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Miller SA, Testen AL, Jacobs JM, Ivey MLL. Mitigating Emerging and Reemerging Diseases of Fruit and Vegetable Crops in a Changing Climate. PHYTOPATHOLOGY 2024; 114:917-929. [PMID: 38170665 DOI: 10.1094/phyto-10-23-0393-kc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Fruit and vegetable crops are important sources of nutrition and income globally. Producing these high-value crops requires significant investment of often scarce resources, and, therefore, the risks associated with climate change and accompanying disease pressures are especially important. Climate change influences the occurrence and pressure of plant diseases, enabling new pathogens to emerge and old enemies to reemerge. Specific environmental changes attributed to climate change, particularly temperature fluctuations and intense rainfall events, greatly alter fruit and vegetable disease incidence and severity. In turn, fruit and vegetable microbiomes, and subsequently overall plant health, are also affected by climate change. Changing disease pressures cause growers and researchers to reassess disease management and climate change adaptation strategies. Approaches such as climate smart integrated pest management, smart sprayer technology, protected culture cultivation, advanced diagnostics, and new soilborne disease management strategies are providing new tools for specialty crops growers. Researchers and educators need to work closely with growers to establish fruit and vegetable production systems that are resilient and responsive to changing climates. This review explores the effects of climate change on specialty food crops, pathogens, insect vectors, and pathosystems, as well as adaptations needed to ensure optimal plant health and environmental and economic sustainability.
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Affiliation(s)
- Sally A Miller
- Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
| | - Anna L Testen
- U.S. Department of Agriculture-Agricultural Research Service Application Technology Research Unit, Wooster, OH 44691
| | - Jonathan M Jacobs
- Department of Plant Pathology, The Ohio State University, Columbus, OH 43210
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Fletcher K, Michelmore R. Genome-Enabled Insights into Downy Mildew Biology and Evolution. ANNUAL REVIEW OF PHYTOPATHOLOGY 2023; 61:165-183. [PMID: 37268005 DOI: 10.1146/annurev-phyto-021622-103440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Oomycetes that cause downy mildew diseases are highly specialized, obligately biotrophic phytopathogens that can have major impacts on agriculture and natural ecosystems. Deciphering the genome sequence of these organisms provides foundational tools to study and deploy control strategies against downy mildew pathogens (DMPs). The recent telomere-to-telomere genome assembly of the DMP Peronospora effusa revealed high levels of synteny with distantly related DMPs, higher than expected repeat content, and previously undescribed architectures. This provides a road map for generating similar high-quality genome assemblies for other oomycetes. This review discusses biological insights made using this and other assemblies, including ancestral chromosome architecture, modes of sexual and asexual variation, the occurrence of heterokaryosis, candidate gene identification, functional validation, and population dynamics. We also discuss future avenues of research likely to be fruitful in studies of DMPs and highlight resources necessary for advancing our understanding and ability to forecast and control disease outbreaks.
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Affiliation(s)
- Kyle Fletcher
- The Genome Center, University of California, Davis, California, USA
| | - Richard Michelmore
- The Genome Center, University of California, Davis, California, USA
- Department of Plant Sciences; Department of Molecular and Cellular Biology; Department of Medical Microbiology and Immunology, University of California, Davis, California, USA;
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Greer SF, Surendran A, Grant M, Lillywhite R. The current status, challenges, and future perspectives for managing diseases of brassicas. Front Microbiol 2023; 14:1209258. [PMID: 37533829 PMCID: PMC10392840 DOI: 10.3389/fmicb.2023.1209258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 06/23/2023] [Indexed: 08/04/2023] Open
Abstract
The Brassica genus comprises the greatest diversity of agriculturally important crops. Several species from this genus are grown as vegetable and oil crops for food, animal feed and industrial purposes. In particular, B. oleracea has been extensively bred to give rise to several familiar vegetables (cabbage, broccoli, cauliflower, kale and Brussels Sprouts, etc.) that are grouped under seven major cultivars. In 2020, 96.4 million tonnes of vegetable brassicas were produced globally with a 10.6% increase over the past decade. Yet, like other crops, the production of brassicas is challenged by diseases among which, black rot, clubroot, downy mildew and turnip yellows virus have been identified by growers as the most damaging to UK production. In some cases, yield losses can reach 90% depending upon the geographic location of cultivation. This review aims to provide an overview of the key diseases of brassicas and their management practices, with respect to the biology and lifecycle of the causal pathogens. In addition, the existing controls on the market as well as those that are currently in the research and development phases were critically reviewed. There is not one specific control method that is effective against all the diseases. Generally, cultural practices prevent disease rather than reduce or eliminate disease. Chemical controls are limited, have broad-spectrum activity, are damaging to the environment and are rapidly becoming ineffective due to the evolution of resistance mechanisms by the pathogens. It is therefore important to develop integrated pest management (IPM) strategies that are tailored to geographic locations. Several knowledge gaps have been identified and listed in this review along with the future recommendations to control these four major diseases of brassicas. As such, this review paper will act as a guide to sustainably tackle pre-harvest diseases in Brassica crops to reduce food loss.
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Affiliation(s)
- Shannon F. Greer
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Arthy Surendran
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
- Carbon, Crop and Soils Group, SRUC, Edinburgh, United Kingdom
| | - Murray Grant
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Robert Lillywhite
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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D'Arcangelo KN, Wallace EC, Miles TD, Quesada-Ocampo LM. Carboxylic Acid Amide but Not Quinone Outside Inhibitor Fungicide Resistance Mutations Show Clade-Specific Occurrence in Pseudoperonospora cubensis Causing Downy Mildew in Commercial and Wild Cucurbits. PHYTOPATHOLOGY 2023; 113:80-89. [PMID: 35918851 DOI: 10.1094/phyto-05-22-0166-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Since its reemergence in 2004, Pseudoperonospora cubensis, the causal agent of cucurbit downy mildew (CDM), has experienced significant changes in fungicide sensitivity. Presently, frequent fungicide applications are required to control the disease in cucumber due to the loss of host resistance. Carboxylic acid amides (CAA) and quinone outside inhibitors (QoI) are two fungicide groups used to control foliar diseases in cucurbits, including CDM. Resistance to these fungicides is associated with single nucleotide polymorphism (SNP) mutations. In this study, we used population analyses to determine the occurrence of fungicide resistance mutations to CAA and QoI fungicides in host-adapted clade 1 and clade 2 P. cubensis isolates. Our results revealed that CAA-resistant genotypes occurred more prominently in clade 2 isolates, with more sensitive genotypes observed in clade 1 isolates, while QoI resistance was widespread across isolates from both clades. We also determined that wild cucurbits can serve as reservoirs for P. cubensis isolates containing fungicide resistance alleles. Finally, we report that the G1105W substitution associated with CAA resistance was more prominent within clade 2 P. cubensis isolates while the G1105V resistance substitution and sensitivity genotypes were more prominent in clade 1 isolates. Our findings of clade-specific occurrence of fungicide resistance mutations highlight the importance of understanding the population dynamics of P. cubensis clades by crop and region to design effective fungicide programs and establish accurate baseline sensitivity to active ingredients in P. cubensis populations.
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Affiliation(s)
- K N D'Arcangelo
- Department of Entomology and Plant Pathology and NC Plant Sciences Initiative, North Carolina State University, Raleigh, NC 27606-7825
| | - E C Wallace
- Department of Entomology and Plant Pathology and NC Plant Sciences Initiative, North Carolina State University, Raleigh, NC 27606-7825
| | - T D Miles
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - L M Quesada-Ocampo
- Department of Entomology and Plant Pathology and NC Plant Sciences Initiative, North Carolina State University, Raleigh, NC 27606-7825
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Cherrad S, Gillet B, Dellinger J, Bellaton L, Roux P, Hernandez C, Steva H, Perrier L, Vacher S, Hughes S. New insights from short and long reads sequencing to explore cytochrome b variants in Plasmopara viticola populations collected from vineyards and related to resistance to complex III inhibitors. PLoS One 2023; 18:e0268385. [PMID: 36656908 PMCID: PMC9851517 DOI: 10.1371/journal.pone.0268385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 12/27/2022] [Indexed: 01/20/2023] Open
Abstract
Downy mildew is caused by Plasmopara viticola, an obligate oomycete plant pathogen, a devasting disease of grapevine. To protect plants from the disease, complex III inhibitors are among the fungicides widely used. They specifically target the mitochondrial cytochrome b (cytb) of the pathogen to block cellular respiration mechanisms. In the French vineyard, P. viticola has developed resistance against a first group of these fungicides, the Quinone outside Inhibitors (QoI), with a single amino acid substitution G143A in its cytb mitochondrial sequence. The use of QoI was limited and another type of fungicide, the Quinone inside Inhibitors, targeting the same gene and highly effective against oomycetes, was used instead. Recently however, less sensitive P. viticola populations were detected after treatments with some inhibitors, in particular ametoctradin and cyazofamid. By isolating single-sporangia P. viticola strains resistant to these fungicides, we characterized new variants in the cytb sequences associated with cyazofamid resistance: a point mutation (L201S) and more strikingly, two insertions (E203-DE-V204, E203-VE-V204). In parallel with the classical tools, pyrosequencing and qPCR, we then benchmarked short and long-reads NGS technologies (Ion Torrent, Illumina, Oxford Nanopore Technologies) to sequence the complete cytb with a view to detecting and assessing the proportion of resistant variants of P. viticola at the scale of a field population. Eighteen populations collected from French vineyard fields in 2020 were analysed: 12 showed a variable proportion of G143A, 11 of E203-DE-V204 and 7 populations of the S34L variant that confers resistance to ametoctradin. Interestingly, the long reads were able to identify variants, including SNPs, with confidence and to detect a small proportion of P. viticola with multiple variants along the same cytb sequence. Overall, NGS appears to be a promising method for assessing fungicide resistance of pathogens linked to cytb modifications at the field population level. This approach could rapidly become a robust decision support tool for resistance management in the future.
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Affiliation(s)
| | - Benjamin Gillet
- Institut de Génomique Fonctionnelle de Lyon (IGFL), CNRS UMR 5242, Ecole Normale Supérieure de Lyon, INRAE USC 1370, Université Claude Bernard Lyon 1, Lyon, France
| | - Julien Dellinger
- Institut de Génomique Fonctionnelle de Lyon (IGFL), CNRS UMR 5242, Ecole Normale Supérieure de Lyon, INRAE USC 1370, Université Claude Bernard Lyon 1, Lyon, France
| | - Lalie Bellaton
- Institut de Génomique Fonctionnelle de Lyon (IGFL), CNRS UMR 5242, Ecole Normale Supérieure de Lyon, INRAE USC 1370, Université Claude Bernard Lyon 1, Lyon, France
| | - Pascale Roux
- Institut de Génomique Fonctionnelle de Lyon (IGFL), CNRS UMR 5242, Ecole Normale Supérieure de Lyon, INRAE USC 1370, Université Claude Bernard Lyon 1, Lyon, France
| | | | | | | | | | - Sandrine Hughes
- Institut de Génomique Fonctionnelle de Lyon (IGFL), CNRS UMR 5242, Ecole Normale Supérieure de Lyon, INRAE USC 1370, Université Claude Bernard Lyon 1, Lyon, France
- * E-mail: (SH); (SC)
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Standish JR, Góngora-Castillo E, Bowman MJ, Childs KL, Tian M, Quesada-Ocampo LM. Development, Validation, and Utility of Species-Specific Diagnostic Markers for Detection of Peronospora belbahrii. PHYTOPATHOLOGY 2022; 112:1667-1675. [PMID: 35196067 DOI: 10.1094/phyto-09-21-0393-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Peronospora belbahrii is an oomycete and the cause of basil downy mildew, one of the most destructive diseases affecting basil production worldwide. Disease management is challenging due to wind-dispersed sporangia and contaminated seed; therefore, identifying P. belbahrii in seed lots before sale or planting or in the field before symptoms develop could allow for timely deployment of disease management strategies. In this study, a draft genome assembly and next-generation sequencing reads for P. belbahrii, as well as publicly available DNA-seq and RNA-seq reads of several other downy mildew pathogens, were incorporated into a bioinformatics pipeline to predict P. belbahrii-specific diagnostic markers. The specificity of each candidate marker was validated against a diverse DNA collection of P. belbahrii, host tissue, and related oomycetes using PCR. Two species-specific markers were identified and used as templates to develop a highly sensitive probe-based real-time quantitative PCR (qPCR) assay that could detect P. belbahrii in leaf tissue and seed samples. Both markers were capable of reliably detecting as low as 500 fg/µl of P. belbahrii genomic DNA and as few as 10 sporangia. The qPCR assay was then validated with seed samples collected from a basil cultivar experiment. In total, 48 seed samples were collected and tested; P. belbahrii was detected in samples of all cultivars at estimated concentrations of 600 fg/µl up to 250 pg/µl and at as few as 10 sporangia up to >1,000 sporangia. The markers and assays are valuable for diagnostics and identifying P. belbahrii-contaminated seed lots to mitigate the effects of future basil downy mildew epidemics.
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Affiliation(s)
- J R Standish
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695-7613, U.S.A
| | - E Góngora-Castillo
- Department of Biotechnology, Yucatan Center for Scientific Research, Chuburná de Hidalgo, 97205 Mérida, Yucatán, México
| | - M J Bowman
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, U.S.A
- Ball Horticultural Company, West Chicago, IL 60185, U.S.A
| | - K L Childs
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, U.S.A
| | - M Tian
- Department of Plant and Environmental Protection Sciences, University of Hawaii at Manoa, Honolulu, HI 96822, U.S.A
| | - L M Quesada-Ocampo
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695-7613, U.S.A
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Salgado-Salazar C, Thines M. Two new species of Plasmopara affecting wild grapes in the USA. Mycol Prog 2022. [DOI: 10.1007/s11557-022-01813-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Biological Control of the Cucumber Downy Mildew Pathogen Pseudoperonospora cubensis. HORTICULTURAE 2022. [DOI: 10.3390/horticulturae8050410] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cucumber downy mildew (CDM) is a destructive plant disease caused by the air-borne oomycete pathogen Pseudoperonospora cubensis. CDM causes severe yield reduction of cucumber and significant economic losses. Biocontrol is a promising method to control CDM with the advantage of being beneficial to sustainable agricultural development. However, until now, no reviews of biocontrol of CDM have been reported. The objective of this review is to more comprehensively understand the biocontrol of CDM. In this review, the biological characteristics of P. cubensis are introduced, and strategies for screening biocontrol agents to suppress CDM are recommended. Then the current biocontrol agents, including fungi such as Trichoderma and biocontrol bacteria such as Bacillus, which possess the ability to control CDM, and their control characteristics and ability against CDM are also summarized. The potential mechanisms by which these biocontrol agents prevent CDM are discussed. Finally, several suggestions for future research on the biocontrol of CDM are provided.
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