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Arnold CJ, (Meyers) Hahn EA, Whetten R, Chartrain L, Cheema J, Brown JKM, Cowger C. Multiple routes to fungicide resistance: Interaction of Cyp51 gene sequences, copy number and expression. MOLECULAR PLANT PATHOLOGY 2024; 25:e13498. [PMID: 39305021 PMCID: PMC11415427 DOI: 10.1111/mpp.13498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 06/28/2024] [Accepted: 07/01/2024] [Indexed: 10/01/2024]
Abstract
We examined the molecular basis of triazole resistance in Blumeria graminis f. sp. tritici (wheat mildew, Bgt), a model organism among powdery mildews. Four genetic models for responses to triazole fungicides were identified among US and UK isolates, involving multiple genetic mechanisms. Firstly, only two amino acid substitutions in CYP51B lanosterol demethylase, the target of triazoles, were associated with resistance, Y136F and S509T (homologous to Y137F and S524T in the reference fungus Zymoseptoria tritici). As sequence variation did not explain the wide range of resistance, we also investigated Cyp51B copy number and expression, the latter using both reverse transcription-quantitative PCR and RNA-seq. The second model for resistance involved higher copy number and expression in isolates with a resistance allele; thirdly, however, moderate resistance was associated with higher copy number of wild-type Cyp51B in some US isolates. A fourth mechanism was heteroallelism with multiple alleles of Cyp51B. UK isolates, with significantly higher mean resistance than their US counterparts, had higher mean copy number, a high frequency of the S509T substitution, which was absent from the United States, and in the most resistant isolates, heteroallelism involving both sensitivity residues Y136+S509 and resistance residues F136+T509. Some US isolates were heteroallelic for Y136+S509 and F136+S509, but this was not associated with higher resistance. The obligate biotrophy of Bgt may constrain the tertiary structure and thus the sequence of CYP51B, so other variation that increases resistance may have a selective advantage. We describe a process by which heteroallelism may be adaptive when Bgt is intermittently exposed to triazoles.
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Affiliation(s)
- Corinne J. Arnold
- John Innes Centre, Norwich Research ParkNorwichUK
- Present address:
Camena Bioscience, Chesterford Research ParkCambridgeUK
| | - Emily A. (Meyers) Hahn
- Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth CarolinaUSA
- Present address:
Wisconsin Crop Innovation CenterUniversity of Wisconsin8520 University GreenMiddletonWisconsinUSA
| | - Rebecca Whetten
- United States Department of Agriculture‐Agricultural Research Service, Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth CarolinaUSA
| | | | | | | | - Christina Cowger
- United States Department of Agriculture‐Agricultural Research Service, Department of Entomology and Plant PathologyNorth Carolina State UniversityRaleighNorth CarolinaUSA
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Leconte A, Jacquin J, Duban M, Deweer C, Trapet P, Laruelle F, Farce A, Compère P, Sahmer K, Fiévet V, Hoste A, Siah A, Lounès-Hadj Sahraoui A, Jacques P, Coutte F, Deleu M, Muchembled J. Deciphering the mechanisms involved in reduced sensitivity to azoles and fengycin lipopeptide in Venturia inaequalis. Microbiol Res 2024; 286:127816. [PMID: 38964072 DOI: 10.1016/j.micres.2024.127816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 06/06/2024] [Accepted: 06/20/2024] [Indexed: 07/06/2024]
Abstract
Apple scab, caused by the hemibiotrophic fungus Venturia inaequalis, is currently the most common and damaging disease in apple orchards. Two strains of V. inaequalis (S755 and Rs552) with different sensitivities to azole fungicides and the bacterial metabolite fengycin were compared to determine the mechanisms responsible for these differences. Antifungal activity tests showed that Rs552 had reduced sensitivity to tebuconazole and tetraconazole, as well as to fengycin alone or in a binary mixture with other lipopeptides (iturin A, pumilacidin, lichenysin). S755 was highly sensitive to fengycin, whose activity was close to that of tebuconazole. Unlike fengycin, lipopeptides from the iturin family (mycosubtilin, iturin A) had similar activity on both strains, while those from the surfactin family (lichenysin, pumilacidin) were not active, except in binary mixtures with fengycin. The activity of lipopeptides varies according to their family and structure. Analyses to determine the difference in sensitivity to azoles (which target the CYP51 enzyme involved in the ergosterol biosynthesis pathway) showed that the reduced sensitivity in Rs552 is linked to (i) a constitutive increased expression of the Cyp51A gene caused by insertions in the upstream region and (ii) greater efflux by membrane pumps with the involvement of ABC transporters. Microscopic observations revealed that fengycin, known to interact with plasma membranes, induced morphological and cytological changes in cells from both strains. Sterol and phospholipid analyses showed a higher level of ergosta-7,22-dien-3-ol and a lower level of PI(C16:0/C18:1) in Rs552 compared with S755. These differences could therefore influence the composition of the plasma membrane and explain the differential sensitivity of the strains to fengycin. However, the similar antifungal activities of mycosubtilin and iturin A in the two strains indirectly indicate that sterols are probably not involved in the fengycin resistance mechanism. This leads to the conclusion that different mechanisms are responsible for the difference in susceptibility to azoles or fengycin in the strains studied.
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Affiliation(s)
- Aline Leconte
- JUNIA, UMRt BioEcoAgro 1158-INRAE, Plant Secondary Metabolites Team, Charles Viollette Institute, Lille F-59000, France; University of Lille, UMRt BioEcoAgro 1158-INRAE, Microbial Secondary Metabolites team, Charles Viollette Institute, Lille F-59000, France; University of Liège, UMRt BioEcoAgro 1158-INRAE, Microbial Secondary Metabolites team, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, Gembloux B-5030, Belgium
| | - Justine Jacquin
- JUNIA, UMRt BioEcoAgro 1158-INRAE, Plant Secondary Metabolites Team, Charles Viollette Institute, Lille F-59000, France
| | - Matthieu Duban
- University of Lille, UMRt BioEcoAgro 1158-INRAE, Microbial Secondary Metabolites team, Charles Viollette Institute, Lille F-59000, France
| | - Caroline Deweer
- JUNIA, UMRt BioEcoAgro 1158-INRAE, Plant Secondary Metabolites Team, Charles Viollette Institute, Lille F-59000, France
| | - Pauline Trapet
- JUNIA, UMRt BioEcoAgro 1158-INRAE, Plant Secondary Metabolites Team, Charles Viollette Institute, Lille F-59000, France
| | - Frédéric Laruelle
- Unité de Chimie Environnementale et Interactions sur le Vivant (EA 4492), Université Littoral Côte d'Opale, CEDEX CS 80699, Calais 62228, France
| | - Amaury Farce
- Université Lille, Inserm, CHU Lille, U1286 - INFINITE - Institut de recherche translationnelle sur l'inflammation, Lille F-59000, France
| | - Philippe Compère
- Laboratoire de morphologie fonctionnelle et évolutive, UR FOCUS, and Centre de recherche appliquée et d'enseignement en microscopie (CAREM), Université de Liège, Liège, Belgium
| | - Karin Sahmer
- Université Lille, IMT Lille Douai, Univ. Artois, JUNIA, ULR 4515 - LGCgE, Laboratoire de Génie Civil et geo-Environnement, Lille F-59000, France
| | - Valentin Fiévet
- JUNIA, UMRt BioEcoAgro 1158-INRAE, Plant Secondary Metabolites Team, Charles Viollette Institute, Lille F-59000, France
| | - Alexis Hoste
- University of Liège, UMRt BioEcoAgro 1158-INRAE, Microbial Secondary Metabolites team, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, Gembloux B-5030, Belgium
| | - Ali Siah
- JUNIA, UMRt BioEcoAgro 1158-INRAE, Plant Secondary Metabolites Team, Charles Viollette Institute, Lille F-59000, France
| | - Anissa Lounès-Hadj Sahraoui
- Unité de Chimie Environnementale et Interactions sur le Vivant (EA 4492), Université Littoral Côte d'Opale, CEDEX CS 80699, Calais 62228, France
| | - Philippe Jacques
- University of Liège, UMRt BioEcoAgro 1158-INRAE, Microbial Secondary Metabolites team, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, Gembloux B-5030, Belgium
| | - François Coutte
- University of Lille, UMRt BioEcoAgro 1158-INRAE, Microbial Secondary Metabolites team, Charles Viollette Institute, Lille F-59000, France
| | - Magali Deleu
- University of Liège, UMRt BioEcoAgro 1158-INRAE, Microbial Secondary Metabolites team, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, Gembloux B-5030, Belgium
| | - Jérôme Muchembled
- JUNIA, UMRt BioEcoAgro 1158-INRAE, Plant Secondary Metabolites Team, Charles Viollette Institute, Lille F-59000, France.
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Li G, Zhang L, Li Y, Li X, Gao X, Dai T, Miao J, Liu X. Analysis of resistance risk and mechanism of the 14α-demethylation inhibitor ipconazole in Fusarium pseudograminearum. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2024; 199:105786. [PMID: 38458686 DOI: 10.1016/j.pestbp.2024.105786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/07/2024] [Accepted: 01/09/2024] [Indexed: 03/10/2024]
Abstract
Ipconazole is a broad-spectrum triazole fungicide that is highly effective against Fusarium pseudograminearum. However, its risk of developing resistance and mechanism are not well understood in F. pseudograminearum. Here, the sensitivities of 101 F. pseudograminearum isolates to ipconazole were investigated, and the average EC50 value was 0.1072 μg/mL. Seven mutants resistant to ipconazole were obtained by fungicide adaption, with all but one showing reduced fitness relative to the parental isolates. Cross-resistance was found between ipconazole and mefentrifluconazole and tebuconazole, but none between ipconazole and pydiflumetofen, carbendazim, fludioxonil, or phenamacril. In summary, these findings suggest that there is a low risk of F. pseudograminearum developing resistance to ipconazole. Additionally, a point mutation, G464S, was seen in FpCYP51B and overexpression of FpCYP51A, FpCYP51B and FpCYP51C was observed in ipconazole-resistant mutants. Assays, including transformation and molecular docking, indicated that G464S conferred ipconazole resistance in F. pseudograminearum.
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Affiliation(s)
- Guixiang Li
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Ling Zhang
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Yiwen Li
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Xiong Li
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Xuheng Gao
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Tan Dai
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Jianqiang Miao
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China.
| | - Xili Liu
- State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China; Department of Plant Pathology, College of Plant Protection, China Agricultural University, 2 Yuanmingyuanxi Road, Beijing 100193, China.
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Heaven T, Armitage AD, Xu X, Goddard MR, Cockerton HM. Dose-Dependent Genetic Resistance to Azole Fungicides Found in the Apple Scab Pathogen. J Fungi (Basel) 2023; 9:1136. [PMID: 38132737 PMCID: PMC10744243 DOI: 10.3390/jof9121136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/13/2023] [Accepted: 11/17/2023] [Indexed: 12/23/2023] Open
Abstract
The evolution of azole resistance in fungal pathogens presents a major challenge in both crop production and human health. Apple orchards across the world are faced with the emergence of azole fungicide resistance in the apple scab pathogen Venturia inaequalis. Target site point mutations observed in this fungus to date cannot fully explain the reduction in sensitivity to azole fungicides. Here, polygenic resistance to tebuconazole was studied across a population of V. inaequalis. Genotyping by sequencing allowed Quantitative Trait Loci (QTLs) mapping to identify the genetic components controlling this fungicide resistance. Dose-dependent genetic resistance was identified, with distinct genetic components contributing to fungicide resistance at different exposure levels. A QTL within linkage group seven explained 65% of the variation in the effective dose required to reduce growth by 50% (ED50). This locus was also involved in resistance at lower fungicide doses (ED10). A second QTL in linkage group one was associated with dose-dependent resistance, explaining 34% of variation at low fungicide doses (ED10), but did not contribute to resistance at higher doses (ED50 and ED90). Within QTL regions, non-synonymous mutations were observed in several ATP-Binding Cassette and Major Facilitator SuperFamily transporter genes. These findings provide insight into the mechanisms of fungicide resistance that have evolved in horticultural pathogens. Identification of resistance gene candidates supports the development of molecular diagnostics to inform management practices.
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Affiliation(s)
- Thomas Heaven
- National Institute of Agricultural Botany, New Road, East Malling, West Malling, Kent ME19 6BJ, UK;
- The School of Life and Environmental Sciences, University of Lincoln, Lincoln LN6 7DL, UK;
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | | | - Xiangming Xu
- National Institute of Agricultural Botany, New Road, East Malling, West Malling, Kent ME19 6BJ, UK;
| | - Matthew R. Goddard
- The School of Life and Environmental Sciences, University of Lincoln, Lincoln LN6 7DL, UK;
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Liu Y, Song C, Ren X, Wu G, Ma Z, Zhao M, Xie Y, Li Y, Lai Y. Screening for Fungicide Efficacy in Controlling Blackleg Disease in Wasabi ( Eutrema japonicum). PLANTS (BASEL, SWITZERLAND) 2023; 12:3149. [PMID: 37687395 PMCID: PMC10490250 DOI: 10.3390/plants12173149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 08/06/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023]
Abstract
Blackleg disease is devastating for wasabi (Eutrema japonicum) production, occurring at any time and everywhere within the main production area of the Sichuan Province, China. There have been very few studies on the chemical control of this disease. In this study, we isolated and identified a local popular strain of the pathogen Plenodomus wasabiae. The isolated fungus strain caused typical disease spots on the leaves and rhizomes upon inoculation back to wasabi seedlings. The symptoms of blackleg disease developed very quickly, becaming visible on the second day after exposure to P. wasabiae and leading to death within one week. We then evaluated the efficacy of ten widely used fungicides to screen out effective fungicides. The efficacy of the tested fungicides was determined through mycelial growth inhibition on medium plates. As a result, tebuconazole and pyraclostrobin were able to inhibit the mycelial growth of P. wasabiae, and the most widely used dimethomorph in local production areas produced the lowest inhibition activity (13.8%). Nevertheless, the highest control efficacy of tebuconazole and pyraclostrobin on wasabi seedlings was only 47.48% and 39.03%, respectively. Generally, the control efficacy of spraying the fungicide before inoculation was better than that after inoculation. An increase in the application concentration of the two fungicides did not proportionately result in improved performance. We cloned the full-length sequence of sterol 14-demethylase (CYP51) and cytochrome B (CYTB) of which the mutations may contribute to the possible antifungalresistance. These two genes of the isolated fungus do not possess any reported mutations that lead to fungicide resistance. Previous studies indicate that there is a significant difference between fungicides in terms of the effectiveness of controlling blackleg disease; however, the control efficacy of fungicides is limited in blackleg control. Therefore, field management to prevent wound infection and unfavorable environmental conditions are more important than pesticide management.
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Affiliation(s)
- Yanjun Liu
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China; (Y.L.); (C.S.); (Z.M.); (M.Z.); (Y.X.); (Y.L.)
| | - Changjiang Song
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China; (Y.L.); (C.S.); (Z.M.); (M.Z.); (Y.X.); (Y.L.)
| | - Xin Ren
- Guangyuan Xifu Biotechnology Company, Guangyuan 628000, China;
| | - Guoli Wu
- Jiaxing Agricultural and Fishery Technology Promotion Station, Jiaxing 314000, China;
| | - Zihan Ma
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China; (Y.L.); (C.S.); (Z.M.); (M.Z.); (Y.X.); (Y.L.)
| | - Mantong Zhao
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China; (Y.L.); (C.S.); (Z.M.); (M.Z.); (Y.X.); (Y.L.)
| | - Yujia Xie
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China; (Y.L.); (C.S.); (Z.M.); (M.Z.); (Y.X.); (Y.L.)
| | - Yu Li
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China; (Y.L.); (C.S.); (Z.M.); (M.Z.); (Y.X.); (Y.L.)
| | - Yunsong Lai
- College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China; (Y.L.); (C.S.); (Z.M.); (M.Z.); (Y.X.); (Y.L.)
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Strickland DA, Spychalla JP, van Zoeren JE, Basedow MR, Donahue DJ, Cox KD. Assessment of Fungicide Resistance via Molecular Assay in Populations of Podosphaera leucotricha, Causal Agent of Apple Powdery Mildew, in New York. PLANT DISEASE 2023; 107:2606-2612. [PMID: 36802297 DOI: 10.1094/pdis-12-22-2820-sr] [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: 06/18/2023]
Abstract
Podosphaera leucotricha, causal agent of apple powdery mildew, is a pathogen endemic worldwide where apples are produced. In the absence of durable host resistance, the disease is most effectively managed in conventional orchards with single-site fungicides. In New York State, increasingly erratic precipitation patterns and warmer temperatures due to climate change may create a regional environment more conducive to apple powdery mildew development and spread. In this scenario, outbreaks of apple powdery mildew may supplant the apple diseases of current management concern: apple scab and fire blight. Presently, there have been no reports from producers of fungicide control failures for apple powdery mildew, though increased disease incidence has been reported to and observed by the authors. As such, action was needed to assess the fungicide resistance status of populations of P. leucotricha to ensure key classes of single-site fungicides (FRAC 3, demethylation inhibitors, DMI; FRAC 11, quinone outside inhibitors, QoI; and FRAC 7, succinate dehydrogenase inhibitors, SDHI) remain effective. In a 2-year survey (2021 to 2022), we collected 160 samples of P. leucotricha from 43 orchards, representing conventional, organic, low-input, and unmanaged orchards from New York's primary production regions. Samples were screened for mutations in the target genes (CYP51, cytb, and sdhB) historically known to confer fungicide resistance in other fungal pathogens to the DMI, QoI, and SDHI fungicide classes, respectively. Across all samples, no nucleotide sequence mutations that translated into problematic amino acid substitutions were found in the target genes, suggesting that New York populations of P. leucotricha remain sensitive to the DMI, QoI, and SDHI fungicide classes, provided no other fungicide resistance mechanism is at play in the population.
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Affiliation(s)
- David A Strickland
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Jamie P Spychalla
- Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, State College, PA 16802
| | - Janet E van Zoeren
- Lake Ontario Fruit Program, Cornell Cooperative Extension, Cornell University, Albion, NY 14411
| | - Michael R Basedow
- Eastern New York Commercial Horticulture Program, Cornell Cooperative Extension, Cornell University, Plattsburgh, NY 12901
| | - Daniel J Donahue
- Eastern New York Commercial Horticulture Program, Cornell Cooperative Extension, Cornell University, Highland, NY 12528
| | - Kerik D Cox
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
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Gorshkov AP, Kusakin PG, Borisov YG, Tsyganova AV, Tsyganov VE. Effect of Triazole Fungicides Titul Duo and Vintage on the Development of Pea ( Pisum sativum L.) Symbiotic Nodules. Int J Mol Sci 2023; 24:8646. [PMID: 37240010 PMCID: PMC10217885 DOI: 10.3390/ijms24108646] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 05/05/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
Triazole fungicides are widely used in agricultural production for plant protection, including pea (Pisum sativum L.). The use of fungicides can negatively affect the legume-Rhizobium symbiosis. In this study, the effects of triazole fungicides Vintage and Titul Duo on nodule formation and, in particular, on nodule morphology, were studied. Both fungicides at the highest concentration decreased the nodule number and dry weight of the roots 20 days after inoculation. Transmission electron microscopy revealed the following ultrastructural changes in nodules: modifications in the cell walls (their clearing and thinning), thickening of the infection thread walls with the formation of outgrowths, accumulation of poly-β-hydroxybutyrates in bacteroids, expansion of the peribacteroid space, and fusion of symbiosomes. Fungicides Vintage and Titul Duo negatively affect the composition of cell walls, leading to a decrease in the activity of synthesis of cellulose microfibrils and an increase in the number of matrix polysaccharides of cell walls. The results obtained coincide well with the data of transcriptomic analysis, which revealed an increase in the expression levels of genes that control cell wall modification and defense reactions. The data obtained indicate the need for further research on the effects of pesticides on the legume-Rhizobium symbiosis in order to optimize their use.
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Affiliation(s)
- Artemii P. Gorshkov
- Laboratory of Molecular and Cell Biology, All-Russia Research Institute for Agricultural Microbiology, Saint Petersburg 196608, Russia; (A.P.G.); (P.G.K.); (A.V.T.)
| | - Pyotr G. Kusakin
- Laboratory of Molecular and Cell Biology, All-Russia Research Institute for Agricultural Microbiology, Saint Petersburg 196608, Russia; (A.P.G.); (P.G.K.); (A.V.T.)
| | - Yaroslav G. Borisov
- Research Resource Centre “Molecular and Cell Technologies”, Saint Petersburg State University, Saint Petersburg 199034, Russia;
| | - Anna V. Tsyganova
- Laboratory of Molecular and Cell Biology, All-Russia Research Institute for Agricultural Microbiology, Saint Petersburg 196608, Russia; (A.P.G.); (P.G.K.); (A.V.T.)
| | - Viktor E. Tsyganov
- Laboratory of Molecular and Cell Biology, All-Russia Research Institute for Agricultural Microbiology, Saint Petersburg 196608, Russia; (A.P.G.); (P.G.K.); (A.V.T.)
- Saint Petersburg Scientific Center RAS, Universitetskaya Embankment 5, Saint Petersburg 199034, Russia
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8
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Yang G, Cui S, Ma N, Song Y, Ma J, Huang W, Zhang Y, Xu J. Genetic Structure and Triazole Antifungal Susceptibilities of Alternaria alternata from Greenhouses in Kunming, China. Microbiol Spectr 2022; 10:e0038222. [PMID: 35546576 PMCID: PMC9241833 DOI: 10.1128/spectrum.00382-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 04/22/2022] [Indexed: 11/20/2022] Open
Abstract
Alternaria alternata is an opportunistic human fungal pathogen and a ubiquitous phytopathogen capable of causing diseases to >100 agricultural crops and ornamental plants. To control plant diseases caused by A. alternata, triazole fungicides have been widely used both in open crop and vegetable fields and in indoor growth facilities such as greenhouses. At present, the effect of fungicide use on triazole resistance development in A. alternata populations is not known. Here, we isolated 237 A. alternata strains from nine greenhouses around metropolitan Kunming in Yunnan, southwest China, determined their genotypes using 10 short tandem repeat markers, and quantified their susceptibility to four triazoles (difenoconazole, tebuconazole, itraconazole, and voriconazole). Abundant allelic and genotypic diversities were detected among these A. alternata strains. Significantly, over 17% of the strains were resistant to difenoconazole, and both known and new drug-resistance mutations were found in the triazole target gene cyp51. Our findings of high-level genetic variation of A. alternata in greenhouses coupled with high-frequency fungicide resistance call for greater attention to continued monitoring and to developing alternative plant fungal disease management strategies in greenhouses. IMPORTANCE Alternaria alternata is among the most common fungi in our environments, such as indoor facilities, the soil, and outdoor air. It can cause diseases in >100 crop and ornamental plants. Furthermore, it can cause human infections. However, our understanding of its genetic diversity and antifungal susceptibility is very limited. Indeed, the critical threshold values for resistance have not been defined for most antifungal drugs in this species. Greenhouses are known to have heavy applications of agricultural fungicides. In this study, we analyzed strains of A. alternata from nine greenhouses near metropolitan Kunming in southwestern China. Our study revealed very high genetic diversity and identified strains with high MIC values against two agricultural and two medical triazole antifungals within each of the nine greenhouses. Our study calls for greater attention to this emerging threat to food security and human health.
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Affiliation(s)
- Guangzhu Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, Yunnan University, Kunming, People’s Republic of China
- School of Life Science, Yunnan University, Kunming, People’s Republic of China
- Horticultural Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, People’s Republic of China
| | - Sai Cui
- School of Life Science, Yunnan University, Kunming, People’s Republic of China
| | - Nan Ma
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, Yunnan University, Kunming, People’s Republic of China
| | - Yuansha Song
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, Yunnan University, Kunming, People’s Republic of China
| | - Jun Ma
- Horticultural Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, People’s Republic of China
| | - Wenjing Huang
- Horticultural Research Institute, Yunnan Academy of Agricultural Sciences, Kunming, People’s Republic of China
| | - Ying Zhang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, Yunnan University, Kunming, People’s Republic of China
| | - Jianping Xu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Key Laboratory for Southwest Microbial Diversity of the Ministry of Education, Yunnan University, Kunming, People’s Republic of China
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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9
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Strickland DA, Villani SM, Cox KD. Optimizing Use of DMI Fungicides for Management of Apple Powdery Mildew Caused by Podosphaera leucotricha in New York State. PLANT DISEASE 2022; 106:1226-1237. [PMID: 34854765 DOI: 10.1094/pdis-09-21-2025-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Powdery mildew, caused by the ascomycete Podosphaera leucotricha, is an endemic disease found wherever apples are grown that reduces both tree vigor and fresh market yield. In the absence of durable host resistance, chemical management is the primary means of disease control. Demethylation inhibitor (DMI) fungicides are widely used to manage apple powdery mildew, but members within this fungicide class have been observed to differ in efficacy with respect to disease control. Moreover, debate exists as to the optimal timing of DMI fungicide applications for management of apple powdery mildew. In this regard, the goal of this study was to determine the best-use practices for DMI fungicides to manage apple powdery mildew in New York State. Multiyear trials were conducted to evaluate the potential differential efficacy performance of four common DMI fungicides, and additional trials were conducted to assess optimal application timing. In all years, we observed that treatments of flutriafol and myclobutanil consistently had the lowest incidences of powdery mildew compared with difenoconazole and fenbuconazole. In the 2018 and 2021 trials, the newly registered mefentrifluconazole was more comparable to the difenoconazole program with respect to powdery mildew disease incidence. We hypothesize that differences in DMI efficacy may result from each fungicide's water solubility and lipophilicity characteristics and thus their ability to move systemically in the host or more easily penetrate the surface of germinating conidia. Applications timed between petal fall and first cover resulted in the lowest incidence of powdery mildew on terminal leaves of apple shoots compared with applications timed before petal fall. These observations are contrary to previous studies conducted in regions with differing climates. We also found that the incidence of secondary powdery mildew observed 2 weeks after petal fall was influenced by applications of DMI fungicides during the previous season. For example, management programs consisting of applications of flutriafol or myclobutanil in the previous season tended to have lower incidence of apple powdery in the next spring, presumably because of reductions in overwintering inoculum. Despite reports of DMI resistance in other apple pathosystems, the DMI fungicide class is still relevant for the successful management of apple powdery mildew in New York State.
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Affiliation(s)
- David A Strickland
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Geneva, NY 14456
| | - Sara M Villani
- Department of Entomology and Plant Pathology, Mountain Horticulture and Crops Research & Extension Center, North Carolina State University, Mills River, NC 28759
| | - Kerik D Cox
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Geneva, NY 14456
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10
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Zhao Y, Sun H, Li J, Ju C, Huang J. The Transcription Factor FgAtrR Regulates Asexual and Sexual Development, Virulence, and DON Production and Contributes to Intrinsic Resistance to Azole Fungicides in Fusarium graminearum. BIOLOGY 2022; 11:biology11020326. [PMID: 35205191 PMCID: PMC8869466 DOI: 10.3390/biology11020326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 02/14/2022] [Indexed: 12/22/2022]
Abstract
Simple Summary Fusarium graminearum is a devastating plant pathogen that can cause wheat head blight. Azole fungicides are commonly used chemicals for control of this disease. However, F. graminearum strains resistant to these fungicides have emerged. To better understand the azole resistance mechanism of F. graminearum, we identified and characterized the Zn(II)2-Cys6 transcription factor FgAtrR in F. graminearum. We found that FgAtrR played critical roles in vegetative growth, conidia production, perithecium formation, and virulence on wheat heads and corn silks. FgAtrR was also involved in the resistance to azole antifungals by regulating the expression of the drug target FgCYP51s and efflux pump transporters. These results broadened our understanding of the azole resistance mechanisms of F. graminearum. Abstract Fusarium graminearum is the predominant causal agent of cereal Fusarium head blight disease (FHB) worldwide. The application of chemical fungicides such as azole antifungals is still the primary method for FHB control. However, to date, our knowledge of transcriptional regulation in the azole resistance of F. graminearum is quite limited. In this study, we identified and functionally characterized a Zn(II)2-Cys6 transcription factor FgAtrR in F. graminearum. We constructed a FgAtrR deletion mutant and found that deletion of FgAtrR resulted in faster radial growth with serious pigmentation defects, significantly reduced conidial production, and an inability to form perithecia. The pathogenicity of the ΔFgAtrR mutant on wheat spikes and corn silks was severely impaired with reduced deoxynivalenol production, while the tolerance to prochloraz and propiconazole of the deletion mutant was also significantly decreased. RNA-seq indicated that many metabolic pathways were affected by the deletion of FgAtrR. Importantly, FgAtrR could regulate the expression of the FgCYP51A and ABC transporters, which are the main contributors to azole resistance. These results demonstrated that FgAtrR played essential roles in asexual and sexual development, DON production, and pathogenicity, and contributed to intrinsic resistance to azole fungicides in F. graminearum. This study will help us improve the understanding of the azole resistance mechanism in F. graminearum.
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11
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Zhao H, Tao X, Song W, Xu H, Li M, Cai Y, Wang J, Duan Y, Zhou M. Mechanism of Fusarium graminearum Resistance to Ergosterol Biosynthesis Inhibitors: G443S Substitution of the Drug Target FgCYP51A. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:1788-1798. [PMID: 35129347 DOI: 10.1021/acs.jafc.1c07543] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Fusarium head blight (FHB), caused by the Fusarium graminearum species complex, is a devastating fungal disease resulting in substantial yield and quality losses. Ergosterol biosynthesis inhibitors (EBIs) are the most popular chemicals for controlling FHB. Recently, the resistance of F. graminearum to EBIs has emerged in the field, and an amino acid substitution (G443S) of the sterol 14α-demethylase FgCYP51A was detected in the field resistant strains. To further illustrate the resistance mechanism of F. graminearum to EBIs, site-directed mutants conferring the G443S substitution of FgCYP51A were generated from the progenitor strain PH-1 via genetic transformation with site-directed mutagenesis. We found that the FgCYP51A-G443S substitution significantly decreased the sensitivity of F. graminearum to EBIs with EC50 values ranging from 0.1190 to 0.2302 μg mL-1 and EC90 values ranging from 1.3420 to 9.1119 μg mL-1 for tebuconazole. Furthermore, the FgCYP51A-G443S substitution decreased sexual reproduction and virulence, which will reduce the initial infection source of pathogen populations in the field, while the increase of sporulation capability may enhance the frequencies of the disease cycle, thereby contributing to epidemics of FHB disease. Surprisingly, the FgCYP51A-G443S substitution accelerated DON biosynthesis by upregulating TRI5 expression and enhancing the fluorescence intensity of TRI1-GFP, the marker protein of Fusarium toxisomes. Thus, we concluded that the FgCYP51A-G443S substitution regulates EBI-fungicide resistance and DON biosynthesis, increasing the risk of fungicide resistance development in the field, thereby threatening the control efficacy of EBIs against FHB.
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Affiliation(s)
- Huahua Zhao
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Xian Tao
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Wen Song
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Haorong Xu
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Meixia Li
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Yiqiang Cai
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
- State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
| | - Jianxin Wang
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
- State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
| | - Yabing Duan
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
- State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
| | - Mingguo Zhou
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
- State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
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12
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Moore LC, Brenneman TB, Waliullah S, Bock CH, Ali ME. Multiple Mutations and Overexpression in the CYP51A and B Genes Lead to Decreased Sensitivity of Venturia effusa to Tebuconazole. Curr Issues Mol Biol 2022; 44:670-685. [PMID: 35723332 PMCID: PMC8928975 DOI: 10.3390/cimb44020047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/21/2022] [Accepted: 01/24/2022] [Indexed: 11/16/2022] Open
Abstract
Multiple demethylation-inhibiting (DMI) fungicides are used to control pecan scab, caused by Venturia effusa. To compare the efficacy of various DMI fungicides on V. effusa, field trials were conducted at multiple locations applying fungicides to individual pecan terminals. In vitro assays were conducted to test the sensitivity of V. effusa isolates from multiple locations to various concentrations of tebuconazole. Both studies confirmed high levels of resistance to tebuconazole. To investigate the mechanism of resistance, two copies of the CYP51 gene, CYP51A and CYP51B, of resistant and sensitive isolates were sequenced and scanned for mutations. In the CYP51A gene, mutation at codon 444 (G444D), and in the CYP51B gene, mutations at codon 357 (G357H) and 177 (I77T/I77L) were found in resistant isolates. Expression analysis of CYP51A and CYP51B revealed enhanced expression in the resistant isolates compared to the sensitive isolates. There were 3.0- and 1.9-fold increases in gene expression in the resistant isolates compared to the sensitive isolates for the CYP51A and CYP51B genes, respectively. Therefore, two potential mechanisms—multiple point mutations and gene over expression in the CYP51 gene of V. effusa isolates—were revealed as likely reasons for the observed resistance in isolates of V. effusa to tebuconazole.
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Affiliation(s)
- Logan C. Moore
- Department of Plant Pathology, Coastal Plain Experiment Station, The University of Georgia, Tifton, GA 31793, USA; (L.C.M.); (T.B.B.); (S.W.)
| | - Timothy B. Brenneman
- Department of Plant Pathology, Coastal Plain Experiment Station, The University of Georgia, Tifton, GA 31793, USA; (L.C.M.); (T.B.B.); (S.W.)
| | - Sumyya Waliullah
- Department of Plant Pathology, Coastal Plain Experiment Station, The University of Georgia, Tifton, GA 31793, USA; (L.C.M.); (T.B.B.); (S.W.)
| | - Clive H. Bock
- United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Station, Byron, GA 31008, USA;
| | - Md Emran Ali
- Department of Plant Pathology, Coastal Plain Experiment Station, The University of Georgia, Tifton, GA 31793, USA; (L.C.M.); (T.B.B.); (S.W.)
- Correspondence:
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13
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Ayer KM, Strickland DA, Choi M, Cox KD. Optimizing the Integration of a Biopesticide ( Bacillus subtilis QST 713) with a Single-Site Fungicide (Benzovindiflupyr) to Reduce Reliance on Synthetic Multisite Fungicides (Captan and Mancozeb) for Management of Apple Scab. PLANT DISEASE 2021; 105:3545-3553. [PMID: 34142850 DOI: 10.1094/pdis-02-21-0426-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Apple scab is one of the most economically important diseases of apple in temperate production regions. In the absence of durable host resistance in commercially preferred cultivars, considerable applications of fungicides are needed to manage this disease. With the sequential development of resistance to nearly all classes of single-site fungicides in the apple scab pathogen Venturia inaequalis, synthetic multisite fungicides, such as mancozeb and captan, often comprise the core of chemical management programs for apple scab. Although these fungicides have demonstrable benefits for both disease and fungicide resistance management, the sustainability movement within agriculture aims to reduce reliance on such fungicides because of their broader environmental impacts. In this study, we establish a framework to enhance the feasibility of chemical management programs that do not rely on use of synthetic multisite protectant fungicides to manage apple scab. Specifically, we wish to evaluate chemical programs that integrate the biopesticide Bacillus subtilis QST 713 (Serenade Opti) in rotation with benzovindiflupyr (Aprovia), a single-site fungicide belonging to the class of succinate dehydrogenase inhibitors (SDHI), to circumvent the need for applications of synthetic multisite fungicides. During implementation of these programs, disease incidence data were taken at biweekly intervals. Regardless of the seasonal challenges presented in the 2 years of this study, when Bacillus subtilis QST 713 was used in place of captan and mancozeb mixtures, we did not observe any significant differences (P > 0.05) in development of apple scab symptoms between any of the management programs for the vertical axis or super spindle orchards in either year. This potential for substituting synthetic multisite fungicides with biopesticides is best realized when the programs are used with a decision support system in a super spindle planting system, where trees have reduced canopy densities. This 2-year study shows the potential to achieve adequate disease control using the integration of SDHI fungicides and biological controls without the use of synthetic multisite fungicides.
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Affiliation(s)
- K M Ayer
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - D A Strickland
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - M Choi
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - K D Cox
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
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14
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Spanner R, Taliadoros D, Richards J, Rivera-Varas V, Neubauer J, Natwick M, Hamilton O, Vaghefi N, Pethybridge S, Secor GA, Friesen TL, Stukenbrock EH, Bolton MD. Genome-Wide Association and Selective Sweep Studies Reveal the Complex Genetic Architecture of DMI Fungicide Resistance in Cercospora beticola. Genome Biol Evol 2021; 13:6367780. [PMID: 34499119 DOI: 10.1093/gbe/evab209] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/05/2021] [Indexed: 12/21/2022] Open
Abstract
The rapid and widespread evolution of fungicide resistance remains a challenge for crop disease management. The demethylation inhibitor (DMI) class of fungicides is a widely used chemistry for managing disease, but there has been a gradual decline in efficacy in many crop pathosystems. Reliance on DMI fungicides has increased resistance in populations of the plant pathogenic fungus Cercospora beticola worldwide. To better understand the genetic and evolutionary basis for DMI resistance in C. beticola, a genome-wide association study (GWAS) and selective sweep analysis were conducted for the first time in this species. We performed whole-genome resequencing of 190 C. beticola isolates infecting sugar beet (Beta vulgaris ssp. vulgaris). All isolates were phenotyped for sensitivity to the DMI tetraconazole. Intragenic markers on chromosomes 1, 4, and 9 were significantly associated with DMI fungicide resistance, including a polyketide synthase gene and the gene encoding the DMI target CbCYP51. Haplotype analysis of CbCYP51 identified a synonymous mutation (E170) and nonsynonymous mutations (L144F, I387M, and Y464S) associated with DMI resistance. Genome-wide scans of selection showed that several of the GWAS mutations for fungicide resistance resided in regions that have recently undergone a selective sweep. Using radial plate growth on selected media as a fitness proxy, we did not find a trade-off associated with DMI fungicide resistance. Taken together, we show that population genomic data from a crop pathogen can allow the identification of mutations conferring fungicide resistance and inform about their origins in the pathogen population.
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Affiliation(s)
- Rebecca Spanner
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA.,Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Demetris Taliadoros
- Environmental Genomics Group, Max Planck Institute for Evolutionary Biology, Plön, Germany.,Christian-Albrechts University of Kiel, Germany
| | - Jonathan Richards
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, USA
| | - Viviana Rivera-Varas
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Jonathan Neubauer
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA
| | - Mari Natwick
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA
| | - Olivia Hamilton
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Niloofar Vaghefi
- Centre for Crop Health, University of Southern Queensland, Toowoomba, Queensland, Australia
| | - Sarah Pethybridge
- School of Integrative Plant Science, Cornell University, Geneva, New York, USA
| | - Gary A Secor
- Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Timothy L Friesen
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA.,Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
| | - Eva H Stukenbrock
- Botanical Institute, Christian-Albrechts University of Kiel, Kiel, Germany.,Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Melvin D Bolton
- Northern Crop Science Laboratory, United States Department of Agriculture, Fargo, North Dakota, USA.,Department of Plant Pathology, North Dakota State University, Fargo, North Dakota, USA
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15
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Zhao Y, Chi M, Sun H, Qian H, Yang J, Huang J. The FgCYP51B Y123H Mutation Confers Reduced Sensitivity to Prochloraz and Is Important for Conidiation and Ascospore Development in Fusarium graminearum. PHYTOPATHOLOGY 2021; 111:1420-1427. [PMID: 33399013 DOI: 10.1094/phyto-09-20-0431-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Fusarium graminearum is one of the most important causal agents of Fusarium head blight disease and is controlled mainly by chemicals such as demethylation inhibitor (DMI) fungicides. FgCYP51B is one of the DMI targets in F. graminearum, and Tyrosine123 (Y123) is an important amino acid in F. graminearum CYP51B, located in one of predicted substrate binding pockets based on the binding mode between DMIs and CYP51B. Previous studies suggest that resistance to DMI fungicides is attributed primarily to point mutations in the CYP51 gene and that the Y123H mutation in F. verticillioides CYP51 confers prochloraz resistance in the laboratory. To investigate the function of FgCYP51B Y123 residue in the growth and development, pathogenicity, and DMI resistance, we generated and analyzed the FgCYP51B Y123H mutant. Results revealed that the Y123H mutation led to reduced conidial sporulation and affected ascospore development; moreover, the mutation conferred reduced sensitivity to prochloraz. Quantitative PCR and molecular docking were performed to investigate the resistance mechanism. Results indicated that Y123H mutation changed the target gene expression and decreased the binding affinity of FgCYP51 to prochloraz. These results will attract more attention to the potential DMI-resistant mutation of F. graminearum and increase our understanding of the DMI resistance mechanism.
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Affiliation(s)
- Yanxiang Zhao
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao 266109, China
| | - Mengyu Chi
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao 266109, China
| | - Hunlin Sun
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao 266109, China
| | - Hengwei Qian
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao 266109, China
| | - Jun Yang
- State Key Laboratory of Agrobiotechnology, and Ministry of Agriculture Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Jinguang Huang
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao 266109, China
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16
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Chong P, Essoh JN, Arango Isaza RE, Keizer P, Stergiopoulos I, Seidl MF, Guzman M, Sandoval J, Verweij PE, Scalliet G, Sierotzski H, de Lapeyre de Bellaire L, Crous PW, Carlier J, Cros S, Meijer HJG, Peralta EL, Kema GHJ. A world-wide analysis of reduced sensitivity to DMI fungicides in the banana pathogen Pseudocercospora fijiensis. PEST MANAGEMENT SCIENCE 2021; 77:3273-3288. [PMID: 33764651 PMCID: PMC8252799 DOI: 10.1002/ps.6372] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/19/2021] [Accepted: 03/25/2021] [Indexed: 05/25/2023]
Abstract
BACKGROUND Pseudocercospora fijiensis is the causal agent of the black leaf streak disease (BLSD) of banana. Bananas are important global export commodities and a major staple food. Their susceptibility to BLSD pushes disease management towards excessive fungicide use, largely relying on multisite inhibitors and sterol demethylation inhibitors (DMIs). These fungicides are ubiquitous in plant disease control, targeting the CYP51 enzyme. We examined sensitivity to DMIs in P. fijiensis field isolates collected from various major banana production zones in Colombia, Costa Rica, Dominican Republic, Ecuador, the Philippines, Guadalupe, Martinique and Cameroon and determined the underlying genetic reasons for the observed phenotypes. RESULTS We observed a continuous range of sensitivity towards the DMI fungicides difenoconazole, epoxiconazole and propiconazole with clear cross-sensitivity. Sequence analyses of PfCYP51 in 266 isolates showed 28 independent amino acid substitutions, nine of which correlated with reduced sensitivity to DMIs. In addition to the mutations, we observed up to six insertions in the Pfcyp51 promoter. Such promoter insertions contain repeated elements with a palindromic core and correlate with the enhanced expression of Pfcyp51 and hence with reduced DMI sensitivity. Wild-type isolates from unsprayed bananas fields did not contain any promoter insertions. CONCLUSION The presented data significantly contribute to understanding of the evolution and global distribution of DMI resistance mechanisms in P. fijiensis field populations and facilitate the prediction of different DMI efficacy. The overall reduced DMI sensitivity calls for the deployment of a wider range of solutions for sustainable control of this major banana disease. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Pablo Chong
- Centro de Investigaciones Biotecnológicas del Ecuador, CIBELaboratorio de FitopatologíaEscuela Superior Politécnica del Litoral, ESPOL.km 30.5 via perimetralGuayaquil090112Ecuador
- Wageningen ResearchWageningen University and ResearchWageningenThe Netherlands
| | - Josué Ngando Essoh
- Unité de Recherches sur les Systèmes de Production Durables (SYSPROD)Laboratoire de PhytopathologieCentre Africain de Recherches sur Bananiers et Plantain, CARBAPDoualaCameroun
- UPR GECOCIRADMontpellierFrance
| | - Rafael E Arango Isaza
- Escuela de BiocienciasUniversidad Nacional de Colombia, Sede Medellín (UNALMED)MedellínColombia
- Corporación para Investigaciones BiológicasUnidad de biotecnología Vegetal (CIB)MedellínColombia
| | - Paul Keizer
- BiometrisWageningen University and ResearchWageningenThe Netherlands
| | | | | | - Mauricio Guzman
- Departamento de FitoprotecciónCorporación Bananera Nacional (CORBANA S.A.)LimónCosta Rica
| | - Jorge Sandoval
- Departamento de FitoprotecciónCorporación Bananera Nacional (CORBANA S.A.)LimónCosta Rica
| | - Paul E Verweij
- Department of Medical MicrobiologyRadboud University Nijmegen Medical CenterNijmegenThe Netherlands
| | - Gabriel Scalliet
- Disease control groupSyngenta Crop Protection AGSteinSwitzerland
| | - Helge Sierotzski
- Disease control groupSyngenta Crop Protection AGSteinSwitzerland
| | | | - Pedro W Crous
- Hugo R. KruytgebouwUtrecht UniversityUtrechtThe Netherlands
- Lab of Evolutionary PhytopahtologyCBS‐KNAW Fungal Biodiversity CenterUtrechtThe Netherlands
| | - Jean Carlier
- UMR BGPICIRADMontpellierFrance
- BGPIMontpellier University, Cirad, Inrae, Montpellier SupAgroMontpellierFrance
| | - Sandrine Cros
- BGPIMontpellier University, Cirad, Inrae, Montpellier SupAgroMontpellierFrance
| | - Harold J G Meijer
- Wageningen ResearchWageningen University and ResearchWageningenThe Netherlands
| | - Esther Lilia Peralta
- Centro de Investigaciones Biotecnológicas del Ecuador, CIBELaboratorio de FitopatologíaEscuela Superior Politécnica del Litoral, ESPOL.km 30.5 via perimetralGuayaquil090112Ecuador
| | - Gert H J Kema
- Wageningen ResearchWageningen University and ResearchWageningenThe Netherlands
- Laboratory of PhytopathologyWageningen University and ResearchWageningenThe Netherlands
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17
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Ishii H, Cools HJ, Nishimura K, Borghi L, Kikuhara K, Yamaoka Y. DMI-Fungicide Resistance in Venturia nashicola, the Causal Agent of Asian Pear Scab-How Reliable Are Mycelial Growth Tests in Culture? Microorganisms 2021; 9:1377. [PMID: 34202715 PMCID: PMC8306131 DOI: 10.3390/microorganisms9071377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/19/2021] [Accepted: 06/21/2021] [Indexed: 11/16/2022] Open
Abstract
Scab, caused by Venturia nashicola, is among the most serious diseases of Asian pears and control of this disease largely relies on sterol demethylation inhibitor (DMI) fungicides. However, pear growers have complained about field performance of DMIs since the mid-2000s. In this study, to evaluate pathogen sensitivity, mycelial growth tests and inoculation tests were conducted using DMI-amended culture medium and fungicide-sprayed potted pear trees, respectively. Results confirmed distribution of isolates resistant to fenarimol, hexaconazole, and difenoconazole in the field populations. Importantly, results from tests in culture did not fully correlate with those from tests in planta. Due to phenotypic instability of resistance and poor sporulation of this pathogen in culture, resistance is generally assessed by laborious and time-consuming inoculation with conidia collected from a field. To improve the result interpretation from in vitro tests, the isolates were genotyped: the CYP51 gene which encodes the target sterol 14α-demethylase was sequenced and various mutations have been detected in the coding sequence of DMI-resistant isolates. In addition to the detected single nucleotide polymorphisms, alternative mechanisms, not based on changes in the structure of the target protein, may also increase DMI resistance. Development of molecular methods for the diagnosis of DMI resistance seems to be challenging in V. nashicola.
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Affiliation(s)
- Hideo Ishii
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba 305-8572, Japan;
- National Institute for Agro-Environmental Sciences, Kannondai 3-1-3, Tsukuba 305-8604, Japan;
- Department of Agriculture, Kibi International University, Sareo 370-1, Shichi, Minami-Awaji 656-0484, Japan
| | - Hans Jorgen Cools
- Syngenta, Jealott’s Hill International Research Centre, Bracknell RG42 6EY, UK;
| | - Kumiko Nishimura
- National Institute for Agro-Environmental Sciences, Kannondai 3-1-3, Tsukuba 305-8604, Japan;
| | - Lorenzo Borghi
- Syngenta Crop Protection AG, Werk Stein, Schaffhauserstrasse, WST.820.2.79, CH-4332 Stein, Switzerland;
| | - Kenji Kikuhara
- Fukuoka Agriculture and Forestry Research Center, Yoshiki 587, Chikushino 818-8549, Japan;
| | - Yuichi Yamaoka
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba 305-8572, Japan;
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Hu M, Chen S. Non-Target Site Mechanisms of Fungicide Resistance in Crop Pathogens: A Review. Microorganisms 2021; 9:microorganisms9030502. [PMID: 33673517 PMCID: PMC7997439 DOI: 10.3390/microorganisms9030502] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Revised: 02/18/2021] [Accepted: 02/23/2021] [Indexed: 01/15/2023] Open
Abstract
The rapid emergence of resistance in plant pathogens to the limited number of chemical classes of fungicides challenges sustainability and profitability of crop production worldwide. Understanding mechanisms underlying fungicide resistance facilitates monitoring of resistant populations at large-scale, and can guide and accelerate the development of novel fungicides. A majority of modern fungicides act to disrupt a biochemical function via binding a specific target protein in the pathway. While target-site based mechanisms such as alternation and overexpression of target genes have been commonly found to confer resistance across many fungal species, it is not uncommon to encounter resistant phenotypes without altered or overexpressed target sites. However, such non-target site mechanisms are relatively understudied, due in part to the complexity of the fungal genome network. This type of resistance can oftentimes be transient and noninheritable, further hindering research efforts. In this review, we focused on crop pathogens and summarized reported mechanisms of resistance that are otherwise related to target-sites, including increased activity of efflux pumps, metabolic circumvention, detoxification, standing genetic variations, regulation of stress response pathways, and single nucleotide polymorphisms (SNPs) or mutations. In addition, novel mechanisms of drug resistance recently characterized in human pathogens are reviewed in the context of nontarget-directed resistance.
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Affiliation(s)
- Mengjun Hu
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, USA
- Correspondence: (M.H.); (S.C.)
| | - Shuning Chen
- Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- Correspondence: (M.H.); (S.C.)
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Junqueira VB, Müller C, Rodrigues AA, Amaral TS, Batista PF, Silva AA, Costa AC. Do fungicides affect the physiology, reproductive development and productivity of healthy soybean plants? PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2021; 172:104754. [PMID: 33518047 DOI: 10.1016/j.pestbp.2020.104754] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 11/21/2020] [Accepted: 11/28/2020] [Indexed: 06/12/2023]
Abstract
Fungicides are widely used to control diseases in soybean crops. We hypothesized that fungicides applied to healthy soybean plants compromise the plant's physiology, affect the reproductive process and reduce crop productivity. We aimed to evaluate the photosynthetic process, pollen grain viability and yield components of soybean plants exposed to three commercial fungicides. The experiment was performed twice using soybean cultivar SYN 1378C, disease-free plants, with four treatments: i) control treatment (without any fungicide application); ii) cyproconazole 150 g L-1 + difenoconazole 250 g L-1 (CPZ + DFZ; 250 mL ha-1; without adjuvant); iii) azoxystrobin 300 g Kg-1 + benzovindiflupyr 150 g Kg-1 (AZB + BZP; 200 g ha-1; Nimbus® adjuvant (Syngenta)); and iv) propiconazole 250 g L-1 + difenoconazole 250 g L-1 (PPZ + DFZ; 150 mL ha-1; without adjuvant) in both soybean pre-bloom (V8) and bloom (R1) developmental stages. The experimental design was randomized blocks with four replicates. Phytotoxicity, gas exchange and chlorophyll a fluorescence traits, pollen grain viability, pollen grain germination, flower abortion and soybean production components were evaluated. The fungicides did not affect the physiological traits, pollen grain germination and crop yield.
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Affiliation(s)
- Verônica Barbosa Junqueira
- Ecophysiology and Plant Productivity Laboratory, Goiano Federal Institute of Science and Technology - Campus Rio Verde, P.O. Box 66, 75901-970 Rio Verde, GO, Brazil
| | - Caroline Müller
- Ecophysiology and Plant Productivity Laboratory, Goiano Federal Institute of Science and Technology - Campus Rio Verde, P.O. Box 66, 75901-970 Rio Verde, GO, Brazil
| | - Arthur Almeida Rodrigues
- Laboratory of Plant Anatomy, Goiano Federal Institute of Science and Technology - Campus Rio Verde, P.O. Box 66, 75901-970 Rio Verde, GO, Brazil
| | - Thales Simioni Amaral
- Ecophysiology and Plant Productivity Laboratory, Goiano Federal Institute of Science and Technology - Campus Rio Verde, P.O. Box 66, 75901-970 Rio Verde, GO, Brazil
| | - Priscila Ferreira Batista
- Ecophysiology and Plant Productivity Laboratory, Goiano Federal Institute of Science and Technology - Campus Rio Verde, P.O. Box 66, 75901-970 Rio Verde, GO, Brazil
| | - Adinan Alves Silva
- Ecophysiology and Plant Productivity Laboratory, Goiano Federal Institute of Science and Technology - Campus Rio Verde, P.O. Box 66, 75901-970 Rio Verde, GO, Brazil
| | - Alan Carlos Costa
- Ecophysiology and Plant Productivity Laboratory, Goiano Federal Institute of Science and Technology - Campus Rio Verde, P.O. Box 66, 75901-970 Rio Verde, GO, Brazil.
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20
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Zhang C, Imran M, Xiao L, Hu Z, Li G, Zhang F, Liu X. Difenoconazole Resistance Shift in Botrytis cinerea From Tomato in China Associated With Inducible Expression of CYP51. PLANT DISEASE 2021; 105:400-407. [PMID: 32729807 DOI: 10.1094/pdis-03-20-0508-re] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Gray mold caused by Botrytis cinerea is one of the most important diseases in tomato. It can be controlled effectively by demethylation inhibitor (DMI) fungicides, but their resistance status after long-term use in the field is unclear. The baseline sensitivity to difenoconazole of 142 B. cinerea isolates from China with no history of DMI usage was characterized, with a mean effective concentration for 50% mycelial growth inhibition (EC50) of 0.97 ± 0.50 μg/ml. EC50 values for difenoconazole sensitivity of another 248 isolates collected in 2011 and 2016 ranged from 0.04 to 11.99 μg/ml, and the frequency of difenoconazole sensitivity formed a nonnormal distribution curve. Detached fruit studies revealed that isolates with EC50 values of approximately 6.00 μg/ml were not controlled effectively. The mean EC50 of the resistant isolates changed from 6.74 to 8.65 μg/ml between 2011 and 2016. Positive cross-resistance was only observed between difenoconazole and two DMIs. One dual resistant isolate and one triple resistant isolate were found among the difenoconazole-resistant isolates collected in 2016, associated with point mutations in corresponding target proteins of the fungicides azoxystrobin and fludioxonil. This indicated that B. cinerea not only showed higher difenoconazole resistance levels but gradually changed from single to multiple fungicide resistance over time. No amino acid variation was found in the CYP51 protein. In the absence of difenoconazole, the relative expression of CYP51 was not significantly different in sensitive and resistant isolates. Induced expression of CYP51 is an important determinant of DMI resistance in B. cinerea from tomato. However, nucleotide variants found in the upstream region had no association with the fungicide resistance phenotype. These results will be helpful for the management of B. cinerea in the field.
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Affiliation(s)
- Can Zhang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Muhammad Imran
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Lu Xiao
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Zhihong Hu
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Guixiang Li
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling 712100, China
| | - Fan Zhang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Xili Liu
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling 712100, China
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21
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Wang Y, Jiang L, Wang MM, Feng JT. Baseline sensitivity and action mechanism of the sterol demethylation inhibitor flusilazole to Valsa mali. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2021; 171:104722. [PMID: 33357544 DOI: 10.1016/j.pestbp.2020.104722] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/03/2020] [Accepted: 10/09/2020] [Indexed: 06/12/2023]
Abstract
The apple Valsa canker caused by Valsa mali is a devastating branch disease that has seriously threatened the development of the apple industry worldwide. In current study, a total of 115 V. mali strains collected from different apple orchards in Shaanxi Province of China during 2016 and 2017 were tested for their sensitivity to flusilazole. The average EC50 (effective concentrations causing 50% mycelial growth inhibition) value of all tested strains for flusilazole was 0.0892 (±0.0036) μg/mL and the frequency distribution of the EC50 values was unimodal. Flusilazole exhibited both excellent protective and curative activity on detached apple branches, which was significantly better than the commonly used fungicide thiophanate-methyl. After flusilazole treatment, mycelia twisted with offshoot of top increased, the V. mali strains lost the ability of fruiting body production, and cell membrane permeability of the mycelia increased while ergosterol content and pectinase activity decreased. The expression of pectinase genes involved in virulence down-regulated after flusilazole treatment. This study is the first report on the baseline sensitivity of V. mali to flusilazole. These results indicated that flusilazole has a great potential to play an important role in the management of Valsa canker.
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Affiliation(s)
- Yong Wang
- College of plant protection, Northwest A & F University, Yangling 712100, Shaanxi, China
| | - Lin Jiang
- College of plant protection, Northwest A & F University, Yangling 712100, Shaanxi, China
| | - Miao-Miao Wang
- College of plant protection, Northwest A & F University, Yangling 712100, Shaanxi, China
| | - Jun-Tao Feng
- College of plant protection, Northwest A & F University, Yangling 712100, Shaanxi, China.
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22
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Weldon WA, Knaus BJ, Grünwald NJ, Havill JS, Block MH, Gent DH, Cadle-Davidson LE, Gadoury DM. Transcriptome-Derived Amplicon Sequencing Markers Elucidate the U.S. Podosphaera macularis Population Structure Across Feral and Commercial Plantings of Humulus lupulus. PHYTOPATHOLOGY 2021; 111:194-203. [PMID: 33044132 DOI: 10.1094/phyto-07-20-0299-fi] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Obligately biotrophic plant pathogens pose challenges in population genetic studies due to their genomic complexities and elaborate culturing requirements with limited biomass. Hop powdery mildew (Podosphaera macularis) is an obligately biotrophic ascomycete that threatens sustainable hop production. P. macularis populations of the Pacific Northwest (PNW) United States differ from those of the Midwest and Northeastern United States, lacking one of two mating types needed for sexual recombination and harboring two strains that are differentially aggressive on the cultivar Cascade and able to overcome the Humulus lupulus R-gene R6 (V6), respectively. To develop a high-throughput marker platform for tracking the flow of genotypes across the United States and internationally, we used an existing transcriptome of diverse P. macularis isolates to design a multiplex of 54 amplicon sequencing markers, validated across a panel of 391 U.S. samples and 123 international samples. The results suggest that P. macularis from U.S. commercial hop yards form one population closely related to P. macularis of the United Kingdom, while P. macularis from U.S. feral hop locations grouped with P. macularis of Eastern Europe. Included in this multiplex was a marker that successfully tracked V6-virulence in 65 of 66 samples with a confirmed V6-phenotype. A new qPCR assay for high-throughput genotyping of P. macularis mating type generated the highest resolution distribution map of P. macularis mating type to date. Together, these genotyping strategies enable the high-throughput and inexpensive tracking of pathogen spread among geographical regions from single-colony samples and provide a roadmap to develop markers for other obligate biotrophs.
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Affiliation(s)
- William A Weldon
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Brian J Knaus
- Department of Botany and Plant Pathology, Corvallis, OR 97331
| | - Niklaus J Grünwald
- U.S. Department of Agriculture-Agricultural Research Service Horticultural Crops Research Unit, Corvallis, OR 97330
| | - Joshua S Havill
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108
| | - Mary H Block
- Department of Botany and Plant Pathology, Corvallis, OR 97331
| | - David H Gent
- U.S. Department of Agriculture-Agricultural Research Service Forage Seed and Cereal Research Unit, Corvallis, OR 97331
| | - Lance E Cadle-Davidson
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
- U.S. Department of Agriculture-Agricultural Research Service Grape Genetics Research Unit, Geneva, NY 14456
| | - David M Gadoury
- Section of Plant Pathology and Plant-Microbe Biology, Cornell AgriTech, Cornell University, Geneva, NY 14456
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Mair WJ, Thomas GJ, Dodhia K, Hills AL, Jayasena KW, Ellwood SR, Oliver RP, Lopez-Ruiz FJ. Parallel evolution of multiple mechanisms for demethylase inhibitor fungicide resistance in the barley pathogen Pyrenophora teres f. sp. maculata. Fungal Genet Biol 2020; 145:103475. [DOI: 10.1016/j.fgb.2020.103475] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/11/2020] [Accepted: 09/25/2020] [Indexed: 10/23/2022]
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24
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Zou P, Zhang Y, Nshimiyimana JB, Cao Q, Yang Y, Geng H, Xiong L. Reconstruction of a Context-Specific Model Based on Genome-Scale Metabolic Simulation for Identification of Prochloraz Resistance Mechanisms in Penicillium digitatum. Microb Drug Resist 2020; 27:776-785. [PMID: 33180649 DOI: 10.1089/mdr.2020.0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Penicillium digitatum is the most destructive postharvest pathogen of citrus fruits, causing substantial economic losses. Prochloraz-resistant strains have emerged due to overuse of imidazole fungicides in agriculture. To study the prochloraz resistance mechanisms at the system level, a genome-scale metabolic model (GEM, iPD1512) of P. digitatum was reconstructed and constrained based on context-specific transcriptome data of the prochloraz-resistant strain, PdF6, from our previous work, a newly sequenced, context-specific transcriptome result of the major facilitator superfamily transporter-encoding gene mfs2 knockout mutant PdF6Δmfs2, and experimentally derived growth rate data. Through the model, iPD1512, the processes of prochloraz resistance in P. digitatum were well simulated. In detail, the growth rates of both wild-type and mutant P. digitatum under different prochloraz concentrations were simulated using constraint-based reconstruction and analysis. The growth rates of the mutant strains (sterol regulatory element-binding protein-encoding gene sreA knockout mutant PdF6ΔsreA and PdF6Δmfs2) were calculated and confirmed to be consistent with the simulation results. Furthermore, correlations between genes and prochloraz resistance were predicted and showed a great difference when compared with correlation results based on p-values from the hypothesis testing used by comparative transcriptomics. To sum up, in contrast to traditional transcriptome analysis, the GEM provides a systemic and dynamic drug resistance mechanism, which might help to detect some key upstream regulatory genes, but with small expression changes, and might provide more efficient targets to control prochloraz-resistant P. digitatum.
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Affiliation(s)
- Piao Zou
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Yunze Zhang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Jean Bosco Nshimiyimana
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Qianwen Cao
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Yang Yang
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Hui Geng
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Li Xiong
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
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Unconventional Yeasts Are Tolerant to Common Antifungals, and Aureobasidium pullulans Has Low Baseline Sensitivity to Captan, Cyprodinil, and Difenoconazole. Antibiotics (Basel) 2020; 9:antibiotics9090602. [PMID: 32942551 PMCID: PMC7557980 DOI: 10.3390/antibiotics9090602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/09/2020] [Accepted: 09/11/2020] [Indexed: 01/16/2023] Open
Abstract
Many yeasts have demonstrated intrinsic insensitivity to certain antifungal agents. Unlike the fungicide resistance of medically relevant yeasts, which is highly undesirable, intrinsic insensitivity to fungicides in antagonistic yeasts intended for use as biocontrol agents may be of great value. Understanding how frequently tolerance exists in naturally occurring yeasts and their underlying molecular mechanisms is important for exploring the potential of biocontrol yeasts and fungicide combinations for plant protection. Here, yeasts were isolated from various environmental samples in the presence of different fungicides (or without fungicide as a control) and identified by sequencing the internal transcribed spacer (ITS) region or through matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Among 376 isolates, 47 taxa were identified, and Aureobasidium pullulans was the most frequently isolated yeast. The baseline sensitivity of this yeast was established for 30 isolates from different environmental samples in vitro to captan, cyprodinil, and difenoconazole. For these isolates, the baseline minimum inhibitory concentration (MIC50) values for all the fungicides were higher than the concentrations used for the control of plant pathogenic fungi. For some isolates, there was no growth inhibition at concentrations as high as 300 µg/mL for captan and 128 µg/mL for cyprodinil. This information provides insight into the presence of resistance among naturally occurring yeasts and allows the choice of strains for further mechanistic analyses and the assessment of A. pullulans for novel applications in combination with chemical agents and as part of integrated plant-protection strategies.
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Lichtner FJ, Gaskins VL, Cox KD, Jurick WM. Global transcriptomic responses orchestrate difenoconazole resistance in Penicillium spp. causing blue mold of stored apple fruit. BMC Genomics 2020; 21:574. [PMID: 32831018 PMCID: PMC7444271 DOI: 10.1186/s12864-020-06987-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 08/12/2020] [Indexed: 01/09/2023] Open
Abstract
Background Blue mold is a globally important and economically impactful postharvest disease of apples caused by multiple Penicillium spp. There are currently four postharvest fungicides registered for blue mold control, and some isolates have developed resistance manifesting in decay on fungicide-treated fruit during storage. To date, mechanisms of fungicide resistance have not been explored in this fungus using a transcriptomic approach. Results We have conducted a comparative transcriptomic study by exposing naturally-occurring difenoconazole (DIF) resistant (G10) and sensitive (P11) blue mold isolates to technical grade difenoconazole, an azole fungicide in the commercial postharvest product Academy (Syngenta Crop Protection, LLC). Dynamic changes in gene expression patterns were observed encompassing candidates involved in active efflux and transcriptional regulators between the resistant and sensitive isolates. Unlike other systems, 3 isoforms of cytochrome P450 monoxygenase (CYP51A-C) were discovered and expressed in both sensitive and resistant strains upon difenoconazole treatment. Active efflux pumps were coordinately regulated in the resistant isolate and were shown to mediate the global resistance response as their inhibition reversed the difenoconazole-resistant phenotype in vitro. Conclusions Our data support the observation that global transcriptional changes modulate difenoconazole resistance in Penicillium spp. While the dogma of CYP51 overexpression is supported in the resistant isolate, our studies shed light on additional new mechanisms of difenoconazole resistance on a global scale in Penicillium spp. These new findings broaden our fundamental understanding of azole fungicide resistance in fungi, which has identified multiple genetic targets, that can be used for the detection, management, and abatement of difenoconazole-resistant blue mold isolates during long-term storage of apples.
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Affiliation(s)
- Franz J Lichtner
- Geisel School of Medicine, Dartmouth College, Hanover, NH, 03755, USA.
| | - Verneta L Gaskins
- U.S. Department of Agriculture-Agricultural Research Service, Beltsville, MD, 20705, USA
| | - Kerik D Cox
- Plant Pathology and Plant-Microbe Biology Section, Cornell University, Geneva, NY, 14456-0462, USA
| | - Wayne M Jurick
- U.S. Department of Agriculture-Agricultural Research Service, Beltsville, MD, 20705, USA.
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The Effects of Succinate Dehydrogenase Inhibitor Fungicide Dose and Mixture on Development of Resistance in Venturia inaequalis. Appl Environ Microbiol 2020; 86:AEM.01196-20. [PMID: 32631859 DOI: 10.1128/aem.01196-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 06/28/2020] [Indexed: 11/20/2022] Open
Abstract
Understanding how fungicide application practices affect selection for fungicide resistance is imperative for continued sustainable agriculture. Here, we examined the effect of field applications of the succinate dehydrogenase inhibitor (SDHI) fluxapyroxad at different doses and mixtures on the SDHI sensitivity of Venturia inaequalis, the apple scab pathogen. Fungicide applications were part of selection programs involving different doses (high or low) and mixtures (with a second single-site fungicide or a multisite fungicide). These programs were tested in two apple orchards over 4 years to determine potential cumulative selection effects on resistance. Each year after program applications, apple scab lesions were collected, and relative growth assays were conducted to understand shifts in fluxapyroxad sensitivity. After 4 years, there was a trend toward a reduction in sensitivity to fluxapyroxad for most selection programs in comparison to that in the non-selective-pressure control. In most years, the selection program plots treated with low-dose fluxapyroxad applications resulted in a larger number of isolates with reduced sensitivity, supporting the use of higher doses for disease management. Few significant differences (P < 0.05) in fungicide sensitivity were observed between isolates collected from plots where fungicide mixtures were applied compared to that in untreated plots, supporting the use of multiple modes of action in field applications. In all, appropriate doses and mixtures may contribute to increased longevity of SDHI fungicides used on perennial crops like apples.IMPORTANCE Of much debate is the effect of fungicide application dose on resistance development, as fungicide resistance is a critical barrier to effective disease management in agricultural systems. Our field study in apples investigated the effect of fungicide application dose and mixture on the selection of succinate dehydrogenase inhibitor resistance in Venturia inaequalis, a fungal pathogen that causes the economically important disease apple scab. Understanding how to best delay the development of resistance can result in increased efficacy, fewer applications, and sustainable fungicide use. Results from this study may have relevance to other perennial crops that require multiple fungicide applications and that are impacted by the development of resistance.
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Zhang Y, Zhou Q, Tian P, Li Y, Duan G, Li D, Zhan J, Chen F. Induced expression of CYP51 associated with difenoconazole resistance in the pathogenic Alternaria sect. on potato in China. PEST MANAGEMENT SCIENCE 2020; 76:1751-1760. [PMID: 31785067 DOI: 10.1002/ps.5699] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/25/2019] [Accepted: 11/26/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Early blight caused by Alternaria spp. is amongst the most important diseases in potato. Demethylation inhibitor (DMI) fungicides are widely used to control the disease but long-term use may decrease its control efficacy due to fungicide resistance. This study investigated the occurrence of difenoconazole resistance in Alternaria spp. and molecular resistant mechanisms. RESULTS EC50 values of 160 isolates to difenoconazole ranged from 0.026 μg mL-1 to 15.506 μg mL-1 and the frequency of difenoconazole sensitivity formed a non-normal distribution curve with a major and a minor peak. Isolates with EC50 values of 4.121 and 5.461 μg mL-1 were not controlled effectively at fungicide doses of 50 and 100 μg mL-1 . Cross-resistance was observed between DMI fungicides difenoconazole and propiconazole, but not between difenoconazole and other fungicide groups, including boscalid, iprodione, or carbendazim. The CYP51gene was 1673 bp encoding 525 amino acids in length and contained two introns. All sensitive and resistant isolates had the identical amino acid sequence of CYP51, with the exception of one resistant isolate carrying a mutation of R511W. A 6 bp insertion in the upstream region was observed in half of the resistant isolates. In the absence of propiconazole, the relative expression of CYP51 was not significantly different in sensitive and resistant isolates. In the presence of difenoconazole, expression of CYP51 gene was induced significantly in the DMI-resistant isolates but not in the sensitive ones. CONCLUSION Induced expression of CYP51 in resistant isolates exposed to difenoconazole is an important determinant for DMI resistance in potato pathogens Alternaria sect. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Yue Zhang
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Qian Zhou
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Peiyu Tian
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yuan Li
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Guohua Duan
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Dongliang Li
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jiasui Zhan
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Fengping Chen
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
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29
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Lichtner FJ, Jurick WM, Ayer KM, Gaskins VL, Villani SM, Cox KD. A Genome Resource for Several North American Venturia inaequalis Isolates with Multiple Fungicide Resistance Phenotypes. PHYTOPATHOLOGY 2020; 110:544-546. [PMID: 31729927 DOI: 10.1094/phyto-06-19-0222-a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The apple scab pathogen, Venturia inaequalis, is among the most economically important fungal pathogens that affects apples. Fungicide applications are an essential part of disease management. Implementation of cultural practices and genetic sources of resistance in the host are vital components of scab management. This is the first presentation of multiple, high quality, well-annotated genomes of four North American V. inaequalis isolates having both sensitive and multiple fungicide resistance phenotypes. We envision that these isolates will enable investigations into fungicide resistance mechanisms, exploring fungal virulence factors and delineating phylogenomic relationships among apple scab isolates from around the world.
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Affiliation(s)
- Franz J Lichtner
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831
- Food Quality Laboratory, U.S. Department of Agriculture-Agriculture Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705
| | - Wayne M Jurick
- Food Quality Laboratory, U.S. Department of Agriculture-Agriculture Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705
| | - Katrin M Ayer
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
| | - Verneta L Gaskins
- Food Quality Laboratory, U.S. Department of Agriculture-Agriculture Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705
| | - Sara M Villani
- Department of Entomology and Plant Pathology, Mountain Horticulture and Crops Research & Extension Center, North Carolina State University, Mills River, NC 28759
| | - Kerik D Cox
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456
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Meyers E, Arellano C, Cowger C. Sensitivity of the U.S. Blumeria graminis f. sp. tritici Population to Demethylation Inhibitor Fungicides. PLANT DISEASE 2019; 103:3108-3116. [PMID: 31657998 DOI: 10.1094/pdis-04-19-0715-re] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, is managed in the United States with cultivar resistance and foliar fungicides. Despite high levels of fungicide sensitivity in other cereal mildew populations, fungicide sensitivity of U.S. B. graminis f. sp. tritici has never been evaluated. Almost 400 B. graminis f. sp. tritici isolates were collected from 15 U.S. states over 2 years and phenotyped for sensitivity to two widely used demethylation inhibitor (DMI) fungicides, tebuconazole and prothioconazole. A large range of sensitivity to both DMIs was observed, with more insensitive isolates originating from the eastern United States (Great Lakes, Mid-Atlantic, and Southeast regions) and more sensitive isolates from central states (Plains region, Arkansas, and Missouri). Cross-resistance was indicated by a positive although weak association between tebuconazole and prothioconazole sensitivities at all levels of analysis (EC50 values, P < 0.0001). A possible fitness cost was also associated with prothioconazole insensitivity (P = 0.0307) when analyzed at the state population level. This is the first assessment of fungicide sensitivity in the U.S. B. graminis f. sp. tritici population, and it produced evidence of regional selection for reduced DMI efficacy. The observation of reduced sensitivity to DMI fungicides in the eastern United States underlines the importance of rotating between chemistry classes to maintain the effectiveness of DMIs in U.S. wheat production. Although cross-resistance was demonstrated, variability in the relationship of EC50 values for tebuconazole and prothioconazole also suggests that multiple mechanisms influence B. graminis f. sp. tritici isolate responses to these two DMI fungicides.
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Affiliation(s)
- Emily Meyers
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695
| | - Consuelo Arellano
- Department of Statistics, North Carolina State University, Raleigh, NC 27695
| | - Christina Cowger
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695
- United States Department of Agriculture, Agricultural Research Service, Raleigh, NC 27695
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Hay FS, Sharma S, Hoepting C, Strickland D, Luong K, Pethybridge SJ. Emergence of Stemphylium Leaf Blight of Onion in New York Associated With Fungicide Resistance. PLANT DISEASE 2019; 103:3083-3092. [PMID: 31596693 DOI: 10.1094/pdis-03-19-0676-re] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A complex of foliar diseases affects onion production in New York, including Botrytis leaf blight (Botrytis squamosa), purple blotch (Alternaria porri), Stemphylium leaf blight (SLB; Stemphylium vesicarium), and downy mildew (Peronospora destructor). Surveys were conducted in 2015 and 2016 to evaluate the cause of severe premature foliar dieback in New York onion fields. SLB was the most prevalent disease among fields with the greatest incidence, surpassing downy mildew, purple blotch, and Botrytis leaf blight. Sequencing of the internal transcribed spacer region of ribosomal DNA and the glyceraldedyhe-3-phosphate dehydrogenase and calmodulin genes identified S. vesicarium as the species most commonly associated with SLB. S. vesicarium was typically associated with a broad range of necrotic symptoms but, most commonly, dieback of leaf tips and asymmetric lesions that often extended over the entire leaf. Because of the intensive use of fungicides for foliar disease control in onion crops in New York, the sensitivity of S. vesicarium populations to various fungicides with site-specific modes of action was evaluated. Sensitivity of S. vesicarium isolates collected in 2016 to the quinone outside inhibitor (QoI) fungicide, azoxystrobin, was tested using a conidial germination assay. Isolates representing a broad range of QoI sensitivities were selected for sequencing of the cytochrome b gene to evaluate the presence of point mutations associated with insensitivity to azoxystrobin. The G143A mutation was detected in all 74 S. vesicarium isolates with an azoxystrobin-insensitive phenotype (effective concentrations reducing conidial germination by 50%, EC50 = 0.2 to 46.7 µg of active ingredient [a.i.]/ml) and was not detected in all 31 isolates with an azoxystrobin-sensitive phenotype (EC50 = 0.01 to 0.16 µg a.i./ml). The G143A mutation was also associated with insensitivity to another QoI fungicide, pyraclostrobin. Sensitivity to other selected fungicides commonly used in onion production in New York was evaluated using a mycelial growth assay and identified isolates with insensitivity to boscalid, cyprodinil, and pyrimethanil, but not difenoconazole. The frequency of isolates sensitive to iprodione, fluxapyroxad, and fluopyram was high (93.5 to 93.6%). This article discusses the emergence of SLB as dominant in the foliar disease complex affecting onion in New York and the complexities of management posed by resistance to fungicides with different modes of action.
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Affiliation(s)
- Frank S Hay
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Sandeep Sharma
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Christy Hoepting
- Cornell Vegetable Program, Cornell Cooperative Extension, Albion, NY 14411
| | - David Strickland
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Karen Luong
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
| | - Sarah J Pethybridge
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech, Cornell University, Geneva, NY 14456
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Stravoravdis S, LeBlanc NR, Marra RE, Crouch JA, Hulvey JP. Widespread Occurrence of a CYP51A Pseudogene in Calonectria pseudonaviculata. MYCOBIOLOGY 2019; 48:44-50. [PMID: 32158605 PMCID: PMC7048176 DOI: 10.1080/12298093.2019.1689600] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 09/27/2019] [Accepted: 10/14/2019] [Indexed: 06/10/2023]
Abstract
Calonectria pseudonaviculata and C. henricotiae are two closely related fungal species responsible for boxwood blight disease of ornamental shrubs (Buxus spp.) in the U.S. and Europe. A previous study has shown isolates of the latter species, which is restricted to Europe, to be less sensitive to tetraconazole, an azole fungicide. In this study, we have analyzed the CYP51 paralogs for polymorphism in 26 genomes, representing geographically disparate populations of C. pseudonaviculata (n = 19) and C. henricotiae (n = 7), from the U.S., Europe, Asia, and New Zealand. The presence of a CYP51A pseudogene and lack of a functional CYP51A paralog in all C. pseudonaviculata genomes examined is a novel discovery for fungi and could have implications for the evolution of resistance to antifungal chemicals.
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Affiliation(s)
| | - Nicholas R. LeBlanc
- Mycology and Nematology Genetic Diversity and Biology Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA
- Oak Ridge Institute for Science and Education, ARS Research Participation Program, Oak Ridge, TN, USA
| | - Robert E. Marra
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT, USA
| | - Jo Anne Crouch
- Mycology and Nematology Genetic Diversity and Biology Laboratory, United States Department of Agriculture, Agricultural Research Service, Beltsville, MD, USA
| | - Jonathan P. Hulvey
- Biology Department, Eastern Connecticut State University, Willimantic, CT, USA
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Desmyttere H, Deweer C, Muchembled J, Sahmer K, Jacquin J, Coutte F, Jacques P. Antifungal Activities of Bacillus subtilis Lipopeptides to Two Venturia inaequalis Strains Possessing Different Tebuconazole Sensitivity. Front Microbiol 2019; 10:2327. [PMID: 31695685 PMCID: PMC6817503 DOI: 10.3389/fmicb.2019.02327] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 09/24/2019] [Indexed: 01/27/2023] Open
Abstract
Within the framework of biocontrol development, three natural substances produced by Bacillus subtilis, called lipopeptides, have been studied: fengycin (F), surfactin (S), and mycosubtilin (M). Their antifungal properties were tested in vitro, in liquid medium, on two strains of Venturia inaequalis, ascomycete fungi causing apple scab. These two strains were, respectively sensitive and less sensitive to tebuconazole, an active substance of the triazole family. These three molecules were tested on their own, in binary (FS, FM, SM) and ternary mixtures (FSM). The antifungal activities of lipopeptides were estimated by calculating an IC50, compared to tebuconazole chemical substance. In tests involving the sensitive strain, all lipopeptide modalities exhibited antifungal activity. However, modalities involving fengycin and its mixtures exhibited the best antifungal activities; the activity of fengycin alone being very similar to that of tebuconazole. Interestingly, regarding the strain with reduced sensitivity to tebuconazole, surfactin and fengycin alone were not efficient while mycosubtilin and the different mixtures showed interesting antifungal activities. Specifically, the antifungal activity of FS and FSM mixture were equivalent to that of tebuconazole. For both fungal strains, microscopic observations revealed important morphological modifications in the presence of fengycin and in a less important proportion in the presence of surfactin but not in the presence of mycosubtilin. Overall, this study highlights the diversity in mode of action of lipopeptides on apple scab strains.
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Affiliation(s)
- Hélène Desmyttere
- Univ. Lille, INRA, ISA-Yncréa, Univ. Artois, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, Lille, France
| | - Caroline Deweer
- Univ. Lille, INRA, ISA-Yncréa, Univ. Artois, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, Lille, France
| | - Jérôme Muchembled
- Univ. Lille, INRA, ISA-Yncréa, Univ. Artois, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, Lille, France
| | - Karin Sahmer
- Civil and Geo-Environmental Engineering Laboratory (LGCgE), ISA - Yncréa, Lille, France
| | - Justine Jacquin
- Univ. Lille, INRA, ISA-Yncréa, Univ. Artois, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, Lille, France
| | - François Coutte
- Univ. Lille, INRA, ISA-Yncréa, Univ. Artois, Univ. Littoral Côte d'Opale, EA 7394 - ICV - Institut Charles Viollette, Lille, France
| | - Philippe Jacques
- MiPI, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
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Chong P, Vichou AE, Schouten HJ, Meijer HJG, Arango Isaza RE, Kema GHJ. Pfcyp51 exclusively determines reduced sensitivity to 14α-demethylase inhibitor fungicides in the banana black Sigatoka pathogen Pseudocercospora fijiensis. PLoS One 2019; 14:e0223858. [PMID: 31622393 PMCID: PMC6797121 DOI: 10.1371/journal.pone.0223858] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Accepted: 09/30/2019] [Indexed: 11/27/2022] Open
Abstract
The haploid fungus Pseudocercospora fijiensis causes black Sigatoka in banana and is chiefly controlled by extensive fungicide applications, threatening occupational health and the environment. The 14α-Demethylase Inhibitors (DMIs) are important disease control fungicides, but they lose sensitivity in a rather gradual fashion, suggesting an underlying polygenic genetic mechanism. In spite of this, evidence found thus far suggests that P. fijiensis cyp51 gene mutations are the main responsible factor for sensitivity loss in the field. To better understand the mechanisms involved in DMI resistance, in this study we constructed a genetic map using DArTseq markers on two F1 populations generated by crossing two different DMI resistant strains with a sensitive strain. Analysis of the inheritance of DMI resistance in the F1 populations revealed two major and discrete DMI-sensitivity groups. This is an indicative of a single major responsible gene. Using the DMI-sensitivity scorings of both F1 populations and the generation of genetic linkage maps, the sensitivity causal factor was located in a single genetic region. Full agreement was found for genetic markers in either population, underlining the robustness of the approach. The two maps indicated a similar genetic region where the Pfcyp51 gene is found. Sequence analyses of the Pfcyp51 gene of the F1 populations also revealed a matching bimodal distribution with the DMI resistant. Amino acid substitutions in P. fijiensis CYP51 enzyme of the resistant progeny were previously correlated with the loss of DMI sensitivity. In addition, the resistant progeny inherited a Pfcyp51 gene promoter insertion, composed of a repeat element with a palindromic core, also previously correlated with increased gene expression. This genetic approach confirms that Pfcyp51 is the single explanatory gene for reduced sensitivity to DMI fungicides in the analysed P. fijiensis strains. Our study is the first genetic analysis to map the underlying genetic factors for reduced DMI efficacy.
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Affiliation(s)
- Pablo Chong
- ESPOL Polythecnic University, Escuela Superior Politécnica del Litoral, ESPOL, Centro de Investigaciones Biotecnológicas del Ecuador, Laboratorio de Fitopatología, Guayaquil, Ecuador
- Laboratory of Phytopathology, Wageningen University and Research, The Netherlands, Wageningen, the Netherlands
| | - Aikaterini-Eleni Vichou
- Laboratory of Phytopathology, Wageningen University and Research, The Netherlands, Wageningen, the Netherlands
| | - Henk J. Schouten
- Laboratory of Phytopathology, Wageningen University and Research, The Netherlands, Wageningen, the Netherlands
| | - Harold J. G. Meijer
- Laboratory of Phytopathology, Wageningen University and Research, The Netherlands, Wageningen, the Netherlands
| | - Rafael E. Arango Isaza
- Escuela de Biociencias, Faculta de Ciencias, Universidad Nacional de Colombia -Sede Medellín (UNALMED), Medellín, Colombia
- Unidad de biotecnología (UNALMED-CIB), Corporación para Investigaciones Biológicas, Medellín, Colombia
| | - Gert H. J. Kema
- Laboratory of Phytopathology, Wageningen University and Research, The Netherlands, Wageningen, the Netherlands
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Yang LN, He MH, Ouyang HB, Zhu W, Pan ZC, Sui QJ, Shang LP, Zhan J. Cross-resistance of the pathogenic fungus Alternaria alternata to fungicides with different modes of action. BMC Microbiol 2019; 19:205. [PMID: 31477005 PMCID: PMC6720428 DOI: 10.1186/s12866-019-1574-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 08/22/2019] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Cross-resistance, a phenomenon that a pathogen resists to one antimicrobial compound also resists to one or several other compounds, is one of major threats to human health and sustainable food production. It usually occurs among antimicrobial compounds sharing the mode of action. In this study, we determined the sensitivity profiles of Alternaria alternata, a fungal pathogen which can cause diseases in many crops to two fungicides (mancozeb and difenoconazole) with different mode of action using a large number of isolates (234) collected from seven potato fields across China. RESULTS We found that pathogens could also develop cross resistance to fungicides with different modes of action as indicated by a strong positive correlation between mancozeb and difenoconazole tolerances to A. alternata. We also found a positive association between mancozeb tolerance and aggressiveness of A. alternata, suggesting no fitness penalty of developing mancozeb resistance in the pathogen and hypothesize that mechanisms such as antimicrobial compound efflux and detoxification that limit intercellular accumulation of natural/synthetic chemicals in pathogens might account for the cross-resistance and the positive association between pathogen aggressiveness and mancozeb tolerance. CONCLUSIONS The detection of cross-resistance among different classes of fungicides suggests that the mode of action alone may not be an adequate sole criterion to determine what components to use in the mixture and/or rotation of fungicides in agricultural and medical sects. Similarly, the observation of a positive association between the pathogen's aggressiveness and tolerance to mancozeb suggests that intensive application of site non-specific fungicides might simultaneously lead to reduced fungicide resistance and enhanced ability to cause diseases in pathogen populations, thereby posing a greater threat to agricultural production and human health. In this case, the use of evolutionary principles in closely monitoring populations and the use of appropriate fungicide applications are important for effective use of the fungicides and durable infectious disease management.
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Affiliation(s)
- Li-Na Yang
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou, 350002, Fujian, China
| | - Meng-Han He
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou, 350002, Fujian, China
| | - Hai-Bing Ouyang
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou, 350002, Fujian, China
| | - Wen Zhu
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou, 350002, Fujian, China
| | - Zhe-Chao Pan
- Yunnan Academy of Agricultural Sciences, Industrial Crops Research Institute, Kunming, Yunnan, China
| | - Qi-Jun Sui
- Yunnan Academy of Agricultural Sciences, Industrial Crops Research Institute, Kunming, Yunnan, China
| | - Li-Ping Shang
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agricultural and Forestry University, Fuzhou, 350002, Fujian, China
| | - Jiasui Zhan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China.
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
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Diaz‐Trujillo C, Chong P, Stergiopoulos I, Cordovez V, Guzman M, De Wit PJGM, Meijer HJG, Scalliet G, Sierotzki H, Lilia Peralta E, Arango Isaza RE, Kema GHJ. A new mechanism for reduced sensitivity to demethylation-inhibitor fungicides in the fungal banana black Sigatoka pathogen Pseudocercospora fijiensis. MOLECULAR PLANT PATHOLOGY 2018; 19:1491-1503. [PMID: 29105293 PMCID: PMC6637983 DOI: 10.1111/mpp.12637] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 10/27/2017] [Accepted: 10/31/2017] [Indexed: 05/12/2023]
Abstract
The Dothideomycete Pseudocercospora fijiensis, previously Mycosphaerella fijiensis, is the causal agent of black Sigatoka, one of the most destructive diseases of bananas and plantains. Disease management depends on fungicide applications, with a major contribution from sterol demethylation-inhibitors (DMIs). The continued use of DMIs places considerable selection pressure on natural P. fijiensis populations, enabling the selection of novel genotypes with reduced sensitivity. The hitherto explanatory mechanism for this reduced sensitivity was the presence of non-synonymous point mutations in the target gene Pfcyp51, encoding the sterol 14α-demethylase enzyme. Here, we demonstrate a second mechanism involved in DMI sensitivity of P. fijiensis. We identified a 19-bp element in the wild-type (wt) Pfcyp51 promoter that concatenates in strains with reduced DMI sensitivity. A polymerase chain reaction (PCR) assay identified up to six Pfcyp51 promoter repeats in four field populations of P. fijiensis in Costa Rica. We used transformation experiments to swap the wt promoter of a sensitive field isolate with a promoter from a strain with reduced DMI sensitivity that comprised multiple insertions. Comparative in vivo phenotyping showed a functional and proportional up-regulation of Pfcyp51, which consequently decreased DMI sensitivity. Our data demonstrate that point mutations in the Pfcyp51 coding domain, as well as promoter inserts, contribute to the reduced DMI sensitivity of P. fijiensis. These results provide new insights into the importance of the appropriate use of DMIs and the need for the discovery of new molecules for black Sigatoka management.
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Affiliation(s)
- Caucasella Diaz‐Trujillo
- Wageningen University and Research, Wageningen Plant Research6700 AA Wageningenthe Netherlands
- Wageningen University and ResearchLaboratory for Phytopathology6700 AA Wageningenthe Netherlands
| | - Pablo Chong
- Wageningen University and Research, Wageningen Plant Research6700 AA Wageningenthe Netherlands
- Wageningen University and ResearchLaboratory for Phytopathology6700 AA Wageningenthe Netherlands
- Escuela Superior Politécnica del Litoral, ESPOL, Centro de Investigaciones Biotecnológicas del Ecuador, CIBE, Laboratorio de FitopatologíaESPOL Polythecnic UniversityGuayaquil 09‐01‐5663Ecuador
| | - Ioannis Stergiopoulos
- Wageningen University and Research, Wageningen Plant Research6700 AA Wageningenthe Netherlands
- Department of Plant PathologyUniversity of California, DavisDavisCA 95616‐8751USA
| | - Viviane Cordovez
- Wageningen University and ResearchLaboratory for Phytopathology6700 AA Wageningenthe Netherlands
- Department of Microbial EcologyNetherlands Institute of EcologyWageningen 6708 PBthe Netherlands
| | - Mauricio Guzman
- Department of Phytopathology, National Banana Corporation of Costa Rica (CORBANA), La Rita de PococíLimón 6504‐1000Costa Rica
| | - Pierre J. G. M. De Wit
- Wageningen University and ResearchLaboratory for Phytopathology6700 AA Wageningenthe Netherlands
| | - Harold J. G. Meijer
- Wageningen University and Research, Wageningen Plant Research6700 AA Wageningenthe Netherlands
| | - Gabriel Scalliet
- Crop Protection Disease Control, Syngenta Crop Protection Münchwilen AGStein 4333Switzerland
| | - Helge Sierotzki
- Crop Protection Disease Control, Syngenta Crop Protection Münchwilen AGStein 4333Switzerland
| | - Esther Lilia Peralta
- Escuela Superior Politécnica del Litoral, ESPOL, Centro de Investigaciones Biotecnológicas del Ecuador, CIBE, Laboratorio de FitopatologíaESPOL Polythecnic UniversityGuayaquil 09‐01‐5663Ecuador
| | - Rafael E. Arango Isaza
- Plant Biotechnology UnitCorporación para Investigaciones Biológicas (CIB)Medellín 050034Colombia
- School of Biosciences, Faculty of SciencesNational University of ColombiaMedellín 050034Colombia
| | - Gerrit H. J. Kema
- Wageningen University and Research, Wageningen Plant Research6700 AA Wageningenthe Netherlands
- Wageningen University and ResearchLaboratory for Phytopathology6700 AA Wageningenthe Netherlands
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Qian H, Du J, Chi M, Sun X, Liang W, Huang J, Li B. The Y137H mutation in the cytochrome P450 FgCYP51B protein confers reduced sensitivity to tebuconazole in Fusarium graminearum. PEST MANAGEMENT SCIENCE 2018; 74:1472-1477. [PMID: 29274114 DOI: 10.1002/ps.4837] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 12/17/2017] [Accepted: 12/19/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND Fusarium graminearum is the main pathogen of Fusarium head blight (FHB), a worldwide plant disease and one of the most significant wheat diseases in China. Demethylation inhibitor (DMI) fungicides, such as tebuconazole (TEC), are widely used to control FHB, but long-term use leads to low efficacy against FHB. Earlier studies showed that DMI resistance is associated with the fungal sterol 14α-demethylase (cytochrome P450 CYP51) gene, and that point mutations in the CYP51 gene are the primary mechanism of resistance to DMI fungicides. The aims of this study were to clarify the molecular mechanisms of resistance to TEC and identify the binding sites on the FgCYP51B protein. RESULTS Site-directed mutagenesis was used to change the FgCYP51B gene of wild-type strain PH-1 from tyrosine to histidine at residue 137 (Y137H) to generate a mutant transformant, which was confirmed to be resistant to TEC compared with the parental strains. A three-dimensional FgCYP51B model was constructed, and molecular docking simulation studies were conducted to identify the optimum binding mode with TEC. The wild-type FgCYP51B protein displayed stronger affinity to TEC than that of the mutated FgCYP51B in the molecular docking analysis. CONCLUSION These results indicate that a Tyr137 amino acid mutation in the cytochrome P450 FgCYP51B could lead to resistance to TEC and that Y137 forms part of the tebuconazole-binding pocket. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Hengwei Qian
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao, PR China
| | - Juan Du
- College of Life Science, Qingdao Agricultural University, Qingdao, PR China
| | - Mengyu Chi
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao, PR China
| | - Xiaomei Sun
- College of Animation and Communication, Qingdao Agricultural University, Qingdao, PR China
| | - Wenxing Liang
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao, PR China
| | - Jinguang Huang
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao, PR China
| | - Baodu Li
- College of Plant Health and Medicine and Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao, PR China
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Plasticity of the MFS1 Promoter Leads to Multidrug Resistance in the Wheat Pathogen Zymoseptoria tritici. mSphere 2017; 2:mSphere00393-17. [PMID: 29085913 PMCID: PMC5656749 DOI: 10.1128/msphere.00393-17] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 09/21/2017] [Indexed: 11/20/2022] Open
Abstract
The ascomycete Zymoseptoria tritici is the causal agent of Septoria leaf blotch on wheat. Disease control relies mainly on resistant wheat cultivars and on fungicide applications. The fungus displays a high potential to circumvent both methods. Resistance against all unisite fungicides has been observed over decades. A different type of resistance has emerged among wild populations with multidrug-resistant (MDR) strains. Active fungicide efflux through overexpression of the major facilitator gene MFS1 explains this emerging resistance mechanism. Applying a bulk-progeny sequencing approach, we identified in this study a 519-bp long terminal repeat (LTR) insert in the MFS1 promoter, a relic of a retrotransposon cosegregating with the MDR phenotype. Through gene replacement, we show the insert as a mutation responsible for MFS1 overexpression and the MDR phenotype. Besides this type I insert, we found two different types of promoter inserts in more recent MDR strains. Type I and type II inserts harbor potential transcription factor binding sites, but not the type III insert. Interestingly, all three inserts correspond to repeated elements present at different genomic locations in either IPO323 or other Z. tritici strains. These results underline the plasticity of repeated elements leading to fungicide resistance in Z. tritici and which contribute to its adaptive potential. IMPORTANCE Disease control through fungicides remains an important means to protect crops from fungal diseases and to secure the harvest. Plant-pathogenic fungi, especially Zymoseptoria tritici, have developed resistance against most currently used active ingredients, reducing or abolishing their efficacy. While target site modification is the most common resistance mechanism against single modes of action, active efflux of multiple drugs is an emerging phenomenon in fungal populations reducing additionally fungicides' efficacy in multidrug-resistant strains. We have investigated the mutations responsible for increased drug efflux in Z. tritici field strains. Our study reveals that three different insertions of repeated elements in the same promoter lead to multidrug resistance in Z. tritici. The target gene encodes the membrane transporter MFS1 responsible for drug efflux, with the promoter inserts inducing its overexpression. These results underline the plasticity of repeated elements leading to fungicide resistance in Z. tritici.
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Junqueira VB, Costa AC, Boff T, Müller C, Mendonça MAC, Batista PF. Pollen viability, physiology, and production of maize plants exposed to pyraclostrobin+epoxiconazole. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2017; 137:42-48. [PMID: 28364803 DOI: 10.1016/j.pestbp.2016.09.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 09/20/2016] [Accepted: 09/23/2016] [Indexed: 06/07/2023]
Abstract
The use of fungicides in maize has been more frequent due to an increase in the incidence of diseases and also the possible physiological benefits that some of these products may cause. However, some of these products (e.g., strobilurins and triazoles) may interfere with physiological processes and the formation of reproductive organs. Therefore, the effect of these products on plants at different developmental stages needs to be better understood to reduce losses and maximize production. The effect of the fungicide pyraclostrobin+epoxiconazole (P+E) was evaluated at different growth stages in meiosis, pollen grain viability and germination, physiology, and production of maize plants in the absence of disease. An experiment was carried out with the hybrid DKB390 PROII and the application of pyraclostrobin+epoxiconazole at the recommended dose and an untreated control at 3 different timings (S1 - V10; S2 - V14; S3 - R1) with 5 replications. Gas exchange, chlorophyll fluorescence, pollen viability and germination, as well as the hundred-grain weight were evaluated. Anthers were collected from plants of S1 for cytogenetic analysis. The fungicide pyraclostrobin+epoxiconazole reduced the viability of pollen grains (1.4%), but this was not enough to reduce production. Moreover, no differences were observed in any of the other parameters analyzed, suggesting that P+E at the recommended dose and the tested stages does not cause toxic effects.
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Affiliation(s)
- Verônica Barbosa Junqueira
- Laboratório de Ecofisiologia e Produtividade Vegetal, Instituto Federal de Educação, Ciência e Tecnologia Goiano - Campus Rio Verde, Caixa Postal 66, 75901-970 Rio Verde, GO, Brazil.
| | - Alan Carlos Costa
- Laboratório de Ecofisiologia e Produtividade Vegetal, Instituto Federal de Educação, Ciência e Tecnologia Goiano - Campus Rio Verde, Caixa Postal 66, 75901-970 Rio Verde, GO, Brazil.
| | - Tatiana Boff
- Instituto Federal de Educação, Ciência e Tecnologia do Triângulo Mineiro - Campus Uberlândia, Caixa Postal 1020, 38400-970 Uberlândia, MG, Brazil.
| | - Caroline Müller
- Laboratório de Ecofisiologia e Produtividade Vegetal, Instituto Federal de Educação, Ciência e Tecnologia Goiano - Campus Rio Verde, Caixa Postal 66, 75901-970 Rio Verde, GO, Brazil.
| | - Maria Andréia Corrêa Mendonça
- Laboratório de Biotecnologia, Instituto Federal de Educação, Ciência e Tecnologia Goiano - Campus Rio Verde, Caixa Postal 66, 75901-970 Rio Verde, GO, Brazil.
| | - Priscila Ferreira Batista
- Laboratório de Ecofisiologia e Produtividade Vegetal, Instituto Federal de Educação, Ciência e Tecnologia Goiano - Campus Rio Verde, Caixa Postal 66, 75901-970 Rio Verde, GO, Brazil.
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