Research

15 pages, 2022 KiB

Open AccessFeature PaperArticle

Metabarcoding Reveals Impact of Different Land Uses on Fungal Diversity in the South-Eastern Region of Antioquia, Colombia

by Raul Aranguren, Samuele Voyron, Fabrizio Ungaro, Julio Cañón and Erica Lumini

Plants 2023, 12(5), 1126; https://doi.org/10.3390/plants12051126 - 02 Mar 2023

Cited by 1 | Viewed by 1499

Abstract

Changes in soil fungal communities caused by land use have not been sufficiently studied in South American Andosols, which are considered key food production areas. Since fungal communities play an important role in soil functionality, this study analysed 26 soil samples of Andosols [...] Read more.

Changes in soil fungal communities caused by land use have not been sufficiently studied in South American Andosols, which are considered key food production areas. Since fungal communities play an important role in soil functionality, this study analysed 26 soil samples of Andosols collected from locations devoted to conservation, agriculture and mining activities in Antioquia, Colombia, to establish differences between fungal communities as indicators of soil biodiversity loss using Illumina MiSeq metabarcoding on nuclear ribosomal ITS2 region. A non-metric multidimensional scaling allowed to explore driver factors of changes in fungal communities, while the significance of these variations was assessed by PERMANOVA. Furthermore, the effect size of land use over relevant taxa was quantified. Our results suggest a good coverage of fungal diversity with a detection of 353,312 high-quality ITS2 sequences. We found strong correlations of Shannon and Fisher indexes with dissimilarities on fungal communities (r = 0.94). These correlations allow grouping soil samples according to land use. Variations in temperature, air humidity and organic matter content lead to changes in abundances of relevant orders (Wallemiales and Trichosporonales). The study highlights specific sensitivities of fungal biodiversity features in tropical Andosols, which may serve as a basis for robust assessments of soil quality in the region. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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12 pages, 688 KiB

Open AccessArticle

Antifungal In Vitro Activity of Phoradendron sp. Extracts on Fungal Isolates from Tomato Crop

by Alma Leticia Salas-Gómez, César Alejandro Espinoza Ahumada, Rocío Guadalupe Castillo Godina, Juan Alberto Ascacio-Valdés, Raúl Rodríguez-Herrera, Ma. Teresa de Jesús Segura Martínez, Efraín Neri Ramírez, Benigno Estrada Drouaillet and Eduardo Osorio-Hernández

Plants 2023, 12(3), 672; https://doi.org/10.3390/plants12030672 - 03 Feb 2023

Cited by 1 | Viewed by 1783

Abstract

Synthetic chemicals are mainly used for the control of fungal diseases in tomato, causing the phytopathogens to generate resistance to the chemical active ingredient, with a consequent risk to human health and the environment. The use of plant extracts is an option for [...] Read more.

Synthetic chemicals are mainly used for the control of fungal diseases in tomato, causing the phytopathogens to generate resistance to the chemical active ingredient, with a consequent risk to human health and the environment. The use of plant extracts is an option for the control of these diseases, which is why the main objective of this research was to study an alternative biocontrol strategy for the management of plant diseases caused by fungi through obtaining polyphenol extracts from mistletoe plants growing on three different tree species—mesquite (Prosopis glandulosa), cedar (Cedrus), and oak (Quercus), which contain flavones, anthocyanins, and luteolin. The overall chemical structure of the obtained plant extracts was investigated by RP-HPLC-ESI-MS liquid chromatography. The antifungal effect of these extracts was examined. The target phytopathogenic fungi were isolated from tomato plantations located in Altamira, Tamaulipas, Mexico. The microorganisms were characterized by classical and molecular methods and identified as Alternaria alternata, Fusarium oxysporum, Fusarium sp., and Rhizoctonia solani. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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24 pages, 3424 KiB

Open AccessArticle

Arbuscular Mycorrhizal Fungi and Fertilization Influence Yield, Growth and Root Colonization of Different Tomato Genotype

by Zoltán Felföldi, Roxana Vidican, Vlad Stoian, Ioana A. Roman, Adriana F. Sestras, Teodor Rusu and Radu E. Sestras

Plants 2022, 11(13), 1743; https://doi.org/10.3390/plants11131743 - 30 Jun 2022

Cited by 10 | Viewed by 3286

Abstract

Arbuscular mycorrhizal fungi (AMF) are beneficial for plant development and help absorb water and minerals from the soil. The symbiosis between these fungi and plant roots is extremely important and could limit crop dependence on fertilizers. The aim of this study was to [...] Read more.

Arbuscular mycorrhizal fungi (AMF) are beneficial for plant development and help absorb water and minerals from the soil. The symbiosis between these fungi and plant roots is extremely important and could limit crop dependence on fertilizers. The aim of this study was to evaluate the influence of AMF on tomatoes (Solanum lycopersicum L.), based on important agronomic traits of vegetative biomass, production, and fruits. The experiment was conducted in high tunnels, using 12 tomato genotypes under three different treatments: T1, control, without fertilizer and mycorrhizae colonization; T2, fertigation, without mycorrhizae colonization; and T3, arbuscular mycorrhizal fungi (AMF), seedling roots being inoculated with specialized soil-borne fungi. Plant growth, yield and fruit parameters indicated better results under mycorrhizal treatment. Root colonization with fungi varied significantly depending on the treatment and genotype, with a variation of 6.0–80.3% for frequency and 2.6–24.6% for intensity. For a majority of characteristics, the mycorrhization (T3) induced significant differences compared with the T1 and T2 treatments. In addition, AMF treatment induced a different response among the genotypes. Among the elements analyzed in the soil, significant differences were observed in phosphorous levels between planting the seedlings and after tomato harvesting and clearing of the plants. The results suggest that reducing fertilizers and promoting the symbiotic relationships of plants with soil microorganisms may have beneficial consequences for tomato crops. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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9 pages, 1092 KiB

Open AccessCommunication

Identification and Characterization of Colletotrichum fructicola and Colletotrichum siamense Causing Anthracnose on Luffa Sponge Gourd in China

by Ping Li, Jun-Zi Zhu, Xiao-Gang Li and Jie Zhong

Plants 2022, 11(12), 1537; https://doi.org/10.3390/plants11121537 - 08 Jun 2022

Cited by 3 | Viewed by 2416

Abstract

Luffa sponge gourd (Luffa cylindrica) is an important cucurbitaceous vegetable and is known as the source of loofah. From 2020 to 2021, a leaf disease occurred on luffa leaves in the Hunan Province of China. Symptoms were displayed as oval to [...] Read more.

Luffa sponge gourd (Luffa cylindrica) is an important cucurbitaceous vegetable and is known as the source of loofah. From 2020 to 2021, a leaf disease occurred on luffa leaves in the Hunan Province of China. Symptoms were displayed as oval to irregular chlorotic lesions surrounded by yellow halos. The pathogens were isolated from the affected leaves. According to morphological characterization and molecular identification using multi-locus phylogenetic analysis of the internal transcribed spacer (ITS), actin (ACT), chitin synthase (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-tubulin (TUB2), and partial mating type (Mat1-2) gene (ApMAT) regions, the pathogens were identified as two Colletotrichum species: Colletotrichum fructicola and C. siamense. Koch’s postulates were identified by a pathogenicity test and re-confirmation. To the best of our knowledge, C. fructicola and C. siamense are two new species associated with luffa sponge gourd anthracnose. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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17 pages, 6851 KiB

Open AccessArticle

Early Growth Performance of In Vitro Raised Melia volkensii Gürke Plantlets in Response to Beneficial Microorganisms under Semi-Arid Conditions

by Constantin Dushimimana, Michael Ajanja Sakha, Mercy Jebiwott Korir, Joyce Mnyazi Jefwa, Jan Vandenabeele, Titus Magomere, Eunice Wanjiru Mutitu, Jackson Mulatya, Florence Olubayo, Guy Smagghe and Stefaan P. O. Werbrouck

Plants 2022, 11(10), 1300; https://doi.org/10.3390/plants11101300 - 13 May 2022

Viewed by 2819

Abstract

Before in vitro propagated Melia volkensii plants can be used for mass planting, the transition phase to in vivo conditions needs to be better controlled because too many plants are lost during acclimatization and in the field. Two experiments were set up to [...] Read more.

Before in vitro propagated Melia volkensii plants can be used for mass planting, the transition phase to in vivo conditions needs to be better controlled because too many plants are lost during acclimatization and in the field. Two experiments were set up to evaluate the effects of biological agents on the establishment of M. volkensii in vitro plantlets. The biological agents consisted of Trichotech^®, Bio-cure B^®, Rhizatech^®, Bacillus subtilis, a Trichoderma isolate and self-isolated native arbuscular mycorrhizal fungi (AMF). Regarding the latter, in soil from the nursery, the number of AMF spores increased from six spores to 400 per 100 g of soil using a trap culture, in which thirteen AMF morphotypes were identified and root colonization assessed through observation of hyphae, vesicles, coils and appressoria. The first experiment was set up in the greenhouse to investigate the efficacy of the biological agents on the hardening off. In the second, a field experiment was set up to study their effect on the early establishment of the plantlets in the field compared to seedlings. All biological agents significantly (p ≤ 0.05) improved in vitro plant survival and growth compared to the control. The highest plant height and number of leaves per plant were recorded in plants treated with Rhizatech^®, Native AMF, Bio-cure B^® and Trichoderma isolate. The treatments with Rhizatech^®, Bio-cure B^® and native mycorrhiza recorded a significantly wider stem. The root diameter of the plants treated with Rhizatech^® and Bio-cure B^® was the largest, but the plants inoculated with the native AMF had the longest roots. Moreover, the inoculated plants generally developed multiple secondary roots. After two months, AMF had clearly colonized the acclimatized plantlets. In the field experiment, the biologicals made no difference in survival rate but did produce a significantly larger leaf area after two months, with the largest leaves recorded with Rhizatech^®, native AMF and Trichotech^®. They also increased the quality index of the plants from 0.21 to 0.52. The performance of in vitro grown M. volkensii plants six months after planting in semi-arid conditions in Kiambere was better than that of seedlings. Inoculation of plants increased plant height and diameter. Thus, inoculation of biological agents is an efficient approach for improving the early growth of in vitro propagated M. volkensii plants. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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28 pages, 3666 KiB

Open AccessArticle

A Case Study in Saudi Arabia: Biodiversity of Maize Seed-Borne Pathogenic Fungi in Relation to Biochemical, Physiological, and Molecular Characteristics

by Abdulaziz A. Al-Askar, Khalid M. Ghoneem, Elsayed E. Hafez and WesamEldin I. A. Saber

Plants 2022, 11(6), 829; https://doi.org/10.3390/plants11060829 - 21 Mar 2022

Cited by 6 | Viewed by 3076

Abstract

Microbiodiversity is usually correlated with environmental conditions. This investigation is a case study to cover the lack of knowledge on the correlation of biochemical, physiological, and molecular attributes with the distribution of seed-borne pathogenic fungi of maize under the environmental conditions of the [...] Read more.

Microbiodiversity is usually correlated with environmental conditions. This investigation is a case study to cover the lack of knowledge on the correlation of biochemical, physiological, and molecular attributes with the distribution of seed-borne pathogenic fungi of maize under the environmental conditions of the Kingdom of Saudi Arabia to help forecast any destructive epidemics. Forty-one fungal species belonging to 24 genera were detected using standard moist blotter (SMB), deep freezing blotter (DFB), and agar plate (AP) techniques. SMB was superior in detecting the maximum numbers (36 species) of seed-borne mycoflora. The pathogenicity assay revealed that, among 18 seed-borne fungal pathogens used, 12 isolates caused high percentages of rotted seeds and seedling mortality symptoms, which were identified molecularly using an internal transcribed spacer sequence. Two Curvularia spp. and Sarocladium zeae were reported for the first time in KSA. The strains showed various enzymatic activities and amino acid profiles under different environmental setups. Temperature and humidity were the environmental variables influencing the fungal pathogenicity. The highest pathogenicity was correlated with the presence and concentration of threonine, alanine, glutamic, aspartic acids, and protein. The study concluded with the discovery of four new phytopathogens in KSA and, further, evidenced a marked correlation among the investigated variables. Nevertheless, more studies are encouraged to include additional physiological properties of the phytopathogens, such as toxigenic activity, as well as extend the fungal biodiversity study to other plants. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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12 pages, 1723 KiB

Open AccessArticle

The Integrated Effect of Microbial Inoculants and Biochar Types on Soil Biological Properties, and Plant Growth of Lettuce (Lactuca sativa L.)

by Hua Ma, Vyacheslav Shurigin, Dilfuza Jabborova, Jeane Aril dela Cruz, Thomas Edison dela Cruz, Stephan Wirth, Sonoko Dorothea Bellingrath-Kimura and Dilfuza Egamberdieva

Plants 2022, 11(3), 423; https://doi.org/10.3390/plants11030423 - 03 Feb 2022

Cited by 10 | Viewed by 3690

Abstract

Numerous reports confirm the positive effect of biochar application on soil properties and plant development. However, the interaction between root-associated beneficial microbes and different types of biochar is not well understood. The objective of this study was to evaluate the plant growth of [...] Read more.

Numerous reports confirm the positive effect of biochar application on soil properties and plant development. However, the interaction between root-associated beneficial microbes and different types of biochar is not well understood. The objective of this study was to evaluate the plant growth of lettuce after the application of three types of biochar in loamy, sandy soil individually and in combination with plant-beneficial microbes. Furthermore, total microbial activity in rhizosphere soil of lettuce was measured by means of fluorescein diacetate (FDA) hydrolase and enzyme activities linked to carbon, nitrogen, and phosphorus cycling. We used three types of biochar: (i) pyrolysis char from cherry wood (CWBC), (ii) pyrolysis char from wood (WBC), and (iii) pyrolysis char from maize (MBC) at 2% concentration. Our results showed that pyrolysis biochars positively affected plant interaction with microbial inoculants. Plant dry biomass grown on soil amended with MBC in combination with Klebsiella sp. BS13 and Klebsiella sp. BS13 + Talaromyces purpureogenus BS16aPP inoculants was significantly increased by 5.8% and 18%, respectively, compared to the control plants. Comprehensively, interaction analysis showed that the biochar effect on soil enzyme activities involved in N and P cycling depends on the type of microbial inoculant. Microbial strains exhibited plant growth-promoting traits, including the production of indole 3-acetic-acid and hydrogen cyanide and phosphate-solubilizing ability. The effect of microbial inoculant also depends on the biochar type. In summary, these findings provide new insights into the understanding of the interactions between biochar and microbial inoculants, which may affect lettuce growth and development. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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22 pages, 4339 KiB

Open AccessArticle

Mycorrhizal Patterns in the Roots of Dominant Festuca rubra in a High-Natural-Value Grassland

by Larisa Corcoz, Florin Păcurar, Victoria Pop-Moldovan, Ioana Vaida, Vlad Stoian and Roxana Vidican

Plants 2022, 11(1), 112; https://doi.org/10.3390/plants11010112 - 30 Dec 2021

Cited by 9 | Viewed by 1966

Abstract

Grassland ecosystems occupy significant areas worldwide and represent a reservoir for biodiversity. These areas are characterized by oligotrophic conditions that stimulate mycorrhizal symbiotic partnerships to meet nutritional requirements. In this study, we selected Festuca rubra for its dominance in the studied mountain grassland, [...] Read more.

Grassland ecosystems occupy significant areas worldwide and represent a reservoir for biodiversity. These areas are characterized by oligotrophic conditions that stimulate mycorrhizal symbiotic partnerships to meet nutritional requirements. In this study, we selected Festuca rubra for its dominance in the studied mountain grassland, based on the fact that grasses more easily accept a symbiotic partner. Quantification of the entire symbiosis process, both the degree of colonization and the presence of a fungal structure, was performed using the root mycorrhizal pattern method. Analysis of data normality indicated colonization frequency as the best parameter for assessing the entire mycorrhizal mechanism, with five equal levels, each of 20%. Most of the root samples showed an intensity of colonization between 0 and 20% and a maximum of arbuscules of about 5%. The colonization degree had an average value of 35%, which indicated a medium permissiveness of roots for mycorrhizal partners. Based on frequency regression models, the intensity of colonization presented high fluctuations at 50% frequency, while the arbuscule development potential was set to a maximum of 5% in mycorrhized areas. Arbuscules were limited due to the unbalanced and unequal root development and their colonizing hyphal networks. The general regression model indicated that only 20% of intra-radicular hyphae have the potential to form arbuscules. The colonization patterns of dominant species in mountain grasslands represent a necessary step for improved understanding of the symbiont strategies that sustain the stability and persistence of these species. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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17 pages, 1656 KiB

Open AccessArticle

Divergence in Corn Mycorrhizal Colonization Patterns Due to Organic Treatment

by Victoria Pop-Moldovan, Rodica Vârban, Larisa Corcoz, Anca Pleșa, Vlad Stoian and Roxana Vidican

Plants 2021, 10(12), 2760; https://doi.org/10.3390/plants10122760 - 14 Dec 2021

Cited by 2 | Viewed by 2285

Abstract

Excessive application of chemical fertilizers and other agrochemicals can cause large imbalances in soils and agricultural ecosystems. In this context, mycorrhizae represent a viable solution to mitigate these negative effects. Arbuscular mycorrhizae are vital symbionts due to the multiple benefits they bring to [...] Read more.

Excessive application of chemical fertilizers and other agrochemicals can cause large imbalances in soils and agricultural ecosystems. In this context, mycorrhizae represent a viable solution to mitigate these negative effects. Arbuscular mycorrhizae are vital symbionts due to the multiple benefits they bring to both crops and the entire agroecosystem. The main purpose of this study was to observe whether differentiated fertilization has an influence on mycorrhizal colonization patterns in corn. Observed frequencies and intensities of colonization varied widely between phenophases and treatments, with 20% variation for frequency and 14% for intensity, which implies the constant development of both partners during the vegetation period. Arbuscules and vesicles were present in all development stages, but the overall mean was lower than 4% for arbuscules and 1% for vesicles in the analyzed root fragments. Intensity was highly correlated with frequency of colonization compared with arbuscules, where the coefficient was 0.54, and vesicles, with a coefficient of 0.16. Both PCA and NMDS provided good graphical solutions, with a high resolution due to explained variance and good spatial position of vectors. The use of mycorrhizal maps permits the full exploration of colonization patterns and fungal strategy, and the assessment of mycorrhizae-free areas. For the untreated variant, the strategy was oriented toward a longitudinal colonization followed by an irregular development of hyphae with multiple non-colonized areas. Treatment acts to stimulate the appearance of mycorrhizal spots, which further develop radially. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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34 pages, 7161 KiB

Open AccessArticle

Screening and Biocontrol Potential of Rhizobacteria Native to Gangetic Plains and Hilly Regions to Induce Systemic Resistance and Promote Plant Growth in Chilli against Bacterial Wilt Disease

by Abhijeet Shankar Kashyap, Nazia Manzar, Mahendra Vikram Singh Rajawat, Amit Kumar Kesharwani, Ravinder Pal Singh, S. C. Dubey, Debasis Pattanayak, Shri Dhar, S. K. Lal and Dinesh Singh

Plants 2021, 10(10), 2125; https://doi.org/10.3390/plants10102125 - 07 Oct 2021

Cited by 32 | Viewed by 4020

Abstract

Plant growth-promoting rhizobacteria (PGPR) is a microbial population found in the rhizosphere of plants that can stimulate plant development and restrict the growth of plant diseases directly or indirectly. In this study, 90 rhizospheric soil samples from five agro climatic zones of chilli [...] Read more.

Plant growth-promoting rhizobacteria (PGPR) is a microbial population found in the rhizosphere of plants that can stimulate plant development and restrict the growth of plant diseases directly or indirectly. In this study, 90 rhizospheric soil samples from five agro climatic zones of chilli (Capsicum annuum L.) were collected and rhizobacteria were isolated, screened and characterized at morphological, biochemical and molecular levels. In total, 38% of rhizobacteria exhibited the antagonistic capacity to suppress Ralstonia solanacearum growth and showed PGPR activities such as indole acetic acid production by 67.64% from total screened rhizobacteria isolates, phosphorus solubilization by 79.41%, ammonia by 67.75%, HCN by 58.82% and siderophore by 55.88%. We performed a principal component analysis depicting correlation and significance among plant growth-promoting activities, growth parameters of chilli and rhizobacterial strains. Plant inoculation studies indicated a significant increase in growth parameters and PDS1 strain showed maximum 71.11% biocontrol efficiency against wilt disease. The best five rhizobacterial isolates demonstrating both plant growth-promotion traits and biocontrol potential were characterized and identified as PDS1—Pseudomonas fluorescens (MN368159), BDS1—Bacillus subtilis (MN395039), UK4—Bacillus cereus (MT491099), UK2—Bacillus amyloliquefaciens (MT491100) and KA9—Bacillus subtilis (MT491101). These rhizobacteria have the potential natural elicitors to be used as biopesticides and biofertilizers to improve crop health while warding off soil-borne pathogens. The chilli cv. Pusa Jwala treated with Bacillus subtilis KA9 and Pseudomonas fluorescens PDS1 showed enhancement in the defensive enzymes PO, PPO, SOD and PAL activities in chilli leaf and root tissues, which collectively contributed to induced resistance in chilli plants against Ralstonia solanacearum. The induction of these defense enzymes was found higher in leave tissues (PO—4.87-fold, PP0—9.30-fold, SOD—9.49-fold and PAL—1.04-fold, respectively) in comparison to roots tissue at 48 h after pathogen inoculation. The findings support the view that plant growth-promoting rhizobacteria boost defense-related enzymes and limit pathogen growth in chilli plants, respectively, hence managing the chilli bacterial wilt. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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11 pages, 1820 KiB

Open AccessCommunication

Identification and First Report of Fusarium andiyazi Causing Sheath Rot of Zizania latifolia in China

by Ya-Min Ma, Jun-Zi Zhu, Xiao-Gang Li, Lai-Liang Wang and Jie Zhong

Plants 2021, 10(9), 1844; https://doi.org/10.3390/plants10091844 - 06 Sep 2021

Cited by 1 | Viewed by 2711

Abstract

Zizania latifolia is a perennial plant native to East Asia. The swollen culm of Z. latifolia is a popular vegetable and traditional herbal medicine consumed in China and some other Asian countries. From 2019 to 2021, a sheath rot disease was found in [...] Read more.

Zizania latifolia is a perennial plant native to East Asia. The swollen culm of Z. latifolia is a popular vegetable and traditional herbal medicine consumed in China and some other Asian countries. From 2019 to 2021, a sheath rot disease was found in Zhejiang Province of China. Symptoms mainly occurred in the leaf sheath showing as brown necrotic lesions surrounded by yellow halos. The pathogen fungal isolates were isolated from the affected sheaths. Ten representative isolates were selected for morphological and molecular identification by phylogenetic analyses of the translation elongation factor 1-α (TEF1) and the RNA polymerase II subunit beta (RPB2) gene regions. Based on the combined datasets, the fungal isolates were identified as Fusarium andiyazi. Koch’s postulates were confirmed by pathogenicity test, re-isolation and re-identification of the fungal isolates. To the best of our knowledge, this is the first report of sheath rot caused by F. andiyazi in Z. latifolia in China. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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28 pages, 5529 KiB

Open AccessEditor’s ChoiceReview

The Use of PGPB to Promote Plant Hydroponic Growth

by Ashley A. Stegelmeier, Danielle M. Rose, Benjamin R. Joris and Bernard R. Glick

Plants 2022, 11(20), 2783; https://doi.org/10.3390/plants11202783 - 20 Oct 2022

Cited by 21 | Viewed by 8322

Abstract

Improvements to the world’s food supply chain are needed to ensure sufficient food is produced to meet increasing population demands. Growing food in soilless hydroponic systems constitutes a promising strategy, as this method utilizes significantly less water than conventional agriculture, can be situated [...] Read more.

Improvements to the world’s food supply chain are needed to ensure sufficient food is produced to meet increasing population demands. Growing food in soilless hydroponic systems constitutes a promising strategy, as this method utilizes significantly less water than conventional agriculture, can be situated in urban areas, and can be stacked vertically to increase yields per acre. However, further research is needed to optimize crop yields in these systems. One method to increase hydroponic plant yields involves adding plant growth-promoting bacteria (PGPB) into these systems. PGPB are organisms that can significantly increase crop yields via a wide range of mechanisms, including stress reduction, increases in nutrient uptake, plant hormone modulation, and biocontrol. The aim of this review is to provide critical information for researchers on the current state of the use of PGPB in hydroponics so that meaningful advances can be made. An overview of the history and types of hydroponic systems is provided, followed by an overview of known PGPB mechanisms. Finally, examples of PGPB research that has been conducted in hydroponic systems are described. Amalgamating the current state of knowledge should ensure that future experiments can be designed to effectively transition results from the lab to the farm/producer, and the consumer. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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20 pages, 8240 KiB

Open AccessProject Report

Tobacco Plant Growth-Promoting and Antifungal Activities of Three Endophytic Yeast Strains

by Mariana Petkova, Slaveya Petrova, Velichka Spasova-Apostolova and Mladen Naydenov

Plants 2022, 11(6), 751; https://doi.org/10.3390/plants11060751 - 11 Mar 2022

Cited by 12 | Viewed by 3199

Abstract

In this research, the biosynthetic and biocontrol potential of endophytic yeast to improve the growth and development of tobacco has been elucidated. Three yeast strains were enriched and isolated from different plant tissues. Partial sequence analysis of ITS5-5.8-ITS4 region of the nuclear ribosomal [...] Read more.

In this research, the biosynthetic and biocontrol potential of endophytic yeast to improve the growth and development of tobacco has been elucidated. Three yeast strains were enriched and isolated from different plant tissues. Partial sequence analysis of ITS5-5.8-ITS4 region of the nuclear ribosomal DNA with universal primers identified YD5, YE1, and YSW1 as Saccharomyces cerevisiae (S. cerevisiae), Zygosaccharomyces bailii (Z. bailii), and Saccharomyces kudriavzevii (S. kudriavzevii), respectively. When cultivated in a medium supplemented with 0.1% L-tryptophan, isolated yeast strains produced indole-3-acetic acid (IAA). The capacities of those strains to improve the mobility of phosphorus and synthesize siderophores has been proven. Their antimicrobial activities against several Solanaceae plant pathogenic fungi (Alternaria solani pathovar. tobacco, Rhizoctonia solani, and Fusarium solani pathovar. phaseoli) were determined. S. cerevisiae YD5, Z. bailii YE1, and S. kudriavzevii YSW1 inhibited the growth of all tested pathogens. Yeast strains were tested for endophytic colonization of tobacco by two different inoculation methods: soil drench (SD) and leaf spraying (LS). To establish colonization in the various tissues of tested tobacco (Nicotiana tabaccum L.) plants, samples were taken on the seventh, fourteenth, and twenty-first days after treatment (DAT), and explants were inoculated on yeast malt agar (YMA). Both techniques of inoculation showed a high frequency of colonization from 83.33% to 100%. To determine the effectiveness of the microbial endophytes, their effect on some physiological processes in the plant were analyzed, such as photosynthesis, stomatal conductivity, and transpiration intensity. The effect of single and double treatment with yeast inoculum on the development and biochemical parameters of tobacco was reported. Plants have the ability of structural and functional adaptation to stress effects of different natures. All treated plants had a higher content of photosynthetic pigments compared to the control. Photosynthesis is probably more intense, and growth stimulation has been observed. The chlorophyll a/b ratio remained similar, and the total chlorophyll/carotenoid ratio slightly increased as a result of elevated chlorophyll levels. The most significant stimulating effect was recorded in tobacco plants treated by foliar spraying with Z. bailii YE1 and S. cerevisiae YD5. In contrast, S. kudriavzevii YSW1 had a better effect when applied as a soil drench. Thus, S. cerevisiae YD5, Z. bailii YE1, and S. kudriavzevii YSW1 have a high potential to be used as a biocontrol agents in organic agriculture. Full article

(This article belongs to the Special Issue Agricultural Microbiology)

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