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Hassett K, Muria-Gonzalez MJ, Martin A, Karakaya A, Çelik Oğuz A, Bakonyi J, Knight NL, Prins R, Ellwood SR. Global Spread, Genetic Differentiation, and Selection of Barley Spot Form Net Blotch Isolates. PHYTOPATHOLOGY 2024; 114:1542-1553. [PMID: 38619562 DOI: 10.1094/phyto-11-23-0442-r] [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: 04/16/2024]
Abstract
Spot form net blotch, caused by Pyrenophora teres f. maculata, is a significant necrotrophic disease of barley that spread worldwide in the twentieth century. Genetic relationships were analyzed to determine the diversity, survival, and dispersal of a diverse collection of 346 isolates from Australia, Southern Africa, North America, Asia Minor, and Europe. The results, based on genome-wide DArTseq data, indicated that isolates from Turkey were the most differentiated with regional sub-structuring, together with individuals closely related to geographically distant genotypes. Elsewhere, population subdivision related to country of origin was evident, although low levels of admixturing was found that may represent rare genotypes or migration from unsampled populations. Canadian isolates were the next most diverged, and Australian and South African the most closely related. With the exception of Turkish isolates, multiple independent Cyp51A mutation events (which confer insensitivity to demethylation inhibitor fungicides) between countries and within regions was evident, with strong selection for a transposable element insertion at the 3' end of the promoter and counterselection elsewhere. Individuals from Western Australia shared genomic regions and Cyp51A haplotypes with South African isolates, suggesting a recent common origin. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Kealan Hassett
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Mariano Jordi Muria-Gonzalez
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Anke Martin
- Centre for Crop Health, University of Southern Queensland, Toowoomba, QLD 4350, Australia
| | - Aziz Karakaya
- Department of Plant Protection, Faculty of Agriculture, Ankara University, Dışkapı, Ankara 06110, Turkey
| | - Arzu Çelik Oğuz
- Department of Plant Protection, Faculty of Agriculture, Ankara University, Dışkapı, Ankara 06110, Turkey
| | - Jószef Bakonyi
- Plant Protection Institute, HUN-REN Centre for Agricultural Research, Herman Ottó str. 15, 1022 Budapest, Hungary
| | - Noel L Knight
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
- Centre for Crop Health, University of Southern Queensland, Toowoomba, QLD 4350, Australia
| | - Renée Prins
- CenGen (Pty) Ltd., Worcester, 6850, South Africa
| | - Simon R Ellwood
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
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Xi Y, Zhang J, Fan B, Sun M, Cao W, Liu X, Gai Y, Shen C, Wang H, Wang M. Transcriptome Analysis Reveals Potential Regulators of DMI Fungicide Resistance in the Citrus Postharvest Pathogen Penicillium digitatum. J Fungi (Basel) 2024; 10:360. [PMID: 38786715 PMCID: PMC11122302 DOI: 10.3390/jof10050360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/09/2024] [Accepted: 05/16/2024] [Indexed: 05/25/2024] Open
Abstract
Green mold, caused by Penicillium digitatum, is the major cause of citrus postharvest decay. Currently, the application of sterol demethylation inhibitor (DMI) fungicide is one of the main control measures to prevent green mold. However, the fungicide-resistance problem in the pathogen P. digitatum is growing. The regulatory mechanism of DMI fungicide resistance in P. digitatum is poorly understood. Here, we first performed transcriptomic analysis of the P. digitatum strain Pdw03 treated with imazalil (IMZ) for 2 and 12 h. A total of 1338 genes were up-regulated and 1635 were down-regulated under IMZ treatment for 2 h compared to control while 1700 were up-regulated and 1661 down-regulated under IMZ treatment for 12 h. The expression of about half of the genes in the ergosterol biosynthesis pathway was affected during IMZ stress. Further analysis identified that 84 of 320 transcription factors (TFs) were differentially expressed at both conditions, making them potential regulators in DMI resistance. To confirm their roles, three differentially expressed TFs were selected to generate disruption mutants using the CRISPR/Cas9 technology. The results showed that two of them had no response to IMZ stress while ∆PdflbC was more sensitive compared with the wild type. However, disruption of PdflbC did not affect the ergosterol content. The defect in IMZ sensitivity of ∆PdflbC was restored by genetic complementation of the mutant with a functional copy of PdflbC. Taken together, our results offer a rich source of information to identify novel regulators in DMI resistance.
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Affiliation(s)
- Yue Xi
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; (Y.X.); (J.Z.); (B.F.); (M.S.); (W.C.); (X.L.); (C.S.); (H.W.)
| | - Jing Zhang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; (Y.X.); (J.Z.); (B.F.); (M.S.); (W.C.); (X.L.); (C.S.); (H.W.)
| | - Botao Fan
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; (Y.X.); (J.Z.); (B.F.); (M.S.); (W.C.); (X.L.); (C.S.); (H.W.)
| | - Miaomiao Sun
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; (Y.X.); (J.Z.); (B.F.); (M.S.); (W.C.); (X.L.); (C.S.); (H.W.)
| | - Wenqian Cao
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; (Y.X.); (J.Z.); (B.F.); (M.S.); (W.C.); (X.L.); (C.S.); (H.W.)
| | - Xiaotian Liu
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; (Y.X.); (J.Z.); (B.F.); (M.S.); (W.C.); (X.L.); (C.S.); (H.W.)
| | - Yunpeng Gai
- School of Grassland Science, Beijing Forestry University, Beijing 100083, China;
| | - Chenjia Shen
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; (Y.X.); (J.Z.); (B.F.); (M.S.); (W.C.); (X.L.); (C.S.); (H.W.)
| | - Huizhong Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; (Y.X.); (J.Z.); (B.F.); (M.S.); (W.C.); (X.L.); (C.S.); (H.W.)
| | - Mingshuang Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; (Y.X.); (J.Z.); (B.F.); (M.S.); (W.C.); (X.L.); (C.S.); (H.W.)
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3
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Knight NL, Adhikari KC, Dodhia KN, Mair WJ, Lopez-Ruiz FJ. Workflows for detecting fungicide resistance in net form and spot form net blotch pathogens. PEST MANAGEMENT SCIENCE 2024; 80:2131-2140. [PMID: 38145910 DOI: 10.1002/ps.7951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 12/19/2023] [Accepted: 12/26/2023] [Indexed: 12/27/2023]
Abstract
BACKGROUND Fungicide resistance in Pyrenophora teres f. maculata and P. teres f. teres has become an important disease management issue. Control of the associated barley foliar diseases, spot form and net form net blotch, respectively, relies on three major groups of fungicides, demethylation inhibitors (DMIs), succinate dehydrogenase inhibitors (SDHIs) and quinone outside inhibitors (QoIs). However, resistance has been reported for the DMI and SDHI fungicides in Australia. To enhance detection of different resistance levels, phenotyping and genotyping workflows were designed. RESULTS The phenotyping workflow generated cultures directly from lesions and compared growth on discriminatory doses of tebuconazole (DMI) and fluxapyroxad (SDHI). Genotyping real-time polymerase chain reaction (PCR) assays were based on alleles associated with sensitivity or resistance to the DMI and SDHI fungicides. These workflows were applied to spot form and net form net blotch collections from 2019 consisting predominantly of P. teres f. teres from South Australia and P. teres f. maculata from Western Australia. For South Australia the Cyp51A L489-3 and SdhC-R134 alleles, associated with resistance to tebuconazole and fluxapyroxad, respectively, were the most prevalent. These alleles were frequently found in single isolates with dual resistance. This study also reports the first detection of a 134 base pair insertion located at position-66 (PtTi-6) in the Cyp51A promoter of P. teres f. maculata from South Australia. For Western Australia, the PtTi-1 insertion was the most common allele associated with resistance to tebuconazole. CONCLUSION The workflow and PCR assays designed in this study have been demonstrated to efficiently screen P. teres collections for both phenotypic and genetic resistance to DMI and SDHI fungicides. The distribution of reduced sensitivity and resistance to DMI and SDHI fungicides varied between regions in south-western Australia, suggesting the emergence of resistance was impacted by both local pathogen populations and disease management programmes. The knowledge of fungicide resistance in regional P. teres collections will be important for informing appropriate management strategies. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Noel L Knight
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, Australia
| | - Kul C Adhikari
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, Australia
| | - Kejal N Dodhia
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, Australia
| | - Wesley J Mair
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, Australia
| | - Francisco J Lopez-Ruiz
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, Australia
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Pütsepp R, Mäe A, Põllumaa L, Andresen L, Kiiker R. Fungicide Sensitivity Profile of Pyrenophora teres f. teres in Field Population. J Fungi (Basel) 2024; 10:260. [PMID: 38667932 PMCID: PMC11051325 DOI: 10.3390/jof10040260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/14/2024] [Accepted: 03/27/2024] [Indexed: 04/28/2024] Open
Abstract
Pyrenophora teres f. teres (Ptt) is a severe pathogen to spring barley in Northern Europe. Ptt with relevant mutations in fungicide target proteins, sterol 14α-demethylase (CYP51A), cytochrome b (Cyt b), and succinate dehydrogenase (SDH) would put efficient disease control at risk. In the growing seasons of 2021 and 2022, 193 Ptt isolates from Estonia were analysed. In this study, mutation detection and in vitro fungicide sensitivity assays of single-spore isolates were carried out. Reduced sensitivity phenotype to mefentrifluconazole was evident in Ptt isolates with a F489L mutation in CYP51A or with 129 bp insert in the Cyp51A gene-promoter region. However, sensitivity to a prothioconazole-desthio remained high regardless of these molecular changes. The Ptt population was mostly sensitive to bixafen, fluxapyroxad, pyraclostrobin, and azoxystrobin. The sensitivity of fluxapyroxad and bixafen has been affected by two mutations, C-S135R and D-H134R, found in SDH subunits. The F129L mutation in Cyt b influenced azoxystrobin but not pyraclostrobin sensitivity. In total, 30 isolates from five fields had relevant mutations in three target protein genes simultaneously. Most of these isolates had a reduced sensitivity phenotype to mefentrifluconazole, fluxapyroxad, and azoxystrobin, while sensitivity to other tested fungicides remained high. Furthermore, possible sexual reproduction may enhance the pathogen's fitness and help it adapt to fungicides.
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Affiliation(s)
| | | | | | | | - Riinu Kiiker
- Centre of Estonian Rural Research and Knowledge, 48309 Jõgeva Alevik, Estonia; (R.P.)
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Helps J, Lopez-Ruiz F, Zerihun A, van den Bosch F. Do Growers Using Solo Fungicides Affect the Durability of Disease Control of Growers Using Mixtures and Alternations? The Case of Spot-Form Net Blotch in Western Australia. PHYTOPATHOLOGY 2024; 114:590-602. [PMID: 38079394 DOI: 10.1094/phyto-02-23-0050-r] [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: 03/13/2024]
Abstract
Growers often use alternations or mixtures of fungicides to slow down the development of resistance to fungicides. However, within a landscape, some growers will implement such resistance management methods, whereas others do not, and may even apply solo components of the resistance management program. We investigated whether growers using solo components of resistant management programs affect the durability of disease control in fields of those who implement fungicide resistance management. We developed a spatially implicit semidiscrete epidemiological model for the development of fungicide resistance. The model simulates the development of epidemics of spot-form net blotch disease, caused by the pathogen Pyrenophora teres f. maculata. The landscape comprises three types of fields, grouped according to their treatment program, with spore dispersal between fields early in the cropping season. In one field type, a fungicide resistance management method is implemented, whereas in the two others, it is not, with one of these field types using a component of the fungicide resistance management program. The output of the model suggests that the use of component fungicides does affect the durability of disease control for growers using resistance management programs. The magnitude of the effect depends on the characteristics of the pathosystem, the degree of inoculum mixing between fields, and the resistance management program being used. Additionally, although increasing the amount of the solo component in the landscape generally decreases the lifespan within which the resistance management program provides effective control, situations exist where the lifespan may be minimized at intermediate levels of the solo component fungicide. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Joe Helps
- Rothamsted Research, Harpenden, AL5 2JQ, U.K
| | - Francisco Lopez-Ruiz
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA 6845, Australia
| | - Ayalsew Zerihun
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA 6845, Australia
| | - Frank van den Bosch
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA 6845, Australia
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Wang J, Shi H, Lu A. Design, Synthesis, and Antifungal/Anti-Oomycete Activities of Novel 1,2,4-Triazole Derivatives Containing Carboxamide Fragments. J Fungi (Basel) 2024; 10:160. [PMID: 38392832 PMCID: PMC10890616 DOI: 10.3390/jof10020160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/05/2024] [Accepted: 02/17/2024] [Indexed: 02/25/2024] Open
Abstract
Plant diseases caused by pathogenic fungi or oomycetes seriously affect crop growth and the quality and yield of products. A series of novel 1,2,4-triazole derivatives containing carboxamide fragments based on amide fragments widely used in fungicides and the commercialized mefentrifluconazole were designed and synthesized. Their antifungal activities were evaluated against seven kinds of phytopathogenic fungi/oomycete. Results showed that most compounds had similar or better antifungal activities compared to mefentrifluconazole's inhibitory activity against Physalospora piricola, especially compound 6h (92%), which possessed outstanding activity. Compound 6h (EC50 = 13.095 μg/mL) showed a better effect than that of mefentrifluconazole (EC50 = 39.516 μg/mL). Compound 5j (90%) displayed outstanding anti-oomycete activity against Phytophthora capsici, with an EC50 value of 17.362 μg/mL, far superior to that of mefentrifluconazole (EC50 = 75.433 μg/mL). The result of molecular docking showed that compounds 5j and 6h possessed a stronger affinity for 14α-demethylase (CYP51). This study provides a new approach to expanding the fungicidal spectrum of 1,2,4-triazole derivatives.
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Affiliation(s)
- Jiali Wang
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, China
| | - Haoran Shi
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, China
| | - Aidang Lu
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300401, China
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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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8
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Li G, Ru B, Zhang L, Li Y, Gao X, Peng Q, Miao J, Liu X. Mefentrifluconazole-Resistant Risk and Resistance-Related Point Mutation in FpCYP51B of Fusarium pseudograminearum. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:1516-1526. [PMID: 38194482 DOI: 10.1021/acs.jafc.3c08014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
Mefentrifluconazole, a triazole fungicide, exhibits remarkable efficacy in combating Fusarium spp. The mean EC50 value of mefentrifluconazole against 124 isolates of Fusarium pseudograminearum was determined to be 1.06 μg/mL in this study. Fungicide taming produced five mefentrifluconazole-resistant mutants with resistance factors ranging from 19.21 to 111.34. Compared to the original parental isolates, the fitness of three resistant mutants was much lower, while the remaining two mutants displayed enhanced survival fitness. There was evidence of positive cross-resistance between tebuconazole and mefentrifluconazole. Mefentrifluconazole resistance in F. pseudograminearum can be conferred by FpCYP51BL144F, which was identified in four mutants according to molecular docking and site-directed transformation experiments. Overexpression of FpCYP51s was also detected in the resistant mutants. In conclusion, mefentrifluconazole has a low-to-medium resistance risk in F. pseudograminearum, and the L144F mutation in FpCYP51B and the increased expression level of FpCYP51s may be responsible for mefentrifluconazole 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
| | - Binglu Ru
- 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
| | - 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
| | - Qin Peng
- 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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9
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Hodgson LM, Rakshit S, Lopez-Ruiz FJ, Gibberd MR, Thomas GJ, Zerihun A. Spatial Dependency in Stubble-Borne Pyrenophora teres f. teres and Influence of Sample Support Size on DNA Concentration and Fungicide Resistance Frequency. PHYTOPATHOLOGY 2024; 114:269-281. [PMID: 37505095 DOI: 10.1094/phyto-02-23-0062-r] [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: 07/29/2023]
Abstract
Fungicide resistance in foliar fungal pathogens is an increasing challenge to crop production. Yield impacts due to loss of fungicide efficacy may be reduced through effective surveillance and appropriate management intervention. For stubble-borne pathogens, off-season crop residues may be used to monitor fungicide resistance to inform pre-planting decisions; however, appropriate sampling strategies and support sizes for crop residues have not previously been considered. Here, we used Pyrenophora teres f. teres (Ptt) with resistance to demethylase inhibitor fungicides as a model system to assess spatial dependency and to compare the effects of different sampling strategies and support sizes on pathogen density (Ptt DNA concentration) and the frequency of fungicide resistance mutation. The results showed that sampling strategies (hand-picked versus raked) did not affect estimates of pathogen density or fungicide resistance frequency; however, sample variances were lower from raked samples. The effects of differing sample support size, as the size of the collection area (1.2, 8.6, or 60 m2), on fungicide resistance frequency were not evident (P > 0.05). However, measures of pathogen density increased with area size (P < 0.05); the 60 m2 area yielded the highest Ptt DNA concentration and produced the lowest number of pathogen-absent samples. Sample variances for pathogen density and fungicide resistance frequency were generally homogeneous between area sizes. The pattern of pathogen density was spatially independent; however, spatial dependency was identified for fungicide resistance frequency, with a range of 110 m, in one of the two fields surveyed. Collectively, the results inform designs for monitoring of fungicide resistance in stubble-borne pathogens.
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Affiliation(s)
- Leon M Hodgson
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Suman Rakshit
- Curtin Biometry and Agriculture Data Analytics, Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia
- School of Electrical Engineering, Computing and Mathematical Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Francisco J Lopez-Ruiz
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Mark R Gibberd
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Geoff J Thomas
- Department of Primary Industries and Regional Development, South Perth, WA 6151, Australia
| | - Ayalsew Zerihun
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
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10
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Dorigan AF, Moreira SI, da Silva Costa Guimarães S, Cruz-Magalhães V, Alves E. Target and non-target site mechanisms of fungicide resistance and their implications for the management of crop pathogens. PEST MANAGEMENT SCIENCE 2023; 79:4731-4753. [PMID: 37592727 DOI: 10.1002/ps.7726] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/14/2023] [Accepted: 08/18/2023] [Indexed: 08/19/2023]
Abstract
Fungicides are indispensable for high-quality crops, but the rapid emergence and evolution of fungicide resistance have become the most important issues in modern agriculture. Hence, the sustainability and profitability of agricultural production have been challenged due to the limited number of fungicide chemical classes. Resistance to site-specific fungicides has principally been linked to target and non-target site mechanisms. These mechanisms change the structure or expression level, affecting fungicide efficacy and resulting in different and varying resistance levels. This review provides background information about fungicide resistance mechanisms and their implications for developing anti-resistance strategies in plant pathogens. Here, our purpose was to review changes at the target and non-target sites of quinone outside inhibitor (QoI) fungicides, methyl-benzimidazole carbamate (MBC) fungicides, demethylation inhibitor (DMI) fungicides, and succinate dehydrogenase inhibitor (SDHI) fungicides and to evaluate if they may also be associated with a fitness cost on crop pathogen populations. The current knowledge suggests that understanding fungicide resistance mechanisms can facilitate resistance monitoring and assist in developing anti-resistance strategies and new fungicide molecules to help solve this issue. © 2023 Society of Chemical Industry.
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Affiliation(s)
| | | | | | | | - Eduardo Alves
- Department of Plant Pathology, Federal University of Lavras, Lavras, Brazil
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11
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Scanlan JL, Mitchell AC, Marcroft SJ, Forsyth LM, Idnurm A, Van de Wouw AP. Deep amplicon sequencing reveals extensive allelic diversity in the erg11/CYP51 promoter and allows multi-population DMI fungicide resistance monitoring in the canola pathogen Leptosphaeria maculans. Fungal Genet Biol 2023; 168:103814. [PMID: 37343617 DOI: 10.1016/j.fgb.2023.103814] [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: 02/16/2023] [Revised: 04/29/2023] [Accepted: 06/12/2023] [Indexed: 06/23/2023]
Abstract
Continued use of fungicides provides a strong selection pressure towards strains with mutations to render these chemicals less effective. Previous research has shown that resistance to the demethylation inhibitor (DMI) fungicides, which target ergosterol synthesis, in the canola pathogen Leptosphaeria maculans has emerged in Australia and Europe. The change in fungicide sensitivity of individual isolates was found to be due to DNA insertions into the promoter of the erg11/CYP51 DMI target gene. Whether or not these were the only types of mutations and how prevalent they were in Australian populations was explored in the current study. New isolates with reduced DMI sensitivity were obtained from screens on DMI-treated plants, revealing eight independent insertions in the erg11 promoter. A novel deep amplicon sequencing approach applied to populations of ascospores fired from stubble identified an additional undetected insertion allele and quantified the frequencies of all known insertions, suggesting that, at least in the samples processed, the combined frequency of resistant alleles is between 0.0376% and 32.6%. Combined insertion allele frequencies positively correlated with population-level measures of in planta resistance to four different DMI treatments. Additionally, there was no evidence for erg11 coding mutations playing a role in conferring resistance in Australian populations. This research provides a key method for assessing fungicide resistance frequency in stubble-borne populations of plant pathogens and a baseline from which additional surveillance can be conducted in L. maculans. Whether or not the observed resistance allele frequencies are associated with loss of effective disease control in the field remains to be established.
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Affiliation(s)
- Jack L Scanlan
- School of BioSciences, The University of Melbourne, VIC 3010, Australia
| | - Angela C Mitchell
- School of BioSciences, The University of Melbourne, VIC 3010, Australia
| | | | | | - Alexander Idnurm
- School of BioSciences, The University of Melbourne, VIC 3010, Australia
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12
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Liu Y, Del Rio Mendoza LE, Qi A, Lakshman D, Bhuiyan MZR, Wyatt N, Neubauer J, Bolton M, Khan MFR. Resistance to QoI and DMI Fungicides Does Not Reduce Virulence of C. beticola Isolates in North Central United States. PLANT DISEASE 2023; 107:2825-2829. [PMID: 36825317 DOI: 10.1094/pdis-11-21-2583-re] [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
Cercospora leaf spot (CLS) is a destructive disease limiting sugar beet production and is managed using resistant cultivars, crop rotation, and timely applications of effective fungicides. Since 2016, its causal agent, Cercospora beticola, has been reported to be resistant to quinone outside inhibitors (QoIs) and to have reduced sensitive to demethylation inhibitors (DMIs) in sugar beet growing areas in North Dakota and Minnesota. Isolates of C. beticola resistant to QoIs, DMIs, and both QoIs and DMIs were collected from fields in Foxhome, Minnesota, in 2017. Fitness of these resistant isolates was compared with that of QoI- and DMI-sensitive isolates in laboratory and greenhouse studies. In the lab, mycelial growth, spore production, and spore germination were measured. The results showed that resistant isolates had significantly less mycelial growth and spore production than sensitive isolates, while no significant difference in spore germination was detected. In the greenhouse, six leaf-stage sugar beets were inoculated with a spore suspension made from each resistant group and incubated in separate humidity chambers. CLS disease severity was evaluated visually at 7, 14, and 21 days after inoculation (DAI), and the areas under disease progress curve (AUDPC) were calculated. Resistant isolates had significantly smaller AUDPC but still caused as high disease severity as the sensitive ones at 21 DAI. Although QoI- and/or DMI-resistant isolates had a relatively slower disease development, they still caused high disease severity and need to be factored in disease management practices.
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Affiliation(s)
- Yangxi Liu
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108, U.S.A
| | | | - Aiming Qi
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield AL10 9AB, U.K
| | - Dilip Lakshman
- Sustainable Agricultural Systems Laboratory, USDA-ARS, Beltsville, MD 20705, U.S.A
| | - M Z R Bhuiyan
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108, U.S.A
| | | | | | | | - Mohamed F R Khan
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108, U.S.A
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13
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Achilonu CC, Gryzenhout M, Ghosh S, Marais GJ. In Vitro Evaluation of Azoxystrobin, Boscalid, Fentin-Hydroxide, Propiconazole, Pyraclostrobin Fungicides against Alternaria alternata Pathogen Isolated from Carya illinoinensis in South Africa. Microorganisms 2023; 11:1691. [PMID: 37512864 PMCID: PMC10384428 DOI: 10.3390/microorganisms11071691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 06/17/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
Black spot disease or Alternaria black spot (ABS) of pecan (Carya illinoinensis) in South Africa is caused by Alternaria alternata. This fungal pathogen impedes the development of pecan trees and leads to low yield in pecan nut production. The present study investigated the in vitro effect of six fungicides against the mycelial growth of A. alternata isolates from ABS symptoms. Fungicides tested include Tilt (propiconazole), Ortiva (azoxystrobin), AgTin (fentin hydroxide), and Bellis (boscalid + pyraclostrobin). All fungicides were applied in 3 concentrations (0.2, 1, and 5 μg mL-1). Tilt and Bumper 250 EC containing propiconazole active ingredient (demethylation Inhibitors) were the most effective and inhibited all mycelial growth from up to 6 days post-incubation. The other active ingredients (succinate dehydrogenase inhibitors, organotin compounds, and quinone outside inhibitors) showed 75-85% mycelial growth inhibition. The effective concentration to inhibit mycelial growth by 50% (EC50) was estimated for each isolate and fungicide. The overall mean EC50 values for each fungicide on the six isolates were 1.90 μg mL-1 (Tilt), 1.86 μg mL-1 (Ortiva), 1.53 μg mL-1 (AgTin), and 1.57 μg mL-1 for (Bellis). This initial screening suggested that propiconazole fungicide was the most effective for future field trials test and how these fungicides could be used in controlling ABS disease.
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Affiliation(s)
- Conrad Chibunna Achilonu
- Department of Plant Sciences, Division of Plant Pathology, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein 9300, Free State, South Africa
| | - Marieka Gryzenhout
- Department of Genetics, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein 9300, Free State, South Africa
| | - Soumya Ghosh
- Department of Genetics, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein 9300, Free State, South Africa
| | - Gert Johannes Marais
- Department of Plant Sciences, Division of Plant Pathology, Faculty of Natural and Agricultural Sciences, University of the Free State, Bloemfontein 9300, Free State, South Africa
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14
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Yang J, Wang S, Zhang Y, Chen Y, Zhou H, Zhang G. Identification, Culture Characteristics and Whole-Genome Analysis of Pestalotiopsis neglecta Causing Black Spot Blight of Pinus sylvestris var. mongolica. J Fungi (Basel) 2023; 9:jof9050564. [PMID: 37233276 DOI: 10.3390/jof9050564] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/11/2023] [Accepted: 05/11/2023] [Indexed: 05/27/2023] Open
Abstract
Black spot needle blight is a serious conifer disease of Pinus sylvestris var. mongolica occurring in Northeast China, which is usually caused by the plant pathogenic fungus Pestalotiopsis neglecta. From the diseased pine needles collected in Honghuaerji, the P. neglecta strain YJ-3 was isolated and identified as the phytopathogen, and its culture characteristics were studied. Then, we generated a highly contiguous 48.36-Mbp genome assembly (N50 = 6.62 Mbp) of the P. neglecta strain YJ-3 by combining the PacBio RS II Single Molecule Real Time (SMRT) and Illumina HiSeq X Ten sequencing platforms. The results showed that a total of 13,667 protein-coding genes were predicted and annotated using multiple bioinformatics databases. The genome assembly and annotation resource reported here will be useful for the study of fungal infection mechanisms and pathogen-host interaction.
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Affiliation(s)
- Jing Yang
- College of Forestry, Guizhou University, Huaxi District, Guiyang 550025, China
| | - Shuren Wang
- Heilongjiang Province Key Laboratory of Forest Protection, School of Forest, Northeast Forestry University, Hexing Road 26, Xiangfang District, Harbin 150040, China
| | - Yundi Zhang
- Heilongjiang Province Key Laboratory of Forest Protection, School of Forest, Northeast Forestry University, Hexing Road 26, Xiangfang District, Harbin 150040, China
| | - Yunze Chen
- School of Biological Sciences, Guizhou Education University, Wudang District, Guiyang 550018, China
| | - Heying Zhou
- College of Forestry, Guizhou University, Huaxi District, Guiyang 550025, China
| | - Guocai Zhang
- Heilongjiang Province Key Laboratory of Forest Protection, School of Forest, Northeast Forestry University, Hexing Road 26, Xiangfang District, Harbin 150040, China
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15
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Sautua FJ, Carmona MA. SDHI resistance in Pyrenophora teres f teres and molecular detection of novel double mutations in sdh genes conferring high resistance. PEST MANAGEMENT SCIENCE 2023. [PMID: 37103894 DOI: 10.1002/ps.7517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 03/09/2023] [Accepted: 04/22/2023] [Indexed: 05/14/2023]
Abstract
BACKGROUND Net blotch (NB), caused by Pyrenophora teres f. teres (Ptt), is an important disease of barley worldwide. NB control is commonly achieved through the use of fungicide mixtures including strobilurins, triazoles and carboxamides. Succinate dehydrogenase inhibitors (SDHI) are important components of fungicide management programs of barley diseases. However, during the last growing seasons in Argentina, barley fields sprayed with mixtures containing SDHI fungicides have shown failures in NB control. Here, we report the isolation and characterization of Argentine Ptt strains resistant to SDHI fungicides. RESULTS Compared against a sensitive (wild-type) reference strain collected in 2008, all 21 Ptt isolates collected in 2021 exhibited resistance to pydiflumetofen and fluxapyroxad both in vitro and in vivo. Concordantly, all of them presented target-site mutations in any of the sdhB, sdhC and sdhD genes. Although the mutations detected have been previously reported in other parts of the world, this study documents for the first time the occurrence of double mutations in the same Ptt isolate. Specifically, the double mutation sdhC-N75S + sdhD-D145G confers high resistance to SDHI fungicides, while the double mutations sdhB-H277Y + sdhC-N75S and sdhB-H277Y + sdhC-H134R confer moderate levels of resistance in Ptt. CONCLUSIONS SDHI-resistance in Argentine Ptt populations is expected to increase. These findings emphasize the urgent need to perform a wider survey and a more frequent monitoring of SDHI sensitivity of Ptt populations and to develop and implement effective antiresistance tactics. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Francisco José Sautua
- Facultad de Agronomía-Cátedra de Fitopatología, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marcelo Aníbal Carmona
- Facultad de Agronomía-Cátedra de Fitopatología, Universidad de Buenos Aires, Buenos Aires, Argentina
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16
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Wei J, Guo X, Jiang J, Qian L, Xu J, Che Z, Huang X, Liu S. Resistance risk assessment of Fusarium pseudograminearum from wheat to prothioconazole. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 191:105346. [PMID: 36963928 DOI: 10.1016/j.pestbp.2023.105346] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/13/2023] [Accepted: 01/21/2023] [Indexed: 06/18/2023]
Abstract
Fusarium crown rot (FCR), primarily caused by Fusarium pseudograminearum, poses significant threats to cereal crops worldwide. Prothioconazole is a demethylation inhibitor (DMI) fungicide used to control FCR. However, the risk of resistance in F. pseudograminearum to prothioconazole has not yet been evaluated. In this study, the sensitivity of a total of 255 F. pseudograminearum strains obtained from Henan Province, China to prothioconazole were determined by the mycelial growth inhibition. The results showed that the effective concentration to 50% growth inhibition (EC50) of these strains ranged from 0.4228 μg/mL to 2.5284 μg/mL, with a mean EC50 value of 1.0692 ± 0.4527 μg/mL (mean ± SD). Thirty prothioconazole-resistant mutants were obtained out of six selected sensitive parental strains by means of fungicide taming. The resistant mutants exhibited defects in vegetative growth, conidia production, and pathogenicity on wheat seedlings compared to their parental strains. Under ion, cell wall, and temperature stress conditions but not osmotic stress, all the mutants exhibited decreased growth rates compared with their parental strains, which was consistent with the control treatment. Cross-resistance test showed that there was a cross-resistance relationship between prothioconazole and four DMI fungicides, including prochloraz, metconazole, tebuconazole and hexaconazole, but no cross-resistance was observed between prothioconazole and carbendazim, phenamacril, fludioxonil, or azoxystrobin. Although no site mutation occurred on Cyp51a and Cyp51b genes, the constitutive expression level of the Cyp51a gene was significantly increased in all mutants. After being treated with prothioconazole, the Cyp51a and Cyp51b genes were significantly increased in both the resistant mutants and their parents. These results suggested that the resistance to prothioconazole of the mutants may be attributed to the changes of the relative expression level of Cyp51a and Cyp51b genes. Taken together, these results could provide a theoretical basis for the scientific use of prothioconazole in the field and fungicide resistance management strategies.
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Affiliation(s)
- Jiangqiao Wei
- Department of Plant Protection, College of Horticulture and Plant Protection, Henan University of Science and Technology, Luoyang 471023, China
| | - Xuhao Guo
- Department of Plant Protection, College of Horticulture and Plant Protection, Henan University of Science and Technology, Luoyang 471023, China
| | - Jia Jiang
- Department of Plant Protection, College of Horticulture and Plant Protection, Henan University of Science and Technology, Luoyang 471023, China
| | - Le Qian
- Department of Plant Protection, College of Horticulture and Plant Protection, Henan University of Science and Technology, Luoyang 471023, China
| | - Jianqiang Xu
- Department of Plant Protection, College of Horticulture and Plant Protection, Henan University of Science and Technology, Luoyang 471023, China
| | - Zhiping Che
- Department of Plant Protection, College of Horticulture and Plant Protection, Henan University of Science and Technology, Luoyang 471023, China
| | - Xiaobo Huang
- Department of Plant Protection, College of Horticulture and Plant Protection, Henan University of Science and Technology, Luoyang 471023, China
| | - Shengming Liu
- Department of Plant Protection, College of Horticulture and Plant Protection, Henan University of Science and Technology, Luoyang 471023, China.
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17
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Hodgson LM, Cox BA, Lopez-Ruiz FJ, Gibberd MR, Thomas GJ, Zerihun A. Optimized Sample Processing Pipeline for PCR-Based Fungicide Resistance Quantification of Stubble-Borne Fungal Pathogens. PHYTOPATHOLOGY 2023; 113:321-333. [PMID: 36075052 DOI: 10.1094/phyto-07-22-0239-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Globally, yield losses associated with failed crop protection due to fungicide-resistant pathogens present an increasing problem. For stubble-borne pathogens, assessment of crop residues during the off-season could provide early fungicide resistance quantification for informed management decisions to mitigate yield losses. However, stubble assessment is hampered by assay inhibitors that are derived from decaying organic matter. To overcome assay inhibition from weathered stubble samples, we used a systems approach to quantify the frequency of resistance to demethylase inhibitor fungicides of the barley pathogen Pyrenophora teres f. teres. The system canvassed (i) 10 ball-milling conditions; (ii) four DNA extraction methodologies; and (iii) three column purification techniques for the provision of sufficient yield, quality, and purity of fungal DNA for a PCR-based fungicide resistance assay. Results show that DNA quantity and purity differed within each of the above three categories, with the optimized pipeline being (i) ball-milling samples in a 50-ml stainless steel canister for 5 min using a 20-mm ball at 30 revolutions s-1; (ii) a modified Brandfass method (extracted 64% more DNA than other methods assessed); and (iii) use of silica resin columns for the highest DNA concentration with optimal DNA purity. The chip-digital PCR assay, which quantified fungicide resistance from field samples, was unaffected by the DNA extraction method or purification technique, provided that thresholds of template quantity and purity were satisfied. In summary, this study has developed molecular pipeline options for pathogen fungicide resistance quantification from cereal stubbles, which can guide management for improved crop protection outcomes.
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Affiliation(s)
- Leon M Hodgson
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Belinda A Cox
- School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Francisco J Lopez-Ruiz
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Mark R Gibberd
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
| | - Geoff J Thomas
- Department of Primary Industries and Regional Development, South Perth, WA 6151, Australia
| | - Ayalsew Zerihun
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, WA 6102, Australia
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18
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Li F, Ebihara A, Sakahara Y, Matsumoto S, Ueno R, Bao W, Kimura M, Fuji SI, Shimizu M, Kageyama K, Suga H. Synergistic effect of amino acid substitutions in CYP51B for prochloraz resistance in Fusarium fujikuroi. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 189:105291. [PMID: 36549812 DOI: 10.1016/j.pestbp.2022.105291] [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: 09/20/2022] [Revised: 11/08/2022] [Accepted: 11/10/2022] [Indexed: 06/17/2023]
Abstract
Prochloraz has been used to control Fusarium fujikuroi, the causative pathogen of rice bakanae disease. Linkage analysis of FfCYP51 genes in the progenies obtained from crossing prochloraz moderately resistant and sensitive strains suggested that the FfCYP51B gene is involved in prochloraz resistance. Sequence comparison revealed that the prochloraz-resistant strain had an F511S or S312T/F511S substitution in FfCYP51B compared with the sensitive strains. The contribution of the S312T and F511S substitutions in FfCYP51B to prochloraz resistance was investigated by creating S/F-, T/F-, or T/S- types at 312/511 codons from the S/S-type, which is a natural moderately resistant strain, using a gene-editing technique. T/S exhibited the highest prochloraz resistance, followed by S/S-, T/F-, and S/F-types. These results indicated that the S312T and F511S substitutions in FfCYP51B had a synergistic effect on prochloraz resistance in F. fujikuroi.
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Affiliation(s)
- FangJing Li
- The United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Akio Ebihara
- Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Yuri Sakahara
- Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Sarara Matsumoto
- Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Reina Ueno
- Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - WanXue Bao
- Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Makoto Kimura
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Shin-Ichi Fuji
- Faculty of Bioresource Sciences, Akita Prefectural University, 241-438 Kaidobata-Nishi Nakano Shimoshinjo, Akita 010-0195, Japan
| | - Masafumi Shimizu
- Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Koji Kageyama
- River Basin Research Center, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Haruhisa Suga
- Institute for Glyco-core Research (iGCORE), Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan..
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19
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Wang C, Xu L, Liang X, Zhang Y, Zheng H, Chen J, Yang Y. Biochemical and Molecular Characterization of Prochloraz Resistance in Lasiodiplodia theobromae Field Isolates. PLANT DISEASE 2023; 107:177-187. [PMID: 35640950 DOI: 10.1094/pdis-10-21-2316-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Stem-end rot (SER), caused by Lasiodiplodia theobromae, is one of the most critical diseases of mango in China. The demethylation inhibitor fungicide prochloraz has been widely used in China to control mango diseases. Isolates (n = 139) of L. theobromae were collected in 2019 from six mango-producing regions in Hainan Province, China. The fungicide sensitivity of L. theobromae isolates to prochloraz revealed that the EC50 (50% effective concentration) values ranged from 0.0006 to 16.4131 µg/ml. In total, 21 of the 139 isolates were categorized as resistant to prochloraz. The resistant isolates sprayed with prochloraz could not be effectively controlled in detached fruit. The mycelial growth, conidia germination, and ability to grow at temperatures ranging from 12 to 35°C of resistant isolates decreased, suggesting fitness penalties. The experiment showed that, after treatment with prochloraz at 10 µg/ml, the content of ergosterol in the mycelia of the sensitive isolate decreased by 80.23%, whereas the resistant strain decreased by only 57.52%. The damage to membranes in the sensitive isolates was more serious than for resistant isolates. The target gene CYP51 and the ATP-binding cassette (ABC) subfamily ABCG gene were cloned but no mutation was found. When treated with prochloraz, the expression of CYP51 and ABCG in resistant isolates was significantly higher than in the sensitive isolates. Thus, induced expression of its target gene combined with the induction of expression drug efflux transporters appeared to mediate the prochloraz resistance of L. theobromae.
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Affiliation(s)
- Chenguang Wang
- College of Plant Protection, Hainan University/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou 570228, China
| | - Luxi Xu
- College of Plant Protection, Hainan University/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou 570228, China
| | - Xiaoyu Liang
- College of Plant Protection, Hainan University/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou 570228, China
| | - Yu Zhang
- College of Plant Protection, Hainan University/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou 570228, China
| | - HuiYing Zheng
- College of Plant Protection, Hainan University/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou 570228, China
| | - JunLiu Chen
- College of Plant Protection, Hainan University/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou 570228, China
| | - Ye Yang
- College of Plant Protection, Hainan University/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou 570228, China
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20
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Harper LA, Paton S, Hall B, McKay S, Oliver RP, Lopez-Ruiz FJ. Fungicide resistance characterized across seven modes of action in Botrytis cinerea isolated from Australian vineyards. PEST MANAGEMENT SCIENCE 2022; 78:1326-1340. [PMID: 34854539 DOI: 10.1002/ps.6749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 11/04/2021] [Accepted: 12/02/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Botrytis bunch rot, caused by Botrytis cinerea, is an economically important disease of grapes in Australia and across grape-growing regions worldwide. Control of this disease relies on canopy management and the application of fungicides. Fungicide application can lead to the selection of resistant B. cinerea populations, which has an adverse effect on the management of the disease. Characterizing the distribution and severity of resistant B. cinerea populations is needed to inform resistance management strategies. RESULTS In this study, 724 isolates were sampled from 76 Australian vineyards during 2013-2016 and were screened against seven fungicides with different modes of action (MOAs). The resistance frequencies for azoxystrobin, boscalid, fenhexamid, fludioxonil, iprodione, pyrimethanil and tebuconazole were 5%, 2.8%, 2.1%, 6.2%, 11.6%, 7.7% and 2.9%, respectively. Nearly half of the resistant isolates (43.8%) were resistant to more than one of the fungicides tested. The frequency of vineyards with at least one isolate simultaneously resistant to one, two, three, four or five fungicides was 19.7%, 7.9%, 6.6%, 10.5% and 2.6%. Resistance was associated with previously published genotypes in CytB (G143A), SdhB (H272R/Y), Erg27 (F412S), Mrr1 (D354Y), Bos1 (I365S, N373S + Q369P, I365S + D757N) and Pos5 (V273I, P319A, L412F/V). Novel genotypes were also described in Mrr1 (S611N, D616G), Pos5 (V273L) and Cyp51 (P347S). Expression analysis was used to characterize fludioxonil-resistant isolates exhibiting overexpression (6.3-9.6-fold) of the ABC transporter gene AtrB (MDR1 phenotype). CONCLUSION Resistance frequencies were lower when compared to most previously published surveys of B. cinerea resistance in grape and other crops. Nevertheless, continued monitoring of critical MOAs used in Australian vineyards is recommended. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Lincoln A Harper
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, Australia
| | | | - Barbara Hall
- South Australian Research and Development Institute, Plant Health and Biosecurity, Urrbrae, Australia
| | - Suzanne McKay
- South Australian Research and Development Institute, Plant Health and Biosecurity, Urrbrae, Australia
| | - Richard P Oliver
- School of Molecular and Life Sciences, Curtin University, Bentley, Australia
| | - Francisco J Lopez-Ruiz
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Bentley, Australia
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21
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Management of Pyrenophora teres f. teres, the Causal Agent of Net Form Net Blotch of Barley, in A Two-Year Field Experiment in Central Italy. Pathogens 2022; 11:pathogens11030291. [PMID: 35335615 PMCID: PMC8954409 DOI: 10.3390/pathogens11030291] [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: 01/28/2022] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 12/10/2022] Open
Abstract
Pyrenophora teres is the causal agent of barley net blotch (NB), a disease that can be found in two different forms: net form (NFNB), caused by P. teres f. teres, and spot form (SFNB), caused by P. teres f. maculata. A two-year field experiment was carried out to evaluate the response to NB of six different barley cultivars for malt or feed/food production. In addition, the efficacy of several recently developed foliar fungicides with different modes of action (SDHI, DMI, and QoI) towards the disease was examined. After NB leaf symptom evaluation, the identification of P. teres forms was performed. Grain yield was determined, and pathogen biomass was quantified in the grain by qPCR. In the two experimental years characterized by different climatic conditions, only P. teres f. teres was detected. The tested cultivars showed different levels of NFNB susceptibility. In particular, the two-row cultivars for malt production showed the highest disease incidence. All applied fungicides exhibited a high efficacy in reducing disease symptoms on leaves and pathogen accumulation in grains. In fact, high levels of fungal biomass were detected only in the grain of the untreated malting barley cultivars. For some cultivars, grain yield was positively influenced by the application of fungicides.
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22
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Molecular characterization and overexpression of the difenoconazole resistance gene CYP51 in Lasiodiplodia theobromae field isolates. Sci Rep 2021; 11:24299. [PMID: 34934102 PMCID: PMC8692403 DOI: 10.1038/s41598-021-03601-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 11/30/2021] [Indexed: 11/22/2022] Open
Abstract
Stem-end rot (SER) caused by Lasiodiplodia theobromae is an important disease of mango in China. Demethylation inhibitor (DMI) fungicides are widely used for disease control in mango orchards. The baseline sensitivity to difenoconazole of 138 L. theobromae isolates collected from mango in the field in 2019 was established by the mycelial growth rate method. The cross-resistance to six site-specific fungicides with different modes of action were investigated using 20 isolates randomly selected. The possible mechanism for L. theobromae resistance to difenoconazole was preliminarily determined through gene sequence alignment and quantitative real-time PCR analysis. The results showed that the EC50 values of 138 L. theobromae isolates to difenoconazole ranged from 0.01 to 13.72 µg/mL. The frequency of difenoconazole sensitivity formed a normal distribution curve when the outliers were excluded. Difenoconazole showed positive cross-resistance only with the DMI tebuconazole but not with non-DMI fungicides carbendazim, pyraclostrobin, fludioxonil, bromothalonil, or iprodione. Some multifungicide-resistant isolates of L. theobromae were found. Two amino acid substitutions (E209k and G207A) were found in the CYP51 protein, but they were unlikely to be related to the resistance phenotype. There was no alteration in the promoter region of the CYP51 gene. However, difenoconazole significantly increased the expression of the CYP51 gene in the resistant isolates compared to the susceptible isolates. These results are vital to develop effective mango disease management strategies to avoid the development of further resistance.
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Santos RF, Amorim L, Wood AKM, Bibiano LBJ, Fraaije BA. Lack of an Intron in Cytochrome b and Overexpression of Sterol 14α-Demethylase Indicate a Potential Risk for QoI and DMI Resistance Development in Neophysopella spp. on Grapes. PHYTOPATHOLOGY 2021; 111:1726-1734. [PMID: 33703921 DOI: 10.1094/phyto-11-20-0514-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
Asian grapevine leaf rust, caused by Neophysopella meliosmae-myrianthae and N. tropicalis, is often controlled by quinone outside inhibitor (QoI) and demethylation inhibitor (DMI) fungicides in Brazil. Here, we evaluated the sensitivity of 55 Neophysopella spp. isolates to pyraclostrobin (QoI) and tebuconazole (DMI). To elucidate the resistance mechanisms, we analyzed the sequences of the cytochrome b (CYTB) and cytochrome P450 sterol 14α-demethylase (CYP51) target proteins of QoI and DMI fungicides, respectively. The CYP51 expression levels were also determined in a selection of isolates. In leaf disc assays, the mean 50% effective concentration (EC50) value for pyraclostrobin was about 0.040 µg/ml for both species. CYTB sequences were identical among all 55 isolates, which did not contain an intron immediately after codon 143. No amino acid substitution was identified at codons 129, 137, and 143. The mean EC50 value for tebuconazole was 0.62 µg/ml for N. tropicalis and 0.46 µg/ml for N. meliosmae-myrianthae, and no CYP51 sequence variation was identified among isolates of the same species. However, five N. meliosmae-myrianthae isolates grew on leaf discs treated at 10 µg/ml tebuconazole, and these were further exposed to tebuconazole selection pressure. Tebuconazole-adapted laboratory isolates of N. meliosmae-myrianthae showed an eight- to 25-fold increase in resistance after four rounds of selection that was not associated with CYP51 target alterations. In comparison with sensitive isolates, CYP51 expression was induced in the presence of tebuconazole in three out of four tebuconazole-adapted isolates tested. These results suggest a potential risk for QoI and DMI resistance development in Neophysopella spp.
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Affiliation(s)
- Ricardo F Santos
- Department of Plant Pathology and Nematology, "Luiz de Queiroz" College of Agriculture, University of São Paulo, Piracicaba, São Paulo, 13418-900, Brazil
| | - Lilian Amorim
- Department of Plant Pathology and Nematology, "Luiz de Queiroz" College of Agriculture, University of São Paulo, Piracicaba, São Paulo, 13418-900, Brazil
| | - Ana K M Wood
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom
| | - Líllian B J Bibiano
- Department of Plant Pathology and Nematology, "Luiz de Queiroz" College of Agriculture, University of São Paulo, Piracicaba, São Paulo, 13418-900, Brazil
| | - Bart A Fraaije
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom
- National Institute of Agricultural Botany, Cambridge, Cambridgeshire, CB3 0LE, United Kingdom
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24
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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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25
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Gañán-Betancur L, Peever TL, Amiri A. No Evidence of Resistance to Trifloxystrobin, Triflumizole, and Boscalid in Podosphaera leucotricha Isolates From U.S. Commercial Apple Orchards. PLANT DISEASE 2021; 105:2356-2365. [PMID: 33728959 DOI: 10.1094/pdis-12-20-2685-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Apple powdery mildew, caused by Podosphaera leucotricha, continues to be a challenge in commercial apple orchards in the U.S. Pacific Northwest and worldwide. In this study, P. leucotricha isolates were collected in 2018 and 2019 from two organic (baseline) and eight conventional (exposed) apple orchards in Washington, New York, and Virginia, and assessed for their sensitivity to trifloxystrobin (TRI, n = 232), triflumizole (TFZ, n = 217), and boscalid (BOS, n = 240) using a detached leaf assay. Effective concentrations inhibiting 50% growth (EC50) were not significantly different between baseline and exposed isolates, and ranged from 0.001 to 0.105, 0.09 to 6.31, and 0.05 to 2.18 µg/ml, for TRI, TFZ, and BOS, respectively. Reduction in sensitivity by factors of 105, 63, and 22 to TRI, TFZ, and BOS, respectively, were observed in some isolates, but all isolates were controlled by the commercial label rates of the three fungicides on detached leaves. Sequencing of the cytochrome b (cytb), cytochrome P450 sterol 14α-demethylase (CYP51), and the iron-sulfur protein subunit (SdhB) genes in isolates with high EC50 revealed no mutation previously reported to confer resistance to these fungicides in other fungi, and presence of a group I intron after codon 143 in the cytb gene. Significant (P < 0.001) moderate positive correlations (r = 0.38) observed between sensitivity to TRI and TFZ warrant continuous rotations of fungicides with different modes of action in conventional orchards. The established baseline sensitivities and the molecular markers will help in selecting discriminatory doses and bypassing the challenging in vivo testing for future sensitivity monitoring in P. leucotricha.
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Affiliation(s)
- Lederson Gañán-Betancur
- Department of Plant Pathology, Washington State University, Pullman, WA 99163
- Tree Fruit Research and Extension Center, Washington State University, Wenatchee, WA 98801
| | - Tobin L Peever
- Department of Plant Pathology, Washington State University, Pullman, WA 99163
| | - Achour Amiri
- Tree Fruit Research and Extension Center, Washington State University, Wenatchee, WA 98801
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26
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Cook NM, Chng S, Woodman TL, Warren R, Oliver RP, Saunders DG. High frequency of fungicide resistance-associated mutations in the wheat yellow rust pathogen Puccinia striiformis f. sp. tritici. PEST MANAGEMENT SCIENCE 2021; 77:3358-3371. [PMID: 33786966 DOI: 10.1002/ps.6380] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/23/2021] [Accepted: 03/31/2021] [Indexed: 05/14/2023]
Abstract
BACKGROUND Reliance on fungicides to manage disease creates selection pressure for the evolution of resistance in fungal and oomycete pathogens. Rust fungi (Pucciniales) are major pathogens of cereals and other crops and have been classified as low-risk for developing resistance to fungicides; no case of field failure of fungicides in a cereal rust disease has yet been recorded. Recently, the Asian soybean rust pathogen, Phakopsora pachyrhizi evolved resistance to several fungicide classes, prompting us to screen a large sample of the globally widespread wheat yellow rust pathogen, Puccinia striiformis f. sp. tritici (Pst), for mutations associated with fungicide resistance. RESULTS We evaluated 363 Pst isolates from Europe, the USA, Ethiopia, Chile, China and New Zealand for mutations in the target genes of demethylase inhibitor (DMI; Cyp51) and succinate dehydrogenase inhibitor (SDHI; SdhB, SdhC and SdhD) fungicides. A high proportion of Pst isolates carrying a Y134F DMI resistance-associated substitution in the Cyp51 gene was found among those from China and New Zealand. A set of geographically diverse Pst isolates was also found to display a substitution in SdhC (I85V) that is homologous to that reported recently in P. pachyrhizi and linked to SDHI resistance. CONCLUSION The identification of resistance-associated alleles confirms that cereal rusts are not immune to fungicide resistance and that selection for resistance evolution is operating at high levels in certain locations. It highlights the need to adopt fungicide resistance management practices and to monitor cereal rust species for development of resistance. © 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)
- Nicola M Cook
- John Innes Centre, Norwich Research Park, Norwich, UK
| | - Soonie Chng
- The New Zealand Institute for Plant & Food Research Limited, Lincoln, New Zealand
| | | | - Rachael Warren
- The New Zealand Institute for Plant & Food Research Limited, Lincoln, New Zealand
| | - Richard P Oliver
- Molecular and Life Sciences, Curtin University, Bentley, Australia
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27
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Backes A, Guerriero G, Ait Barka E, Jacquard C. Pyrenophora teres: Taxonomy, Morphology, Interaction With Barley, and Mode of Control. FRONTIERS IN PLANT SCIENCE 2021; 12:614951. [PMID: 33889162 PMCID: PMC8055952 DOI: 10.3389/fpls.2021.614951] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 03/08/2021] [Indexed: 05/27/2023]
Abstract
Net blotch, induced by the ascomycete Pyrenophora teres, has become among the most important disease of barley (Hordeum vulgare L.). Easily recognizable by brown reticulated stripes on the sensitive barley leaves, net blotch reduces the yield by up to 40% and decreases seed quality. The life cycle, the mode of dispersion and the development of the pathogen, allow a quick contamination of the host. Crop residues, seeds, and wild grass species are the inoculum sources to spread the disease. The interaction between the barley plant and the fungus is complex and involves physiological changes with the emergence of symptoms on barley and genetic changes including the modulation of different genes involved in the defense pathways. The genes of net blotch resistance have been identified and their localizations are distributed on seven barley chromosomes. Considering the importance of this disease, several management approaches have been performed to control net blotch. One of them is the use of beneficial bacteria colonizing the rhizosphere, collectively referred to as Plant Growth Promoting Rhizobacteria. Several studies have reported the protective role of these bacteria and their metabolites against potential pathogens. Based on the available data, we expose a comprehensive review of Pyrenophora teres including its morphology, interaction with the host plant and means of control.
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Affiliation(s)
- Aurélie Backes
- Unité de Recherche Résistance Induite et Bioprotection des Plantes, Université de Reims Champagne-Ardenne, Reims, France
| | - Gea Guerriero
- Environmental Research and Innovation (ERIN) Department, Luxembourg Institute of Science and Technology (LIST), Hautcharage, Luxembourg
| | - Essaid Ait Barka
- Unité de Recherche Résistance Induite et Bioprotection des Plantes, Université de Reims Champagne-Ardenne, Reims, France
| | - Cédric Jacquard
- Unité de Recherche Résistance Induite et Bioprotection des Plantes, Université de Reims Champagne-Ardenne, Reims, France
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28
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Muellender MM, Mahlein AK, Stammler G, Varrelmann M. Evidence for the association of target-site resistance in cyp51 with reduced DMI sensitivity in European Cercospora beticola field isolates. PEST MANAGEMENT SCIENCE 2021; 77:1765-1774. [PMID: 33236506 DOI: 10.1002/ps.6197] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 11/10/2020] [Accepted: 11/24/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Cercospora leaf spot caused by Cercospora beticola is the most relevant foliar disease in sugar beet cultivation. In the last decade a decreasing sensitivity of C. beticola towards demethylation inhibitors (DMIs) occurred. Different mechanisms mediating a reduced sensitivity towards DMIs have been identified in different plant pathogens to date, such as target site mutations, over-expression or active excretion of the fungicide. RESULTS A sequencing of the cytochrome P450-dependent sterol 14α-demethylase gene sequence (cyp51) of diverse C. beticola isolates collected in different European countries with reduced DMI sensitivity was performed in order to find a possible correlation of mutations with higher EC50 values. The amino acid alterations Y464S, L144F and I309T combined with L144F were found to be associated with a reduced sensitivity. Furthermore, mutations I387M, M145W and M145W with E460Q were found uniquely. Additionally, constitutive and fungicide triggered expression of cyp51 was assayed by means of RT-qPCR. A very strong induction of cyp51 mRNA expression in sensitive isolates suggests that the fungal cells upregulate expression to maintain ergosterol biosynthesis in DMI presence. The less intensive cyp51 induction in isolates with higher EC50 values underlines the possible correlation of the found target-site mutations with reduced sensitivity. CONCLUSION This study provides new results about possible alterations in the target gene mediating reduced sensitivity of C. beticola towards DMIs and hypothesized a fungicide induced over-expression of the target enzyme CYP51 as natural reaction of the fungus to fungicide application. © 2020 Society of Chemical Industry.
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29
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Rapid in situ quantification of the strobilurin resistance mutation G143A in the wheat pathogen Blumeria graminis f. sp. tritici. Sci Rep 2021; 11:4526. [PMID: 33633193 PMCID: PMC7907364 DOI: 10.1038/s41598-021-83981-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 02/08/2021] [Indexed: 11/25/2022] Open
Abstract
As the incidence of fungicide resistance in plant pathogens continues to increase, control of diseases and the management of resistance would be greatly aided by rapid diagnostic methods. Quantitative allele-specific PCR (ASqPCR) is an ideal technique for the in-field analysis of fungicide resistance as it can quantify the frequency of mutations in fungicide targets. We have applied this technique to the fungal pathogen Blumeria graminis f. sp. tritici (Bgt), the causal agent of wheat powdery mildew. In Australia, strobilurin-resistant Bgt was first discovered in 2016. Molecular analysis revealed a nucleotide transversion in the cytochrome b (cytb) gene in the cytochrome bc1 enzyme complex, resulting in a substitution of alanine for glycine at position 143 (G143A). We have developed an in-field ASqPCR assay that can quantify both the resistant (A143) and sensitive (G143) cytb alleles down to 1.67% in host and Bgt DNA mixtures, within 90 min of sample collection. The in situ analysis of samples collected during a survey in Tasmania revealed A143 frequencies ranging between 9–100%. Validation of the analysis with a newly developed laboratory based digital PCR assay found no significant differences between the two methods. We have successfully developed an in-field quantification method, for a strobilurin-resistant allele, by pairing the ASqPCR assay on a lightweight qPCR instrument with a quick DNA extraction method. The deployment of these type of methodologies in the field can contribute to the effective in-season management of fungicide resistance.
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30
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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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31
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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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32
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Tini F, Beccari G, Onofri A, Ciavatta E, Gardiner DM, Covarelli L. Fungicides may have differential efficacies towards the main causal agents of Fusarium head blight of wheat. PEST MANAGEMENT SCIENCE 2020; 76:3738-3748. [PMID: 32430980 DOI: 10.1002/ps.5923] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 05/06/2020] [Accepted: 05/20/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Fusarium head blight (FHB) is a complex disease of wheat and barley caused by several Fusarium species. In recent years, a variation in the composition of the FHB community has been observed in several wheat cultivation areas across the world. In detail, F. avenaceum and F. poae increased their frequencies, while, a lower F. graminearum and F. culmorum incidence was simultaneously observed. These shifts within the FHB complex might have been caused by different factors, including the selective pressure caused by fungicides used to control the disease in the field. Therefore, the present study was carried out to evaluate, both in in vitro experiments and in field trials, the activity of commonly used fungicides of wheat (tebuconazole, metconazole, prothioconazole and prochloraz) towards the above mentioned four Fusarium species. RESULTS A preliminary in vitro assay revealed that low concentrations of all tested fungicides caused the incomplete reduction of fungal development. Furthermore, F. poae and F. avenaceum showed, at the same time, a lower sensitivity to all tested fungicides. In field trials, all fungicides showed an activity against the four Fusarium species. However, F. avenaceum exhibited a reduced sensitivity to metconazole. The lower efficacy of metconazole towards F. avenaceum was also confirmed by an additional in vitro experiment on several F. avenaceum and F. graminearum different strains. CONCLUSION The selective pressure exerted by the extensive use of certain fungicides may influence population dynamics of Fusarium species due to their different sensitivity. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Francesco Tini
- Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia, Italy
| | - Giovanni Beccari
- Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia, Italy
| | - Andrea Onofri
- Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia, Italy
| | - Emiliano Ciavatta
- Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia, Italy
| | - Donald M Gardiner
- CSIRO Agriculture and Food, Queensland Bioscience Precinct, Brisbane, Queensland, Australia
| | - Lorenzo Covarelli
- Department of Agricultural, Food and Environmental Sciences, University of Perugia, Perugia, Italy
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33
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Lammari HI, Rehfus A, Stammler G, Benslimane H. Sensitivity of the Pyrenophora teres Population in Algeria to Quinone outside Inhibitors, Succinate Dehydrogenase Inhibitors and Demethylation Inhibitors. THE PLANT PATHOLOGY JOURNAL 2020; 36:218-230. [PMID: 32547338 PMCID: PMC7272849 DOI: 10.5423/ppj.oa.09.2019.0237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 03/25/2020] [Accepted: 04/21/2020] [Indexed: 05/27/2023]
Abstract
Net blotch of barley caused by Pyrenophora teres (Died.) Drechsler, is one of the most destructive diseases on barley in Algeria. It occurs in two forms: P. teres f. teres and P. teres f. maculata. A total of 212 isolates, obtained from 58 fields sampled in several barley growing areas, were assessed for fungicide sensitivity by target gene analysis. F129L and G137R mitochondrial cytochrome b substitution associated with quinone outside inhibitors (QoIs) resistance, and succinate dehydrogenase inhibitors (SDHIs) related mutations (B-H277, C-N75S, C-G79R, C-H134R, and C-S135R), were analyzed by pyrosequencing. In vitro sensitivity of 45 isolates, towards six fungicides belonging to three chemical groups (QoI, demethylase inhibitor, and SDHI) was tested by microtiter technique. Additionally, sensitivity towards three fungicides (azoxystrobin, fluxapyroxad, and epoxiconazole) was assessed in planta under glasshouse conditions. All tested isolates were QoI-sensitive and SDHI-sensitive, no mutation that confers resistance was identified. EC50 values showed that pyraclostrobin and azoxystrobin are the most efficient fungicides in vitro, whereas fluxapyroxad displayed the best disease inhibition in planta (81% inhibition at 1/9 of the full dose). The EC50 values recorded for each form of net blotch showed no significant difference in efficiency of QoI treatments and propiconazole on each form. However, in the case of fluxapyroxad, epoxiconazole and tebuconazole treatments, analysis showed significant differences in their efficiency. To our knowledge, this study is the first investigation related to mutations associated to QoI and SDHI fungicide resistance in Algerian P. teres population, as well as it is the first evaluation of the sensitivity of P. teres population towards these six fungicides.
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Affiliation(s)
- Hamama-Imène Lammari
- Phytopathology and Molecular Biology Laboratory, Department of Botany, National High College of Agriculture, Algiers, Algeria
| | | | - Gerd Stammler
- BASF SE, Agricultural Centre, 67117 Limburgerhof, Germany
| | - Hamida Benslimane
- Integrative Improvement of Crop Production Laboratory (Amélioration Intégrative des Productions Végétales), Department of Botany, National High College of Agriculture, Algiers C2711100, Algeria
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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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Yang Y, Marcoft SJ, Forsyth LM, Zhao J, Li Z, Van de Wouw AP, Idnurm A. Sterol Demethylation Inhibitor Fungicide Resistance in Leptosphaeria maculans is Caused by Modifications in the Regulatory Region of ERG11. PLANT DISEASE 2020; 104:1280-1290. [PMID: 32202465 DOI: 10.1094/pdis-10-19-2088-re] [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: 06/10/2023]
Abstract
Blackleg is a worldwide disease of canola (Brassica napus), caused by a complex of fungal species in the genus Leptosphaeria, that impacts canola production and seed quality. Demethylation inhibitor (DMI) fungicides that target sterol 14α-demethylase are an integral part of disease control. Here, we report six DMI-resistant isolates of Leptosphaeria maculans and two different types of genetic modification related to the resistance. Analysis of the regulatory region of the DMI target gene ERG11 (also known as CYP51) revealed a 275-bp insertion in two of the isolates and three long terminal repeat retrotransposons (5,263, 5,267, and 5,248 bp) inserted in the promoter region of three resistant isolates. Genetic approaches confirmed that these elements are responsible for DMI resistance in L. maculans and crosses show segregation consistent with a single locus. Reverse-transcription quantitative PCR assays demonstrated that the 275-bp insertion increases ERG11 gene expression, conferring DMI fungicide resistance both in vitro and in planta. Moreover, transformation of a susceptible isolate of L. maculans with ERG11 driven by a promoter containing the 275-bp insertion increased resistance to tebuconazole. A minimal shift of the values of concentration whereby 50% of the mycelial growth is inhibited in vitro was observed in resistant isolates containing long terminal repeat retrotransposons; nevertheless, these isolates were able to develop significant lesions on cotyledons from fungicide-treated seedlings. This is the first report of genetic modifications in L. maculans relating to DMI fungicide resistance.
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Affiliation(s)
- Yongqing Yang
- School of Life Sciences, Inner Mongolia University, Hohhot 010020, China
- School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia
- Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot 010031, China
| | - Stephen J Marcoft
- Marcroft Grains Pathology, Grains Innovation Park, Horsham, Victoria 3400, Australia
| | | | - Ji Zhao
- School of Life Sciences, Inner Mongolia University, Hohhot 010020, China
| | - Ziqin Li
- Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot 010031, China
| | - Angela P Van de Wouw
- School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alexander Idnurm
- School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia
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Phan HTT, Jones DAB, Rybak K, Dodhia KN, Lopez-Ruiz FJ, Valade R, Gout L, Lebrun MH, Brunner PC, Oliver RP, Tan KC. Low Amplitude Boom-and-Bust Cycles Define the Septoria Nodorum Blotch Interaction. FRONTIERS IN PLANT SCIENCE 2020; 10:1785. [PMID: 32082346 PMCID: PMC7005668 DOI: 10.3389/fpls.2019.01785] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 12/20/2019] [Indexed: 05/30/2023]
Abstract
INTRODUCTION Septoria nodorum blotch (SNB) is a complex fungal disease of wheat caused by the Dothideomycete fungal pathogen Parastagonospora nodorum. The fungus infects through the use of necrotrophic effectors (NEs) that cause necrosis on hosts carrying matching dominant susceptibility genes. The Western Australia (WA) wheatbelt is a SNB "hot spot" and experiences significant under favorable conditions. Consequently, SNB has been a major target for breeders in WA for many years. MATERIALS AND METHODS In this study, we assembled a panel of 155 WA P. nodorum isolates collected over a 44-year period and compared them to 23 isolates from France and the USA using 28 SSR loci. RESULTS The WA P. nodorum population was clustered into five groups with contrasting properties. 80% of the studied isolates were assigned to two core groups found throughout the collection location and time. The other three non-core groups that encompassed transient and emergent populations were found in restricted locations and time. Changes in group genotypes occurred during periods that coincided with the mass adoption of a single or a small group of widely planted wheat cultivars. When introduced, these cultivars had high scores for SNB resistance. However, the field resistance of these new cultivars often declined over subsequent seasons prompting their replacement with new, more resistant varieties. Pathogenicity assays showed that newly emerged isolates non-core are more pathogenic than old isolates. It is likely that the non-core groups were repeatedly selected for increased virulence on the contemporary popular cultivars. DISCUSSION The low level of genetic diversity within the non-core groups, difference in virulence, low abundance, and restriction to limited locations suggest that these populations more vulnerable to a population crash when the cultivar was replaced by one that was genetically different and more resistant. We characterize the observed pattern as a low-amplitude boom-and-bust cycle in contrast with the classical high amplitude boom-and-bust cycles seen for biotrophic pathogens where the contrast between resistance and susceptibility is typically much greater. Implications of the results are discussed relating to breeding strategies for more sustainable SNB resistance and more generally for pathogens with NEs.
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Affiliation(s)
- Huyen T. T. Phan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Darcy A. B. Jones
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Kasia Rybak
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Kejal N. Dodhia
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Francisco J. Lopez-Ruiz
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Romain Valade
- ARVALIS Institut du Végétal Avenue Lucien Brétignières, Bâtiment INRA Bioger, Thiverval-Grignon, France
| | - Lilian Gout
- UMR INRA Bioger Agro-ParisTech, Thiverval-Grignon, France
| | | | - Patrick C. Brunner
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, Zurich, Switzerland
| | - Richard P. Oliver
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
| | - Kar-Chun Tan
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
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He MH, Wang YP, Wu EJ, Shen LL, Yang LN, Wang T, Shang LP, Zhu W, Zhan J. Constraining Evolution of Alternaria alternata Resistance to a Demethylation Inhibitor (DMI) Fungicide Difenoconazole. Front Microbiol 2019; 10:1609. [PMID: 31354690 PMCID: PMC6636547 DOI: 10.3389/fmicb.2019.01609] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/27/2019] [Indexed: 02/02/2023] Open
Abstract
Evolution of fungicide resistance in plant pathogens is one of major concerns in sustainable plant disease management. In this study, the genetics and potential of developing resistance to a demethylation inhibitor (DMI) fungicide, difenoconazole, in the fungal pathogen Alternaria alternata was investigated using a comparative analysis of genetic variation in molecular (Single Sequence Repeats, SSR) and phenotypic (fungicide tolerance) markers. No difenoconazole resistance was found in the 215 A. alternata isolates sampled from seven different ecological zones in China despite the widespread use of the fungicide for more than 20 years. This result suggests that the risk of developing resistance to difenoconazole in A. alternata is low and we hypothesize that the low risk is likely caused by fitness penalties incurred by resistant mutants and the multiple mechanisms involving in developing resistance. Heritability and plasticity account for ∼24 and 3% of phenotypic variation, respectively, indicating that genetic adaptation by sequence variation plays a more important role in the evolution of difenoconazole resistance than physiological adaptation by altering gene expression. Constraining selection in the evolution of A. alternata resistance to difenoconazole was documented by different patterns of population differentiation and isolate-by-distance between SSR markers and difenoconazole tolerance. Though the risk of developing resistance is low, the findings of significant differences in difenoconazole tolerance among isolates and populations, and a skewing distribution toward higher tolerance suggests that a stepwise accumulation of tolerance to the fungicide might be occurring in the pathogen populations. As a consequence, dynamic management programs guided by evolutionary principles such as spatiotemporal rotations of fungicides with different modes of action are critical to prevent the continued accumulation of tolerance or the evolution of resistance to difenoconazole and other DMI fungicides.
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Affiliation(s)
- Meng-Han He
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Key Laboratory for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Yan-Ping Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Key Laboratory for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, China
| | - E-Jiao Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lin-Lin Shen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Li-Na Yang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Tian Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Li-Ping Shang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Wen Zhu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jiasui Zhan
- Key Laboratory 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 Agriculture and Forestry University, Fuzhou, China
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Sun B, Dong Y, Lei K, Wang J, Zhao L, Liu M. Design, synthesis and biological evaluation of amide-pyridine derivatives as novel dual-target (SE, CYP51) antifungal inhibitors. Bioorg Med Chem 2019; 27:2427-2437. [DOI: 10.1016/j.bmc.2019.02.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/28/2019] [Accepted: 02/02/2019] [Indexed: 10/27/2022]
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Suemoto H, Matsuzaki Y, Iwahashi F. Metyltetraprole, a novel putative complex III inhibitor, targets known QoI-resistant strains of Zymoseptoria tritici and Pyrenophora teres. PEST MANAGEMENT SCIENCE 2019; 75:1181-1189. [PMID: 30520257 PMCID: PMC6590148 DOI: 10.1002/ps.5288] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 05/04/2023]
Abstract
BACKGROUND Metyltetraprole is a new fungicide with a unique tetrazolinone-moiety and a similar side chain to a known quinone outside inhibitor (QoI), pyraclostrobin. In this study we describe a unique bioactivity of metyltetraprole on QoI-resistant strains of Zymoseptoria tritici and Pyrenophora teres. RESULTS Metyltetraprole exhibited potent antifungal activity against Ascomycetes; it was especially effective against Z. tritici and P. teres in seedling pot tests. Metyltetraprole was also effective in field tests with QoI-resistant mutants. Antifungal activity tests using field strains of Z. tritici and P. teres showed that the performance of metyltetraprole was unaltered by QoI, succinate dehydrogenase inhibitor (SDHI), and sterol 14α-demethylation inhibitor (DMI) resistance. However, the mitochondrial activity test indicated that the compound inhibits the respiratory chain via complex III. CONCLUSION Metyltetraprole is a novel fungicide that is highly effective against a wide range of fungal diseases, including important cereal diseases. Although metyltetraprole most likely inhibits the respiratory chain via complex III, it remains effective against QoI resistant strains. Therefore, metyltetraprole is considered as a novel fungicidal agent for controlling diseases affecting cereal crops and overcoming pathogen resistance to existing fungicides. © 2018 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Haruka Suemoto
- Health & Crop Sciences Research LaboratorySumitomo Chemical Co., LtdTakarazukaJapan
| | - Yuichi Matsuzaki
- Health & Crop Sciences Research LaboratorySumitomo Chemical Co., LtdTakarazukaJapan
| | - Fukumatsu Iwahashi
- Health & Crop Sciences Research LaboratorySumitomo Chemical Co., LtdTakarazukaJapan
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Zhang R, Xu Q, Zhang Y, Zhu F. Baseline Sensitivity and Toxic Actions of Prochloraz to Sclerotinia sclerotiorum. PLANT DISEASE 2018; 102:2149-2157. [PMID: 30145954 DOI: 10.1094/pdis-01-18-0148-re] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The ergosterol biosynthesis inhibitor prochloraz is a broad-spectrum fungicide and has been registered in China since 2007 for control of the economically important necrotrophic pathogen Sclerotinia sclerotiorum. In this study, relative baseline sensitivity and toxic actions of prochloraz on S. sclerotiorum were investigated. The mean EC50 values (effective concentrations causing 50% mycelial growth inhibition) for isolates collected in 2008 (n = 73) and 2014 (n = 76) were 0.0463 and 0.0434 µg/ml, respectively. There was no significant difference (P = 0.348) in EC50 values between the two years. Both frequency distributions of EC50 values for 2008 and 2014 were unimodal. The curative efficacy of prochloraz was significantly higher (P < 0.05) than that of the reference fungicide carbendazim. Prochloraz in potato dextrose agar (PDA) at concentrations from 0.01 to 0.36 µg/ml had no significant (P = 0.574) effects on the weight of sclerotia, but the number of sclerotia per plate increased for treatments with prochloraz at 0.15 and 0.36 µg/ml. Light microscopic observations showed that prochloraz in PDA at 0.03 µg/ml increased the number of hyphal offshoots. Observations with a transmission electron microscope showed that the cell wall of the prochloraz-treated hyphae became thicker and darker than the nontreated control. Prochloraz at 0.01 and 0.04 µg/ml significantly (P < 0.001) reduced rather than increased cell membrane permeability. Prochloraz significantly (P = 0.041) increased the mannan content in the cell wall of S. sclerotiorum. The observed mycelial growth inhibitions for the mixtures of prochloraz at 0.03 µg/ml and Congo red at a dose range from 0.05 to 0.4% (w/v) were lower than the expected inhibitions, indicating prochloraz might reduce the content of chitin in S. sclerotiorum. These results demonstrate that prochloraz has significant effects on the morphology and components of the cell wall of S. sclerotiorum and thus will advance our understanding of the toxic actions of prochloraz on phytopathogenic fungi.
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Affiliation(s)
- Ran Zhang
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qianru Xu
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yuchao Zhang
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Fuxing Zhu
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
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Ali EM, Amiri A. Selection Pressure Pathways and Mechanisms of Resistance to the Demethylation Inhibitor-Difenoconazole in Penicillium expansum. Front Microbiol 2018; 9:2472. [PMID: 30429831 PMCID: PMC6220093 DOI: 10.3389/fmicb.2018.02472] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 09/27/2018] [Indexed: 11/13/2022] Open
Abstract
Penicillium expansum causes blue mold, the most economically important postharvest disease of pome fruit worldwide. Beside sanitation practices, the disease is managed through fungicide applications at harvest. Difenoconazole (DIF) is a new demethylation inhibitor (DMI) fungicide registered recently to manage postharvest diseases of pome fruit. Herein, we evaluated the sensitivity of 130 P. expansum baseline isolates never exposed to DIF and determined the effective concentration (EC50) necessary to inhibit 50% germination, germ tube length, and mycelial growth. The respective mean EC50 values of 0.32, 0.26, and 0.18 μg/ml indicate a high sensitivity of P. expansum baseline isolates to DIF. We also found full and extended control efficacy in vivo after 6 months of storage at 1°C. We conducted a risk assessment for DIF-resistance development using ultraviolet excitation combined with or without DIF-selection pressure to generate and characterize lab mutants. Fifteen DIF-resistant mutants were selected and showed EC50 values of 0.92 to 1.4 μg/ml and 1.7 to 3.8 μg/ml without and with a DIF selection pressure, respectively. Resistance to DIF was stable in vitro over a 10-week period without selection pressure. Alignment of the full CYP51 gene sequences from the three wild-type and 15 mutant isolates revealed a tyrosine to phenylalanine mutation at codon 126 (Y126F) in all of the 15 mutants but not in the wild-type parental isolates. Resistance factors increased 5 to 15-fold in the mutants compared to the wild-type-isolates. DIF-resistant mutants also displayed enhanced CYP51 expression by 2 to 14-fold and was positively correlated with the EC50 values (R 2 = 0.8264). Cross resistance between DIF and fludioxonil, the mixing-partner in the commercial product, was not observed. Our findings suggest P. expansum resistance to DIF is likely to emerge in commercial packinghouse when used frequently. Future studies will determine whether resistance to DIF is qualitative or quantitative which will be determinant in the speed at which resistance will develop and spread in commercial packinghouses and to develop appropriate strategies to extend the lifespan of this new fungicide.
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Affiliation(s)
| | - Achour Amiri
- Department of Plant Pathology, Tree Fruit Research and Extension Center, Washington State University, Wenatchee, WA, United States
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Hawkins NJ, Fraaije BA. Fitness Penalties in the Evolution of Fungicide Resistance. ANNUAL REVIEW OF PHYTOPATHOLOGY 2018; 56:339-360. [PMID: 29958074 DOI: 10.1146/annurev-phyto-080417-050012] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The evolution of resistance poses an ongoing threat to crop protection. Fungicide resistance provides a selective advantage under fungicide selection, but resistance-conferring mutations may also result in fitness penalties, resulting in an evolutionary trade-off. These penalties may result from the functional constraints of an evolving target site or from the resource allocation costs of overexpression or active transport. The extent to which such fitness penalties are present has important implications for resistance management strategies, determining whether resistance persists or declines between treatments, and for resistance risk assessments for new modes of action. Experimental results have proven variable, depending on factors such as temperature, nutrient status, osmotic or oxidative stress, and pathogen life-cycle stage. Functional genetics tools allow pathogen genetic background to be controlled, but this in turn raises the question of epistatic interactions. Combining fitness penalties under various conditions into a field-realistic scenario poses an important future challenge.
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Affiliation(s)
- N J Hawkins
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom;
| | - B A Fraaije
- Biointeractions and Crop Protection Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, United Kingdom;
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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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Elevated MIC Values of Imidazole Drugs against Aspergillus fumigatus Isolates with TR 34/L98H/S297T/F495I Mutation. Antimicrob Agents Chemother 2018; 62:AAC.01549-17. [PMID: 29507067 DOI: 10.1128/aac.01549-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Accepted: 02/25/2018] [Indexed: 11/20/2022] Open
Abstract
The use of azole fungicides in agriculture is believed to be one of the main reasons for the emergence of azole resistance in Aspergillus fumigatus Though widely used in agriculture, imidazole fungicides have not been linked to resistance in A. fumigatus This study showed that elevated MIC values of imidazole drugs were observed against A. fumigatus isolates with TR34/L98H/S297T/F495I mutation, but not among isolates with TR34/L98H mutation. Short-tandem-repeat (STR) typing analysis of 580 A. fumigatus isolates from 20 countries suggested that the majority of TR34/L98H/S297T/F495I strains from China were genetically different from the predominant major clade comprising most of the azole-resistant strains and the strains with the same mutation from the Netherlands and Denmark. Alignments of sterol 14α-demethylase sequences suggested that F495I in A. fumigatus was orthologous to F506I in Penicillium digitatum and F489L in Pyrenophora teres, which have been reported to be associated with imidazole resistance. In vitro antifungal susceptibility testing of different recombinants with cyp51A mutations further confirmed the association of the F495I mutation with imidazole resistance. In conclusion, this study suggested that environmental use of imidazole fungicides might confer selection pressure for the emergence of azole resistance in A. fumigatus.
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3-pyridyl inhibitors with novel activity against Trypanosoma cruzi reveal in vitro profiles can aid prediction of putative cytochrome P450 inhibition. Sci Rep 2018; 8:4901. [PMID: 29559688 PMCID: PMC5861127 DOI: 10.1038/s41598-018-22043-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 02/09/2018] [Indexed: 01/04/2023] Open
Abstract
Using high throughput, high-content imaging, a proprietary library was screened against intracellular Trypanosoma cruzi amastigotes to identify compounds with novel activity against the parasite. Five inhibitors were discovered, which did not clear all of the parasites from 3T3 host cells following 48 hours exposure, and were identified as putative T. cruzi cytochrome P450 (TcCYP51) inhibitors. TcCYP51 inhibitors are not favourable for the drug discovery pipeline for treatment of Chagas Disease infection due to clinical and pre-clinical failures. To determine if there were in vitro inhibitory characteristics of these compounds that could aid the prediction of TcCYP51 inhibition further profiling using imaging and fluorescence based assays was undertaken. It was determined that in vitro profiles, coupled with analysis of chemical structure, could support the early prediction of putative TcCYP51 activity and thus enable early de-prioritisation of these compounds from progression through the drug discovery pipeline.
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Hollomon D. Does agricultural use of azole fungicides contribute to resistance in the human pathogen Aspergillus fumigatus? PEST MANAGEMENT SCIENCE 2017; 73:1987-1993. [PMID: 28485100 DOI: 10.1002/ps.4607] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 05/02/2017] [Accepted: 05/03/2017] [Indexed: 06/07/2023]
Abstract
Azole resistance in human fungal pathogens has increased over the past twenty years, especially in immunocompromised patients. Similarities between medical and agricultural azoles, and extensive azole (14α-demethylase inhibitor, DMI) use in crop protection, prompted speculation that resistance in patients with aspergillosis originated in the environment. Aspergillus species, and especially Aspergillus fumigatus, are the largest cause of patient deaths from fungi. Azole levels in soils following crop spraying, and differences in sensitivity between medical and agricultural azoles (DMIs), indicate weaker selection in cropping systems than in patients receiving azole therapy. Most fungi have just one CYP51 paralogue (isozyme CYP51B), but in Aspergillus sp. mutations conferring azole resistance are largely confined to a second paralogue, CYP51A. Binding within the active centre is similar for medical and agricultural azoles but differences elsewhere between the two paralogues may ensure selection depends on the DMI used on crops. Two imidazoles, imazalil and prochloraz, have been widely used since the early 1970s, yet unlike triazoles they have not been linked to resistance in patients. Evidence that DMIs are the origin, or increase the frequency, of azole resistance in human fungal pathogens is lacking. Limiting DMI use would have serious impacts on disease control in many crops, and remove key tools in anti-resistance strategies. © 2017 Society of Chemical Industry.
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Abstract
Aspergillus species are ubiquitous fungal saprophytes found in diverse ecological niches worldwide. Among them, Aspergillus fumigatus is the most prevalent and is largely responsible for the increased incidence of invasive aspergillosis with high mortality rates in some immunocompromised hosts. Azoles are the first-line drugs in treating diseases caused by Aspergillus spp. However, increasing reports in A. fumigatus azole resistance, both in the clinical setting and in the environment, are threatening the effectiveness of clinical and agricultural azole drugs. The azole target is the 14-α sterol demethylase encoded by cyp51A gene and the main mechanisms of resistance involve the integration of tandem repeats in its promoter and/or single point mutations in this gene. In A. fumigatus, azole resistance can emerge in two different scenarios: a medical route in which azole resistance is generated during long periods of azole treatment in the clinical setting and a route of resistance derived from environmental origin due to extended use of demethylation inhibitors in agriculture. The understanding of A. fumigatus azole resistance development and its evolution is needed in order to prevent or minimize its impact. In this article, we review the current situation of azole resistance epidemiology and the predominant molecular mechanisms described based on the resistance acquisition routes. In addition, the clinical implications of A. fumigatus azole resistance and future research are discussed.
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