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11 pages, 5046 KiB

Open AccessArticle

Fungal Pathogens of Cacao in Puerto Rico

by Alina Sandra Puig

Plants 2023, 12(22), 3855; https://doi.org/10.3390/plants12223855 - 15 Nov 2023

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Cacao production is a rapidly expanding industry in Puerto Rico, with new farmers planting ~20,000 trees in the past few years. To determine the etiology and extent of diseases affecting cacao in Puerto Rico, a survey was performed at eight sites around the [...] Read more.

Cacao production is a rapidly expanding industry in Puerto Rico, with new farmers planting ~20,000 trees in the past few years. To determine the etiology and extent of diseases affecting cacao in Puerto Rico, a survey was performed at eight sites around the island. Pod rot and/or branch dieback were observed at all sites. Most organisms isolated from symptomatic pod and stem samples were identified as Diaporthe spp. (48%) and Lasiodiplodia spp. (25%) based on sequences of the internal transcribed spacer and large subunit regions. Within these genera, Diaporthe tulliensis and Lasiodiplodia theobromae were the most prevalent species and were used in inoculation studies to determine their relative virulence on pods and stems. Phytophthora palmivora served as a positive control due to its well-established pathogenicity in all tissues. On pods, L. theobromae and P. palmivora caused significantly larger lesions (6.1 and 5.9 cm, respectively) than D. tulliensis (2.7 cm) four days post-inoculation. All three species caused disease on stems, with no differences found among species. Although P. palmivora was thought to be the primary pathogen affecting cacao in Puerto Rico, this study identifies L. theobromae and D. tulliensis as the common pathogens on the island. This improved understanding will help scientists and farmers control disease by selecting fungicides effective against both oomycetes and fungi. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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8 pages, 465 KiB

Open AccessCommunication

Resistant or Susceptible? How Central European Oat (A. sativa L.) Cultivars React to B. graminis f. sp. avenae Infection

by Magdalena Cieplak and Sylwia Okoń

Plants 2023, 12(22), 3825; https://doi.org/10.3390/plants12223825 - 11 Nov 2023

Viewed by 538

Abstract

In accordance with the postulates of integrated plant protection, the use of cultivars with genetically determined resistance is one of the main strategies for preventing losses caused by fungal pathogens. The development of breeding programs aimed at increasing resistance to pathogens should be [...] Read more.

In accordance with the postulates of integrated plant protection, the use of cultivars with genetically determined resistance is one of the main strategies for preventing losses caused by fungal pathogens. The development of breeding programs aimed at increasing resistance to pathogens should be preceded by a characterization of the resistance of cultivars grown in a given area. This allows us to determine the number of genes used in breeding and their effectiveness. It also allows us to estimate the pressure that the pathogen may exert on varieties with specific resistance genes. The presented work aimed to determine the level of resistance of oat varieties currently cultivated in Central Europe and the number of effective powdery mildew resistance genes currently used in oat breeding programs. The research showed that out of 46 varieties, only 5 were resistant to powdery mildew. Analysis of the infection profiles allowed us to postulate the presence of the Pm7 gene in four of them. In the Merlin variety from the Czech Republic, it was not possible to determine which of the previously described genes determines resistance to powdery mildew. Due to the observed climate changes and the rapid adaptation of pathogens to new environmental conditions, it is crucial to introduce a wider pool of genes that determine the pathogen resistance of cultivars. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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25 pages, 4665 KiB

Open AccessArticle

Comparative Study of Three Biological Control Agents and Two Conventional Fungicides against Coriander Damping-off and Root Rot Caused by Rhizoctonia solani

by Abdelrazek S. Abdelrhim, Yasmin M. R. Abdellatif, Mohammad A. Hossain, Saud Alamri, Mohammad Pessarakli, Amna M. N. Lessy and Mona F. A. Dawood

Plants 2023, 12(8), 1694; https://doi.org/10.3390/plants12081694 - 18 Apr 2023

Cited by 3 | Viewed by 1946

Abstract

The in vitro and in vivo efficacy of three biocontrol agents, Trichoderma viride, Pseudomonas fluorescence, and Bacillus subtilis, were tested against Rhizoctonia solani (AG-4) infection compared to two conventional fungicides (Rizolex-T 50%wettable powder and Amistar 25%). Antifungal enzyme activity was [...] Read more.

The in vitro and in vivo efficacy of three biocontrol agents, Trichoderma viride, Pseudomonas fluorescence, and Bacillus subtilis, were tested against Rhizoctonia solani (AG-4) infection compared to two conventional fungicides (Rizolex-T 50%wettable powder and Amistar 25%). Antifungal enzyme activity was assayed in the culture filtrate of the biocontrol agents. The impact of the tested biocontrol agents on the induction of the coriander immune system was investigated against R. solani by assessing the resistance-related enzymes and compounds in biocontrol agent-treated plants compared with the control. The obtained results revealed that all tested biocontrol agents significantly reduced the linear growth of R. solani, and T. viride recorded the highest inhibition percentage. This could be linked to the ability of T. viride to produce higher activities of antimicrobial enzymes, i.e., cellulase, chitinase, and protease, compared to P. fluorescence and B. subtilis. Applying the tested biocontrol agents significantly alleviated pre- and post-emergence damping-off and root rot/wilt diseases of infected coriander compared with untreated plants. The tested biocontrol agents exhibited significantly higher germination percentage and vigor index of the coriander than the tested fungicides. The tested biocontrol agents significantly minimized the reduction of photosynthetic pigments induced by R. solani. In addition, the results showed a significant increase in enzymes/molecules (i.e., phenylalanine, catalase, peroxidase, catalase, superoxide dismutase, phenylalanine ammonia-lyase, phenolics, ascorbic acids, and salicylic acid) involved directly and indirectly in coriander resistance to R. solani. The principal component analysis of the recorded data recommended the role of the high accumulation of oxidative parameters (hydrogen peroxide and lipid peroxidation) and the inhibition of phenolic compounds in the downregulation of coriander resistance against R. solani. The heatmap analysis results revealed that biocontrol agents, especially Trichoderma, enhanced the resistance against R. solani via the stimulation of salicylic acid, phenolics, and antioxidant enzymes. Overall, the data recommended the efficacy of biocontrol agents, especially T. viride, against R. solani infecting coriander plants, which could be an efficient and a safer alternative to conventional fungicides. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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11 pages, 10752 KiB

Open AccessArticle

Detection, Identification and Molecular Characterization of the 16SrII-V Subgroup Phytoplasma Strain Associated with Pisum sativum and Parthenium hysterophorus L.

by Yi-Ching Chiu, Pei-Qing Liao, Helen Mae Mejia, Ya-Chien Lee, Yuh-Kun Chen and Jun-Yi Yang

Plants 2023, 12(4), 891; https://doi.org/10.3390/plants12040891 - 16 Feb 2023

Cited by 1 | Viewed by 1494

Abstract

Two unrelated plant species, green pea and parthenium weed, harboring typical phytoplasma symptoms, were discovered in Yunlin, Taiwan. Green pea (Pisum sativum.) and parthenium weed (Parthenium hysterophorus L.) are both herbaceous annual plants belonging to the Fabaceae and Asteraceae families, [...] Read more.

Two unrelated plant species, green pea and parthenium weed, harboring typical phytoplasma symptoms, were discovered in Yunlin, Taiwan. Green pea (Pisum sativum.) and parthenium weed (Parthenium hysterophorus L.) are both herbaceous annual plants belonging to the Fabaceae and Asteraceae families, respectively. Displayed symptoms were witches’ broom, phyllody and virescence, which are typical indications of phytoplasma infection. Pleomorphic phytoplasma-like bodies were observed under the transmission electron microscope in the sieve elements of symptomatic green pea and parthenium weed. The iPhyClassifier-based virtual RFLP study demonstrated that the phytoplasma associated with the diseased plants belongs to the 16SrII-V subgroup. The disease symptoms of both plants can be explained by the identification of PHYL1 and SAP11 effectors, identical to those of peanut witches’ broom phytoplasma. The phytoplasma strains identified in this study present a very close phylogenetic relationship with other 16SrII-V subgroup phytoplasma strains discovered in Taiwan. These results not only convey the local status of the 16SrII-V subgroup phytoplasma strains but also encourage attention to be given to preventing the spread of this threat before it becomes pervasive. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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15 pages, 2809 KiB

Open AccessArticle

Morphology and Phylogeny Reveal Three Montagnula Species from China and Thailand

by Ya-Ru Sun, Jing-Yi Zhang, Kevin D. Hyde, Yong Wang and Ruvishika S. Jayawardena

Plants 2023, 12(4), 738; https://doi.org/10.3390/plants12040738 - 07 Feb 2023

Cited by 6 | Viewed by 1292

Abstract

Four stains were isolated from two fresh twigs of Helwingia himalaica and two dead woods during investigations of micro-fungi in China and Thailand. Phylogenetic analyses of four gene regions LSU, ITS, SSU and tef1-α revealed the placement of these species in Montagnula [...] Read more.

Four stains were isolated from two fresh twigs of Helwingia himalaica and two dead woods during investigations of micro-fungi in China and Thailand. Phylogenetic analyses of four gene regions LSU, ITS, SSU and tef1-α revealed the placement of these species in Montagnula. Based on the morphological examination and molecular data, two new species, M. aquatica and M. guiyangensis, and a known species M. donacina are described. Descriptions and illustrations of the new collections and a key to the Montagnula species are provided. Montagnula chromolaenicola, M. puerensis, M. saikhuensis, and M. thailandica are discussed and synonymized under M. donacina. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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60 pages, 29104 KiB

Open AccessArticle

Taxonomic Advances from Fungal Flora Associated with Ferns and Fern-like Hosts in Northern Thailand

by Elaheh Seifollahi, Antonio Roberto Gomes de Farias, Ruvishika Shehali Jayawardena and Kevin D. Hyde

Plants 2023, 12(3), 683; https://doi.org/10.3390/plants12030683 - 03 Feb 2023

Cited by 2 | Viewed by 2027

Abstract

Ferns are one of the most significant plant groupings that comprise a substantial proportion of the plant flora due to the fact of their great diversity, especially in tropical areas. The biodiversity of fungi associated with ferns and fern-like hosts has also received [...] Read more.

Ferns are one of the most significant plant groupings that comprise a substantial proportion of the plant flora due to the fact of their great diversity, especially in tropical areas. The biodiversity of fungi associated with ferns and fern-like hosts has also received little attention in studies. Plant samples were collected from diseased and dead plants of ten fern or fern-like species from Chiang Rai in northern Thailand. Forty-one isolates were selected from the obtained isolates for molecular and morphological analysis, with a focus on pathogenic fungal genera and consideration of the diversity in host and geographical location. Twenty-six species belonging to seven genera (Colletotrichum, Curvularia, Diaporthe, Fusarium, Lasiodiplodia, Neopestalotiopsis, and Pestalotiopsis) in six families were identified. Thirty new hosts, eight new geographical hosts, and one new species, Colletotrichum polypodialium, are described. Nepestalotiopsis phangngaensis, N. pandancola, Diaporthe tectonendophytica, D. chiangraiensis, and D. delonicis were isolated for the first time from leaf spots. Additionally, new reservoirs and geographical locations for species previously isolated from leaf spots or whose pathogenicity was established were found. However, more studies are necessary to prove the pathogenicity of the fungi isolated from the leaf spots and to identify the fungi associated with other species of ferns. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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14 pages, 5422 KiB

Open AccessArticle

Fusarium Species Associated with Cherry Leaf Spot in China

by Yueyan Zhou, Wei Zhang, Xinghong Li, Shuxian Ji, Kandawatte Wedaralalage Thilini Chethana, Kevin David Hyde and Jiye Yan

Plants 2022, 11(20), 2760; https://doi.org/10.3390/plants11202760 - 19 Oct 2022

Cited by 5 | Viewed by 2135

Abstract

Sweet cherry is an important fruit crop in China with a high economic value. From 2019 to 2020, a leaf spot disease was reported, with purplish-brown circular lesions in three cultivating regions in China. Twenty-four Fusarium isolates were obtained from diseased samples and [...] Read more.

Sweet cherry is an important fruit crop in China with a high economic value. From 2019 to 2020, a leaf spot disease was reported, with purplish-brown circular lesions in three cultivating regions in China. Twenty-four Fusarium isolates were obtained from diseased samples and were identified based on morphological characteristics and multi-locus phylogenetic analyses. Seven species, including F. luffae (7 isolates), F. lateritium (6 isolates), F. compactum (5 isolates), F. nygamai (2 isolates), F. citri (2 isolates), F. ipomoeae (1 isolate) and F. curvatum (1 isolate) were identified. The pathogenicity test showed that analyzed strains of all species could produce lesions on detached cherry leaves. Therefore, Fusarium was proved to be a pathogen of cherry leaf spots in China. This is the first report of F. luffae, F. compactum, F. nygamai, F. citri, F. ipomoeae and F. curvatum on sweet cherry in China. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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11 pages, 1706 KiB

Open AccessArticle

An NmrA-Like Protein, Lws1, Is Important for Pathogenesis in the Woody Plant Pathogen Lasiodiplodia theobromae

by Junbo Peng, Janith V. S. Aluthmuhandiram, K. W. Thilini Chethana, Qi Zhang, Qikai Xing, Hui Wang, Mei Liu, Wei Zhang, Xinghong Li and Jiye Yan

Plants 2022, 11(17), 2197; https://doi.org/10.3390/plants11172197 - 24 Aug 2022

Cited by 5 | Viewed by 1577

Abstract

The NmrA-like proteins have been reported to be important nitrogen metabolism regulators and virulence factors in herbaceous plant pathogens. However, their role in the woody plant pathogen Lasiodiplodia theobromae is less clear. In the current study, we identified a putative NmrA-like protein, Lws1, [...] Read more.

The NmrA-like proteins have been reported to be important nitrogen metabolism regulators and virulence factors in herbaceous plant pathogens. However, their role in the woody plant pathogen Lasiodiplodia theobromae is less clear. In the current study, we identified a putative NmrA-like protein, Lws1, in L. theobromae and investigated its pathogenic role via gene silencing and overexpression experiments. We also evaluated the effects of external carbon and nitrogen sources on Lws1 gene expression via qRT-PCR assays. Moreover, we analyzed the molecular interaction between Lws1 and its target protein via the yeast two-hybrid system. The results show that Lws1 contained a canonical glycine-rich motif shared by the short-chain dehydrogenase/reductase (SDR) superfamily proteins and functioned as a negative regulator during disease development. Transcription profiling revealed that the transcription of Lws1 was affected by external nitrogen and carbon sources. Interaction analyses demonstrated that Lws1 interacted with a putative GATA family transcription factor, LtAreA. In conclusion, these results suggest that Lws1 serves as a critical regulator in nutrition metabolism and disease development during infection. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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14 pages, 516 KiB

Open AccessArticle

A Comparison of Three Types of “Vineyard Management” and Their Effects on the Structure of Plasmopara viticola Populations and Epidemic Dynamics of Grape Downy Mildew

by Shuyi Yu, Baihong Li, Tianshu Guan, Li Liu, Hui Wang, Changyuan Liu, Chaoqun Zang, Yuqian Huang and Chunhao Liang

Plants 2022, 11(16), 2175; https://doi.org/10.3390/plants11162175 - 21 Aug 2022

Cited by 3 | Viewed by 1484

Abstract

Grape downy mildew (GDM) is a destructive grapevine disease caused by Plasmopara viticola that occurs worldwide. In this study, we determined the characteristics of GDM epidemics and the grapevine canopy micro-climate in open-field, fungicide-spray, and rain-shelter plots during two constitutive years (2016 and [...] Read more.

Grape downy mildew (GDM) is a destructive grapevine disease caused by Plasmopara viticola that occurs worldwide. In this study, we determined the characteristics of GDM epidemics and the grapevine canopy micro-climate in open-field, fungicide-spray, and rain-shelter plots during two constitutive years (2016 and 2017). It was found that rain shelter can significantly delay the disease occurrence by 28 and 21 days, reduce the epidemic phase by 28 and 21 days, and decrease the final disease index by 82% and 83%. Furthermore, it can block precipitation, reduce the relative humidity by 11% and 8%, and reduce the leaf wetness duration by 85% and 76% compared with open-field cultivation. A total of 3861, 783, and 1145 lesions were collected from the open-field, fungicide-managed, and rain-shelter plots, respectively, for analyses of the genetic diversity, population differentiation, and epidemic mode with seven microsatellite markers. In terms of genetic diversity, the Nei’s diversity index ranged from 0.569 to 0.680 and Shannon’s information index ranged from 0.958 to 1.226, showing high levels of diversity across populations. Similar to fungicide management, a rain shelter can significantly reduce the population’s genetic diversity. Low pairwise FST values (0.003–0.047) and high gene flow (Nm = 1.548–20.699) were observed among the three populations each year. In addition, most of the genetic variation occurred within populations. The epidemic mode of GDM in the open-field, fungicide-managed, and rain-shelter cultivation showed moderate, low, and high levels of clonality, respectively, in the case study. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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14 pages, 3701 KiB

Open AccessBrief Report

First Report of Colletotrichum fructicola Causing Fruit Rot and Leaf-Tip Dieback on Pineapple in Northern Thailand

by Alireza Armand, Kevin David Hyde and Ruvishika Shehali Jayawardena

Plants 2023, 12(4), 971; https://doi.org/10.3390/plants12040971 - 20 Feb 2023

Cited by 3 | Viewed by 2459

Abstract

Pineapple is one of the most economically important fruits in tropical countries, particularly in Thailand. Canned pineapple is currently Thailand’s main exported commodity to many countries, including the United States, Russia, Germany, Poland, and Japan. Fungal diseases are considered a permanent threat to [...] Read more.

Pineapple is one of the most economically important fruits in tropical countries, particularly in Thailand. Canned pineapple is currently Thailand’s main exported commodity to many countries, including the United States, Russia, Germany, Poland, and Japan. Fungal diseases are considered a permanent threat to fruits in the pre- and post-harvest stages, leading to considerable economic losses. Fungal disease is one of the primary causes of massive yield losses in pineapples around the world. Colletotrichum species are the most common fungal pathogens affecting different tropical fruits. Although there are many reports regarding Colletotrichum species associated with pineapple, they do not have molecular data to confirm species identification. However, the occurrence of Colletotrichum species on pineapple has not been reported in Thailand so far. In this study, we isolated and identified Colletotrichum fructicola on pineapple in northern Thailand and have proven its pathogenicity to the host. This is the first report of the occurrence of Colletotrichum in pineapple, based on morpho-molecular approaches. Full article

(This article belongs to the Special Issue The Research of Plant Fungal Disease)

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