycolipid category, which is largely produced by Pseudomonas sp. In addition, liquid chromatography-mass spectroscopy (LC-MS) analysis showed the presence of a mixture of six mono-rhamnolipidic and a di-rhamnolipidic congeners, confirming it as a rhamnolipid biosurfactant. Bioformulations were developed using BSP9 and its biosurfactant to check their impact on promoting plant growth in B. juncea. It was noted from the study that bioformulations amended with biosurfactant (singly or in combination with BSP9) resulted in enhancement in the growth parameters of B. juncea as compared to untreated control. Maximum increment was achieved by plants inoculated with bioformulation that had BSP9 plus biosurfactant. The study also suggested that growth promotion was significant up to a threshold level of biosurfactant and that further increasing the concentration did not further enhance the growth parameter values of the plant. The study proves that novel bioformulations can be developed by integrating plant growth promoting rhizobacteria (PGPR) and their biosurfactant, and they can be effectively used for increasing agricultural productivity while minimizing our dependence on agrochemicals. Full article

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18 pages, 6286 KiB

Open AccessEditor’s ChoiceArticle

Genetic Diversity of Fusarium oxysporum f. sp. cubense, the Fusarium Wilt Pathogen of Banana, in Ecuador

by Freddy Magdama, Lorena Monserrate-Maggi, Lizette Serrano, José García Onofre and María del Mar Jiménez-Gasco

Plants 2020, 9(9), 1133; https://doi.org/10.3390/plants9091133 - 01 Sep 2020

Cited by 11 | Viewed by 9914

Abstract

The continued dispersal of Fusarium oxysporum f. sp. cubense Tropical race 4 (FocTR4), a quarantine soil-borne pathogen that kills banana, has placed this worldwide industry on alert and triggered enormous pressure on National Plant Protection (NPOs) agencies to limit new incursions. [...] Read more.

The continued dispersal of Fusarium oxysporum f. sp. cubense Tropical race 4 (FocTR4), a quarantine soil-borne pathogen that kills banana, has placed this worldwide industry on alert and triggered enormous pressure on National Plant Protection (NPOs) agencies to limit new incursions. Accordingly, biosecurity plays an important role while long-term control strategies are developed. Aiming to strengthen the contingency response plan of Ecuador against FocTR4, a population biology study—including phylogenetics, mating type, vegetative compatibility group (VCG), and pathogenicity testing—was performed on isolates affecting local bananas, presumably associated with race 1 of F. oxysporum f. sp. cubense (Foc). Our results revealed that Foc populations in Ecuador comprise a single clonal lineage, associated with VCG0120. The lack of diversity observed in Foc populations is consistent with a single introduction event from which secondary outbreaks originated. The predominance of VCG0120, together with previous reports of its presence in Latin America countries, suggests this group as the main cause of the devastating Fusarium wilt epidemics that occurred in the 1950s associated to the demise of ‘Gros Michel’ bananas in the region. The isolates sampled from Ecuador caused disease in cultivars that are susceptible to races 1 and 2 under greenhouse experiments, although Fusarium wilt symptoms in the field were only found in ‘Gros Michel’. Isolates belonging to the same VCG0120 have historically caused disease on Cavendish cultivars in the subtropics. Overall, this study shows how Foc can be easily dispersed to other areas if restriction of contaminated materials is not well enforced. We highlight the need of major efforts on awareness and monitoring campaigns to analyze suspected cases and to contain potential first introduction events of FocTR4 in Ecuador. Full article

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16 pages, 2972 KiB

Open AccessArticle

Screening for Resistance in Farmer-Preferred Cassava Cultivars from Ghana to a Mixed Infection of CBSV and UCBSV

by Wilfred Elegba, Wilhelm Gruissem and Hervé Vanderschuren

Plants 2020, 9(8), 1026; https://doi.org/10.3390/plants9081026 - 13 Aug 2020

Cited by 8 | Viewed by 3726

Abstract

Cassava brown streak disease (CBSD) caused by the Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) is a threat to cassava production in Africa. The potential spread of CBSD into West Africa is a cause for concern, therefore screening [...] Read more.

Cassava brown streak disease (CBSD) caused by the Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) is a threat to cassava production in Africa. The potential spread of CBSD into West Africa is a cause for concern, therefore screening for resistance in farmer-preferred genotypes is crucial for effective control and management. We multiplied a selection of eleven cassava cultivars grown by farmers in Ghana to test their response to a mixed infection of CBSV (TAZ-DES-01) and UCBSV (TAZ-DES-02) isolates using a stringent top-cleft graft inoculation method. Virus titers were quantified in the inoculated scions and cuttings propagated from the inoculated scions to assess virus accumulation and recovery. All cultivars were susceptible to the mixed infection although their response and symptom development varied. In the propagated infected scions, CBSV accumulated at higher titers in leaves of eight of the eleven cultivars. Visual scoring of storage roots from six-month-old virus-inoculated plants revealed the absence of CBSD-associated necrosis symptoms and detectable titers of CBSVs in the cultivar, IFAD. Although all eleven cultivars supported the replication of CBSV and UCBSV in their leaves, the absence of virus replication and CBSD-associated symptoms in the roots of some cultivars could be used as criteria to rapidly advance durable CBSD tolerance using breeding and genetic engineering approaches. Full article

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10 pages, 1133 KiB

Open AccessArticle

Together for the Better: Improvement of a Model Based Strategy for Grapevine Downy Mildew Control by Addition of Potassium Phosphonates

by Gottfried Bleyer, Fedor Lösch, Stefan Schumacher and René Fuchs

Plants 2020, 9(6), 710; https://doi.org/10.3390/plants9060710 - 02 Jun 2020

Cited by 15 | Viewed by 2636

Abstract

Grapevine downy mildew is one of the major diseases in viticulture. To control this disease, a more effective strategy has been developed and established based on growth and model data as well as on a combination of fungicides. For this purpose, the systemic [...] Read more.

Grapevine downy mildew is one of the major diseases in viticulture. To control this disease, a more effective strategy has been developed and established based on growth and model data as well as on a combination of fungicides. For this purpose, the systemic plant protection product potassium phosphonate (PP) was combined with two contact fungicides. Treatments were carried out according to the different experimental conditions after the growth of 400 cm², 600 cm², and 800 cm² leaf area per primary shoot. PP increased the effectiveness of the preventive fungicides whenever high infection pressure was the case. The experiments also show that it is possible to extend the treatment intervals from 400 cm² to 600 cm² new leaf area when PP was added. However, none of the tested treatments were sufficient for the extension to intervals of 800 cm². These data show that PP can be a key factor in the reduction of the application of synthetic or copper-based fungicides. Full article

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16 pages, 2117 KiB

Open AccessReview

Artificial Small RNA-Based Silencing Tools for Antiviral Resistance in Plants

by Adriana E. Cisneros and Alberto Carbonell

Plants 2020, 9(6), 669; https://doi.org/10.3390/plants9060669 - 26 May 2020

Cited by 23 | Viewed by 5844

Abstract

Artificial small RNAs (art-sRNAs), such as artificial microRNAs (amiRNAs) and synthetic trans-acting small interfering RNAs (syn-tasiRNAs), are highly specific 21-nucleotide small RNAs designed to recognize and silence complementary target RNAs. Art-sRNAs are extensively used in gene function studies or for improving crops, particularly [...] Read more.

Artificial small RNAs (art-sRNAs), such as artificial microRNAs (amiRNAs) and synthetic trans-acting small interfering RNAs (syn-tasiRNAs), are highly specific 21-nucleotide small RNAs designed to recognize and silence complementary target RNAs. Art-sRNAs are extensively used in gene function studies or for improving crops, particularly to protect plants against viruses. Typically, antiviral art-sRNAs are computationally designed to target one or multiple sites in viral RNAs with high specificity, and art-sRNA constructs are generated and introduced into plants that are subsequently challenged with the target virus(es). Numerous studies have reported the successful application of art-sRNAs to induce resistance against a large number of RNA and DNA viruses in model and crop species. However, the application of art-sRNAs as an antiviral tool has limitations, such as the difficulty to predict the efficacy of a particular art-sRNA or the emergence of virus variants with mutated target sites escaping to art-sRNA-mediated degradation. Here, we review the different classes, features, and uses of art-sRNA-based tools to induce antiviral resistance in plants. We also provide strategies for the rational design of antiviral art-sRNAs and discuss the latest advances in developing art-sRNA-based methodologies for enhanced resistance to plant viruses. Full article

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