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Hamilton R, Jacobs JL, McCoy AG, Kelly HM, Bradley CA, Malvick DK, Rojas JA, Chilvers MI. Multistate Sensitivity Monitoring of Fusarium virguliforme to the SDHI Fungicides Fluopyram and Pydiflumetofen in the United States. PLANT DISEASE 2024; 108:1602-1611. [PMID: 38127633 DOI: 10.1094/pdis-11-23-2465-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: 12/23/2023]
Abstract
Sudden death syndrome (SDS), caused by Fusarium virguliforme, is an important yield-limiting disease of soybean (Glycine max). From 1996 to 2022, cumulative yield losses attributed to SDS in North America totaled over 25 million metric tons, which was valued at over US $7.8 billion. Seed treatments are widely used to manage SDS by reducing early season soybean root infection by F. virguliforme. Fluopyram (succinate dehydrogenase inhibitor [SDHI] - FRAC 7), a fungicide seed treatment for SDS management, has been registered for use on soybean in the United States since 2014. A baseline sensitivity study conducted in 2014 evaluated 130 F. virguliforme isolates collected from five states to fluopyram in a mycelial growth inhibition assay and reported a mean EC50 of 3.35 mg/liter. This baseline study provided the foundation for the objectives of this research: to detect any statistically significant change in fluopyram sensitivity over time and geographical regions within the United States and to investigate sensitivity to the fungicide pydiflumetofen. We repeated fluopyram sensitivity testing on a panel of 80 historical F. virguliforme isolates collected from 2006 to 2013 (76 of which were used in the baseline study) and conducted testing on 123 contemporary isolates collected from 2016 to 2022 from 11 states. This study estimated a mean absolute EC50 of 3.95 mg/liter in isolates collected from 2006 to 2013 and a mean absolute EC50 of 4.19 mg/liter in those collected in 2016 to 2022. There was no significant change in fluopyram sensitivity (P = 0.1) identified between the historical and contemporary isolates. A subset of 23 isolates, tested against pydiflumetofen under the same conditions, estimated an absolute mean EC50 of 0.11 mg/liter. Moderate correlation was detected between fluopyram and pydiflumetofen sensitivity estimates (R = 0.53; P < 0.001). These findings enable future fluopyram and pydiflumetofen resistance monitoring and inform current soybean SDS management strategies in a regional and national context.
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Affiliation(s)
- Ryan Hamilton
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Janette L Jacobs
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Austin G McCoy
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Heather M Kelly
- Department of Entomology and Plant Pathology, The University of Tennessee Institute of Agriculture, Jackson, TN 38301
| | - Carl A Bradley
- Department of Plant Pathology, University of Kentucky, Princeton, KY 42445
| | - Dean K Malvick
- Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108
| | - J Alejandro Rojas
- Department of Entomology and Plant Pathology, University of Arkansas, Fayetteville, AR 72701
| | - Martin I Chilvers
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
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Liu J, Wu J, Jin P, Hu J, Lamour K, Yang Z. Activity of the Succinate Dehydrogenase Inhibitor Fungicide Benzovindiflupyr Against Clarireedia spp. PLANT DISEASE 2023; 107:3924-3932. [PMID: 37340553 DOI: 10.1094/pdis-02-23-0201-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: 06/22/2023]
Abstract
Dollar spot (DS), caused by Clarireedia spp. (formerly Sclerotinia homoeocarpa), is one of the most important diseases of turfgrasses worldwide. Benzovindiflupyr, a pyrazole carboxamide fungicide belonging to succinate dehydrogenase inhibitors, was recently registered for DS control. In this study, baseline sensitivity, toxicity, and control efficacy of benzovindiflupyr against Clarireedia spp. were evaluated. The frequency of sensitivities had a unimodal distribution (Kolmogorov-Smirnov, P > 0.10). The mean EC50 value was 1.109 ± 0.555 μg/ml, with individual values ranging from 0.160 to 2.548 μg/ml. Benzovindiflupyr increased the number of hyphal offshoots and cell membrane permeability and inhibited oxalic acid production. Positive cross-resistance was observed between benzovindiflupyr and boscalid, but not between benzovindiflupyr and thiophanate-methyl, propiconazole, or iprodione. Benzovindiflupyr showed high protective and curative control efficacies in vivo and in field applications. Both protective and curative control efficacies of benzovindiflupyr were significantly better than propiconazole, and equivalent to boscalid, over 2 years of field research. The results have important implications for managing DS and fungicide resistance problems in Clarireedia spp.
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Affiliation(s)
- Jun Liu
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing 210095, P.R. China
| | - Jiaxuan Wu
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing 210095, P.R. China
| | - Peiyuan Jin
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing 210095, P.R. China
| | - Jian Hu
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing 210095, P.R. China
| | - Kurt Lamour
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, U.S.A
| | - Zhimin Yang
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing 210095, P.R. China
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Neupane S, Avin FA, Liyanapathiranage P, Simmons T, Baysal-Gurel F. Identification and Chemical and Biological Management of Fusarium Root and Crown Rot Disease of Oakleaf Hydrangea. PLANT DISEASE 2023; 107:3188-3197. [PMID: 36890131 DOI: 10.1094/pdis-11-22-2609-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: 06/18/2023]
Abstract
Oakleaf hydrangea (Hydrangea quercifolia) is an important ornamental plant grown in Tennessee. In May 2018, after late spring frost, cultivars Pee Wee and Queen of Hearts showed root and crown rot symptoms and identification and management of the disease was a major concern. The objective of this research was to identify the causal organism of this disease and develop management recommendations for nursery growers. Isolates from the infected root and crown parts were subjected to microscopy, and the morphology of fungi resembled Fusarium. Molecular analysis was conducted by amplifying the internal transcribed spacer of ribosomal DNA, β-tubulin, and translation elongation factor 1-α regions. Fusarium oxysporum was identified as a causal organism based on molecular analysis. A pathogenicity test was done to complete the Koch's postulates by drenching containerized oakleaf hydrangea with a conidial suspension. Experiments were conducted to evaluate different chemical fungicides and biological products with different rates for Fusarium root and crown rot management in container-grown Queen of Hearts. Plants were inoculated by drenching containerized oakleaf hydrangea with 150-ml conidial suspensions of F. oxysporum, maintaining the concentration of 1 × 106 conidia/ml. Root and crown rot were assessed using a scale of 0 to 100%. Recovery of F. oxysporum was recorded by plating root and crown sections. Chemical fungicides such as mefentrifluconazole (BAS75002F), the low rate (1.09 ml/liter) of difenoconazole + pydiflumetofen (Postiva), and the high rate (1.32 ml/liter) of isofetamid (Astun) and biopesticide were applied; the high rate (1.64 g/liter) of ningnanmycin (SP2700 WP) effectively reduced Fusarium root rot severity and pyraclostrobin effectively reduced Fusarium crown rot severity in both trials.
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Affiliation(s)
- Sandhya Neupane
- Department of Agricultural and Environmental Sciences, Otis L. Floyd Nursery Research Center, Tennessee State University, McMinnville, TN 37110
| | - Farhat A Avin
- Department of Agricultural and Environmental Sciences, Otis L. Floyd Nursery Research Center, Tennessee State University, McMinnville, TN 37110
| | - Prabha Liyanapathiranage
- Department of Agricultural and Environmental Sciences, Otis L. Floyd Nursery Research Center, Tennessee State University, McMinnville, TN 37110
| | - Terri Simmons
- Department of Agricultural and Environmental Sciences, Otis L. Floyd Nursery Research Center, Tennessee State University, McMinnville, TN 37110
| | - Fulya Baysal-Gurel
- Department of Agricultural and Environmental Sciences, Otis L. Floyd Nursery Research Center, Tennessee State University, McMinnville, TN 37110
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Huangwei Z, Peiyuan J, Yixuan K, Zhimin Y, Yuxin Z, Geunhwa J, Jian H. Genome-wide transcriptional analyses of Clarireedia jacksonii isolates associated with multi-drug resistance. Front Microbiol 2023; 14:1266045. [PMID: 37840738 PMCID: PMC10570728 DOI: 10.3389/fmicb.2023.1266045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 08/30/2023] [Indexed: 10/17/2023] Open
Abstract
Emerging multidrug resistance (MDR) in Clarireedia spp. is a huge challenge to the management of dollar spot (DS) disease on turfgrass. Insight into the molecular basis of resistance mechanisms may help identify key molecular targets for developing novel effective chemicals. Previously, a MDR isolate (LT586) of C. jacksonii with significantly reduced sensitivities to propiconazole, boscalid, and iprodione, and a fungicide-sensitive isolate (LT15) of the same species were isolated from creeping bentgrass (Agrostis stolonifera L.). The present study aimed to further explore the molecular mechanisms of resistance by using genome-wide transcriptional analyses of the two isolates. A total of 619 and 475 differentially expressed genes (DEGs) were significantly down and upregulated in the MDR isolate LT586, compared with the sensitive isolate LT15 without fungicide treatment. Three hundreds and six and 153 DEGs showed significantly lower and higher expression in the MDR isolate LT586 than those in the sensitive isolate LT15, which were commonly induced by the three fungicides. Most of the 153 upregulated DEGs were xenobiotic detoxification-related genes and genes with transcriptional functions. Fifty and 17 upregulated DEGs were also commonly observed in HRI11 (a MDR isolate of the C. jacksonii) compared with the HRS10 (a fungicide-sensitive isolate of same species) from a previous study without and with the treatment of propiconazole, respectively. The reliability of RNA-seq data was further verified by qRT-PCR method using a few select potentially MDR-related genes. Results of this study indicated that there were multiple uncharacterized genes, possibly responsible for MDR phenotypes in Clarireedia spp., which may have important implications in understanding the molecular mechanisms underlying MDR resistance.
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Affiliation(s)
- Zhang Huangwei
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Jin Peiyuan
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Kong Yixuan
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Yang Zhimin
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Zhou Yuxin
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China
| | - Jung Geunhwa
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, United States
| | - Hu Jian
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
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Zhou F, Cui YX, Zhou YD, Duan ST, Wang ZY, Xia ZH, Hu HY, Liu RQ, Li CW. Baseline Pydiflumetofen Sensitivity of Fusarium pseudograminearum Isolates Collected from Henan, China, and Potential Resistance Mechanisms. PLANT DISEASE 2023; 107:2417-2423. [PMID: 36691280 DOI: 10.1094/pdis-08-22-1852-re] [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] [Indexed: 06/17/2023]
Abstract
Fusarium crown rot (FCR), caused by Fusarium pseudograminearum, is one of the most important diseases impacting wheat production in the Huanghuai region, the most important wheat-growing region of China. The current study found that the SDHI fungicide pydiflumetofen, which was recently developed by Syngenta Crop Protection, provided effective control of 67 wild-type F. pseudograminearum isolates in potato dextrose agar, with an average EC50 value of 0.060 ± 0.0098 μg/ml (SE). Further investigation revealed that the risk of fungicide resistance in pydiflumetofen was medium to high. Four F. pseudograminearum mutants generated by repeated exposure to pydiflumetofen under laboratory conditions indicated that pydiflumetofen resistance was associated with fitness penalties. Mutants exhibited significantly (P < 0.05) reduced sporulation in mung bean broth and significantly (P < 0.05) reduced pathogenicity in wheat seedlings. Sequence analysis indicated that the observed pydiflumetofen resistance of the mutants was likely associated with amino acid changes in the different subunits of the succinate dehydrogenase target protein, including R18L and V160M substitutions in the FpSdhA sequence; D69V, D147G, and C257R in FpSdhB; and W78R in FpSdhC. This study found no evidence of cross-resistance between pydiflumetofen and the alternative fungicides tebuconazole, fludioxonil, carbendazim, or fluazinam, which all have distinct modes of action and could therefore be used in combination or rotation with pydiflumetofen to reduce the risk of resistance emerging in the field. Taken together, these results indicate that pydiflumetofen has potential as a novel fungicide for the control of FCR caused by F. pseudograminearum and could therefore be of great significance in ensuring high and stable wheat yields in China.
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Affiliation(s)
- Feng Zhou
- School of Food Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
- Postdoctoral Research Base, Henan Institute of Science and Technology, Xinxiang 453003, China
- Henan Engineering Research Center of Crop Genome Editing/Henan International Joint Laboratory of Plant Genetic Improvement and Soil Remediation, Henan Institute of Science and Technology, Xinxiang 453003, China
- Henan Engineering Research Center of Green Pesticide Creation and Pesticide Residue Monitoring by Intelligent Sensor, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Ye-Xian Cui
- Henan Engineering Research Center of Crop Genome Editing/Henan International Joint Laboratory of Plant Genetic Improvement and Soil Remediation, Henan Institute of Science and Technology, Xinxiang 453003, China
- Henan Engineering Research Center of Green Pesticide Creation and Pesticide Residue Monitoring by Intelligent Sensor, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Yu-Dong Zhou
- Henan Engineering Research Center of Crop Genome Editing/Henan International Joint Laboratory of Plant Genetic Improvement and Soil Remediation, Henan Institute of Science and Technology, Xinxiang 453003, China
- Henan Engineering Research Center of Green Pesticide Creation and Pesticide Residue Monitoring by Intelligent Sensor, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Si-Tong Duan
- Henan Engineering Research Center of Crop Genome Editing/Henan International Joint Laboratory of Plant Genetic Improvement and Soil Remediation, Henan Institute of Science and Technology, Xinxiang 453003, China
- Henan Engineering Research Center of Green Pesticide Creation and Pesticide Residue Monitoring by Intelligent Sensor, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Zi-Yi Wang
- Henan Engineering Research Center of Crop Genome Editing/Henan International Joint Laboratory of Plant Genetic Improvement and Soil Remediation, Henan Institute of Science and Technology, Xinxiang 453003, China
- Henan Engineering Research Center of Green Pesticide Creation and Pesticide Residue Monitoring by Intelligent Sensor, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Zhi-Hao Xia
- Henan Engineering Research Center of Crop Genome Editing/Henan International Joint Laboratory of Plant Genetic Improvement and Soil Remediation, Henan Institute of Science and Technology, Xinxiang 453003, China
- Henan Engineering Research Center of Green Pesticide Creation and Pesticide Residue Monitoring by Intelligent Sensor, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Hai-Yan Hu
- Henan Engineering Research Center of Crop Genome Editing/Henan International Joint Laboratory of Plant Genetic Improvement and Soil Remediation, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Run-Qiang Liu
- Henan Engineering Research Center of Green Pesticide Creation and Pesticide Residue Monitoring by Intelligent Sensor, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Cheng-Wei Li
- School of Food Science and Engineering, Henan University of Technology, Zhengzhou 450001, China
- Henan Engineering Research Center of Crop Genome Editing/Henan International Joint Laboratory of Plant Genetic Improvement and Soil Remediation, Henan Institute of Science and Technology, Xinxiang 453003, China
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Ghimire B, Aktaruzzaman M, Chowdhury SR, Spratling WT, Vermeer CB, Buck JW, Martinez-Espinoza AD, Bahri BA. Sensitivity of Clarireedia spp. to benzimidazoles and dimethyl inhibitors fungicides and efficacy of biofungicides on dollar spot of warm season turfgrass. FRONTIERS IN PLANT SCIENCE 2023; 14:1155670. [PMID: 37360709 PMCID: PMC10288879 DOI: 10.3389/fpls.2023.1155670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 05/24/2023] [Indexed: 06/28/2023]
Abstract
Dollar spot caused by Clarireedia spp. (formerly Sclerotinia homoeocarpa) is an economically destructive fungal disease of turfgrass that can significantly compromise turf quality, playability, and aesthetic value. Fungicides are frequently used to manage the disease but are costly and potentially unfavorable to the environment. Repeated use of some active ingredients has resulted in reduced efficacy on C. jacksonii causing dollar spot in cool-season turfgrasses in the US. Experiments were conducted to study fungicide sensitivity of Clarireedia spp. as well as to develop alternatives to fungicides against dollar spot on warm-season turfgrass in Georgia. First, 79 isolates of Clarireedia spp. collected across the state were tested on fungicide-amended agar plates for their sensitivity to thiophanate-methyl (benzimidazole) and propiconazole (dimethyl inhibitor). Seventy-seven isolates (97.5%) were sensitive (0.001 to 0.654 μg/mL) and two isolates (2.5%) were found resistant (>1000 μg/mL) to thiophanate-methyl. However, in the case of propiconazole, 27 isolates (34.2%) were sensitive (0.005 to 0.098 μg/mL) while 52 isolates (65.8%) were resistant (0.101 to 3.820 μg/mL). Next, the efficacy of three bio- and six synthetic fungicides and ten different combinations were tested in vitro against C. monteithiana. Seven bio- and synthetic fungicide spray programs comprising Bacillus subtilis QST713 and propiconazole were further tested, either alone or in a tank mix in a reduced rate, on dollar spot infected bermudagrass 'TifTuf' in growth chamber and field environments. These fungicides were selected as they were found to significantly reduce pathogen growth up to 100% on in vitro assays. The most effective spray program in growth chamber assays was 100% B. subtilis QST713 in rotation with 75% B. subtilis QST713 + 25% propiconazole tank mix applied every 14 days. However, the stand-alone application of the biofungicide B. subtilis QST713 every seven days was an effective alternative and equally efficacious as propiconazole, suppressing dollar spot severity and AUDPC up to 75%, while resulting in acceptable turf quality (>7.0) in field experiments. Our study suggests that increased resistance of Clarireedia spp. to benzimidazoles and dimethyl inhibitors warrants continuous surveillance and that biofungicides hold promise to complement synthetic fungicides in an efficacious and environmentally friendly disease management program.
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Affiliation(s)
- Bikash Ghimire
- Department of Plant Pathology, University of Georgia, Griffin, GA, United States
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Griffin, GA, United States
| | - Md. Aktaruzzaman
- Department of Plant Pathology, University of Georgia, Tifton, GA, United States
| | - Shukti R. Chowdhury
- Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh
| | - Willis T. Spratling
- Department of Plant Pathology, University of Georgia, Griffin, GA, United States
| | - C. Brian Vermeer
- Department of Plant Pathology, University of Georgia, Griffin, GA, United States
| | - James W. Buck
- Department of Plant Pathology, University of Georgia, Griffin, GA, United States
| | | | - Bochra A. Bahri
- Department of Plant Pathology, University of Georgia, Griffin, GA, United States
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Griffin, GA, United States
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Alzohairy SA, Heger L, Nikzainalalam N, Miles TD. Cross-Resistance of Succinate Dehydrogenase Inhibitors (SDHI) in Botrytis cinerea and Development of Molecular Diagnostic Tools for SDHI Resistance Detection. PHYTOPATHOLOGY 2023; 113:998-1009. [PMID: 36596212 DOI: 10.1094/phyto-09-22-0346-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: 06/17/2023]
Abstract
Succinate dehydrogenase inhibitors (SDHIs) are keystone synthetic fungicides used to manage Botrytis cinerea in several hosts. In this study, we investigated the cross-resistance between five new SDHIs (pyraziflumid, isofetamid, benzovindiflupyr, fluxapyroxad, and pydiflumetofen) with commonly used SDHIs boscalid and fluopyram. Different mutations were detected in the sdhB gene in B. cinerea collected from Michigan grapes, and their frequency and EC50 value were determined. Among 216 B. cinerea boscalid-resistant isolates, five different mutations were detected, including H272R/Y, P225F/H, and N230I, at frequencies of 82.6, 4.3, 11.5, 0.4, and 5.3%, respectively. Five isolates of each genotype were used to screen the cross-resistance of the SDHIs. We classified the resistance profile of our mutants into five patterns. We report that all tested mutants were sensitive to benzovindiflupyr, indicating that it can be used as an effective fungicide against all B. cinerea mutants identified in this study. In addition, fluopyram, pydiflumetofen, and isofetamid can provide effective control according to which type of mutation is present in the field. We also developed and compared two molecular diagnostic tools, rhAMP and TaqMan assays, for rapid detection of SDHI resistance-associated mutants in B. cinerea. We report that the TaqMan assay was more successful than the rhAMP assay in detecting the B. cinerea mutant DNA at ≤10 pg and in a single assay was capable of monitoring two amino acid positions. Our results provide essential information about new SDHIs and provide molecular tools for monitoring SDHI resistance mutations, which will assist in gray mold disease control.
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Affiliation(s)
- S A Alzohairy
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
- Agricultural Genetic Engineering Research Institute, Agricultural Research Center, Giza 12619, Egypt
| | - L Heger
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - N Nikzainalalam
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - T D Miles
- Department of Plant Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
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Wang Y, Lu N, Wang K, Li Y, Zhang M, Liu S, Li Y, Zhou F. Fluxapyroxad Resistance Mechanisms in Sclerotinia sclerotiorum. PLANT DISEASE 2023; 107:1035-1043. [PMID: 36058635 DOI: 10.1094/pdis-07-22-1615-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: 06/15/2023]
Abstract
The necrotrophic pathogen Sclerotinia sclerotiorum has a global distribution and a wide host range, making it one of the most damaging and economically important of all plant pathogens. The current study found that fluxapyroxad, a typical succinate dehydrogenase inhibitor fungicide, had a strong inhibitory effect against S. sclerotiorum, with mean effective concentration for 50% inhibition (EC50) values ranging from 0.021 to 0.095 µg/ml. Further investigation of five highly resistant S. sclerotiorum mutants, with EC50 values of 12.37 to 31.36 µg/ml, found that fluxapyroxad resistance was accompanied by a certain cost to fitness. All of the mutants were found to have significantly (P < 0.05) reduced mycelial growth and altered sclerotia production in artificial culture, as well as reduced pathogenicity, compared with wild-type isolates, with one mutant completely losing the capacity to infect detached soybean leaves. Sequence analysis demonstrated that four of the mutants had point mutations leading to amino acid changes in the SsSdhB subunit of the fungicide target protein succinate dehydrogenase. In addition, two of the mutants were also found to have amino acid changes in the predicted sequence of their SsSdhD subunit, while the fifth mutant had no changes in any of its SsSdh sequences, indicating that an alternative mechanism might be responsible for the observed resistance in this mutant. No cross-resistance was found between fluxapyroxad and any of the other fungicides tested, including tebuconazole, prochloraz, dimethachlone, carbendazim, procymidone, pyraclostrobin, boscalid, fluazinam, fludioxonil, and cyprodinil, which indicates that fluxapyroxad has great potential as an alternative method of control for the Sclerotinia stem rot caused by S. sclerotiorum, and which could provide ongoing protection to the soybean fields of China.
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Affiliation(s)
- Yanfen Wang
- School of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003, China
- College of Plant Protection, Henan Agricultural University, Zhengzhou 450002, China
| | - Ninghai Lu
- School of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Kuaikuai Wang
- School of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Yinna Li
- School of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Mengli Zhang
- School of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Shuang Liu
- School of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Yanling Li
- School of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003, China
| | - Feng Zhou
- School of Resources and Environment, Henan Institute of Science and Technology, Xinxiang 453003, China
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Stergiopoulos I, Aoun N, van Huynh Q, Neill T, Lowder SR, Newbold C, Cooper ML, Ding S, Moyer MM, Miles TD, Oliver CL, Úrbez-Torres JR, Mahaffee WF. Identification of Putative SDHI Target Site Mutations in the SDHB, SDHC, and SDHD Subunits of the Grape Powdery Mildew Pathogen Erysiphe necator. PLANT DISEASE 2022; 106:2310-2320. [PMID: 35100029 DOI: 10.1094/pdis-09-21-1993-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Succinate dehydrogenase inhibitors (SDHIs) are fungicides used in control of numerous fungal plant pathogens, including Erysiphe necator, the causal agent of grapevine powdery mildew (GPM). Here, the sdhb, sdhc, and sdhd genes of E. necator were screened for mutations that may be associated with SDHI resistance. GPM samples were collected from 2017 to 2020 from the U.S. states of California, Oregon, Washington, and Michigan, and the Canadian province of British Columbia. Forty-five polymorphisms were identified in the three sdh genes, 17 of which caused missense mutations. Of these, the SDHC-p.I244V substitution was shown in this study to reduce sensitivity of E. necator to boscalid and fluopyram, whereas the SDHC-p.G25R substitution did not affect SDHI sensitivity. Of the other 15 missense mutations, the SDHC-p.H242R substitution was shown in previous studies to reduce sensitivity of E. necator toward boscalid, whereas the equivalents of the SDHB-p.H242L, SDHC-p.A83V, and SDHD-p.I71F substitutions were shown to reduce sensitivity to SDHIs in other fungi. Generally, only a single amino acid substitution was present in the SDHB, SDHC, or SDHD subunit of E. necator isolates, but missense mutations putatively associated with SDHI resistance were widely distributed in the sampled areas and increased in frequency over time. Finally, isolates that had decreased sensitivity to boscalid or fluopyram were identified but with no or only the SDHC-p.G25R amino acid substitution present in SDHB, SDHC, and SDHD subunits. This suggests that target site mutations probably are not the only mechanism conferring resistance to SDHIs in E. necator.
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Affiliation(s)
- Ioannis Stergiopoulos
- Department of Plant Pathology, University of California Davis, Davis, CA 95616-851, U.S.A
| | - Nathalie Aoun
- Department of Plant Pathology, University of California Davis, Davis, CA 95616-851, U.S.A
| | - Que van Huynh
- Department of Plant Pathology, University of California Davis, Davis, CA 95616-851, U.S.A
| | - Tara Neill
- USDA-ARS Horticulture Crops Disease and Pest Management Research Unit (HCDPMRU), Corvallis, OR 97330, U.S.A
| | - Sarah R Lowder
- Department of Botany and Plant Pathology, Oregon State University, Cordley Hall, OR 97331, U.S.A
| | - Chelsea Newbold
- Department of Botany and Plant Pathology, Oregon State University, Cordley Hall, OR 97331, U.S.A
| | - Monica L Cooper
- University of California Cooperative Extension, Napa, CA 94559, U.S.A
| | - Shunping Ding
- Wine and Viticulture Department, California Polytechnical State University, San Luis Obispo, CA 93407, U.S.A
| | - Michelle M Moyer
- Department of Horticulture, Washington State University Irrigated Agriculture Research and Extension Center, Prosser, WA 99350, U.S.A
| | - Timothy D Miles
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Charlotte L Oliver
- Department of Horticulture, Washington State University Irrigated Agriculture Research and Extension Center, Prosser, WA 99350, U.S.A
| | - José Ramón Úrbez-Torres
- Agriculture and Agri-Food Canada, Summerland Research and Development Centre, Summerland, British Columbia V0H 1Z0, Canada
| | - Walter F Mahaffee
- USDA-ARS Horticulture Crops Disease and Pest Management Research Unit (HCDPMRU), Corvallis, OR 97330, U.S.A
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Zhu J, Li J, Ma D, Gao Y, Cheng J, Mu W, Li B, Liu F. SDH mutations confer complex cross-resistance patterns to SDHIs in Corynespora cassiicola. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2022; 186:105157. [PMID: 35973770 DOI: 10.1016/j.pestbp.2022.105157] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/20/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
Succinate dehydrogenase inhibitors (SDHIs) are one of the most frequently used fungicides in cucumber fields in China. Our previous studies indicated that the sensitivity profile of Corynespora cassiicola, the causal agent of Corynespora leaf spot, to different SDHIs varied greatly; however, the underlying mechanism remains unclear. The 50% effective concentration (EC50) values of boscalid, fluopyram, fluxapyroxad and isopyrazam in C. cassiicola collected from 2017 to 2020 shifted, with resistance frequencies of 79.83%, 78.43%, 83.19% and 49.86%, respectively. The sequence alignment of sdhB/C/D of resistant strains revealed that eight single amino acid mutations (B-H278Y/L, B-I280V, C-S73P, C-N75S, C-H134R, D-D95E and D-G109V), and three dual-mutations (B-I280V&C-S73P, B-I280V&C-N75S and C-S73P&C-N75S) conferred various SDHI resistance levels and cross-resistance profiles. The expression level of the sdhB/C/D gene and succinate dehydrogenase (SDH) activity in the mutants were significantly altered by the presence of SDHIs, compared with the wild type strain. Additionally, molecular docking results suggested that the missense mutation influenced the crystal structure of SDH and subsequently interfered with the interaction bonds and bond distances among the target protein and chemicals. In brief, amino acid mutations altered the fungicide response of target gene expression, SDH activity and the binding features of SDH-ligand complexes and subsequently conferred multiple resistance levels and complex cross-resistance patterns to SDHIs in C. cassiicola. The evaluation of C. cassiicola resistance to SDHIs provided a significant foundation for efficient chemical development and integrated CLS management strategies.
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Affiliation(s)
- Jiamei Zhu
- Shandong Provincial Key Laboratory for the Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, China
| | - Jin Li
- Shandong Provincial Key Laboratory for the Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, China
| | - Dicheng Ma
- College of Plant Protection, China Agricultural University, No. 2, Yuanmingyuan West Road, Haidian District, Beijing 100193, PR China
| | - Yangyang Gao
- Shandong Provincial Key Laboratory for the Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, China
| | - Jiagao Cheng
- Shanghai Key Laboratory of Chemical Biology, Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Wei Mu
- Shandong Provincial Key Laboratory for the Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, China; Key Laboratory of Pesticide Toxicology and Application Technique, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, China
| | - Beixing Li
- Shandong Provincial Key Laboratory for the Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, China; Key Laboratory of Pesticide Toxicology and Application Technique, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, China
| | - Feng Liu
- Shandong Provincial Key Laboratory for the Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, China; Key Laboratory of Pesticide Toxicology and Application Technique, College of Plant Protection, Shandong Agricultural University, 61 Daizong Street, Tai'an, Shandong 271018, China.
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11
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Sapkota S, Catching KE, Raymer PL, Martinez-Espinoza AD, Bahri BA. New Approaches to an Old Problem: Dollar Spot of Turfgrass. PHYTOPATHOLOGY 2022; 112:469-480. [PMID: 34406790 DOI: 10.1094/phyto-11-20-0505-rvw] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Dollar spot, caused by fungal pathogens Clarireedia spp. (formerly Sclerotinia homoeocarpa), is the most common and widely distributed disease of turfgrass worldwide. It can drastically reduce the quality of turfgrass species and affect their aesthetic value and playability. Management of dollar spot typically includes a costly program of multiple application of fungicides within a growing season. Consequently, there have been reported cases of fungicide resistance in populations of Clarireedia spp. Host resistance could be an important component of dollar spot management; however, this approach has been hampered by the lack of sources of resistance because nearly all known warm- and cool-season turfgrass species are susceptible. With the recent advancement in genome sequencing technologies, studies on pathogen genomics and host-pathogen interactions are emerging with the hope of revealing candidate resistance genes in turfgrass and genes for virulence and pathogenicity in Clarireedia spp. Large-scale screening of turfgrass germplasm and quantitative trait locus (QTL) analysis for dollar spot resistance are important for resistance breeding, but only a handful of such studies have been conducted to date. This review summarizes currently available information on the dollar spot pathosystem, taxonomy, pathogen genomics, host-pathogen interaction, genetics of resistance, and QTL mapping and also provides some thoughts for future research prospects to better manage this disease.
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Affiliation(s)
- Suraj Sapkota
- Department of Plant Pathology, University of Georgia, Griffin, GA 30223
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Griffin, GA 30223
| | - Katherine E Catching
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Griffin, GA 30223
| | - Paul L Raymer
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Griffin, GA 30223
- Department of Crop and Soil Science, University of Georgia, Griffin, GA 30223
| | | | - Bochra A Bahri
- Department of Plant Pathology, University of Georgia, Griffin, GA 30223
- Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Griffin, GA 30223
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12
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Sang H, Chang HX, Choi S, Son D, Lee G, Chilvers MI. Genome-wide transcriptional response of the causal soybean sudden death syndrome pathogen Fusarium virguliforme to a succinate dehydrogenase inhibitor fluopyram. PEST MANAGEMENT SCIENCE 2022; 78:530-540. [PMID: 34561937 DOI: 10.1002/ps.6657] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Succinate dehydrogenase inhibitors (SDHIs) have been widely used to manage plant diseases caused by phytopathogenic fungi. Although attention to and use of SDHI fungicides has recently increased, molecular responses of fungal pathogens to SDHIs have often not been investigated. A SDHI fungicide, fluopyram, has been used as a soybean seed treatment and has displayed effective control of Fusarium virguliforme, one of the causal agents of soybean sudden death syndrome. To examine genome-wide gene expression of F. virguliforme to fluopyram, RNA-seq analysis was conducted on two field strains of F. virguliforme with differing SDHI fungicide sensitivity in the absence and presence of fluopyram. RESULTS The analysis indicated that several xenobiotic detoxification-related genes, such as those of deoxygenase, transferases and transporters, were highly induced by fluopyram. Among the genes, four ATP-binding cassette (ABC) transporters were characterized by the yeast expression system. The results revealed that expression of three ABCG transporters was associated with reduced sensitivity to multiple fungicides including fluopyram. In addition, heterologous expression of a major facilitator superfamily (MFS) transporter that was highly expressed in the fluopyram-insensitive F. virguliforme strain in the yeast system conferred decreased sensitivity to fluopyram. CONCLUSION This study demonstrated that xenobiotic detoxification-related genes were highly upregulated in response to fluopyram, and expression of ABC or MFS transporter genes was associated with reduced sensitivity to the SDHI fungicide. This is the first transcriptomic analysis of the fungal species response to fluopyram and the finding will help elucidate the molecular mechanisms of SDHI resistance. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Hyunkyu Sang
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan, USA
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, South Korea
- Kumho Life Science Laboratory, Chonnam National University, Gwangju, South Korea
| | - Hao-Xun Chang
- Department of Plant Pathology and Microbiology, National Taiwan University, Taipei, Taiwan
| | - Sungyu Choi
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Doeun Son
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Gahee Lee
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju, South Korea
| | - Martin I Chilvers
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan, USA
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13
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Li S, Li X, Zhang H, Wang Z, Xu H. The research progress in and perspective of potential fungicides: Succinate dehydrogenase inhibitors. Bioorg Med Chem 2021; 50:116476. [PMID: 34757244 DOI: 10.1016/j.bmc.2021.116476] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/24/2021] [Accepted: 10/11/2021] [Indexed: 12/21/2022]
Abstract
Succinate dehydrogenase inhibitors (SDHIs) have become one of the fastest growing classes of new fungicides since entering the market, and have attracted increasing attention as a result of their unique structure, high activity and broad fungicidal spectrum. The mechanism of SDHIs is to inhibit the activity of succinate dehydrogenase, thereby affecting mitochondrial respiration and ultimately killing pathogenic fungi. At present, they have become popular varieties researched and developed by major pesticide companies in the world. In the review, we focused on the mechanism, the history, the representative varieties, structure-activity relationship and resistance of SDHIs. Finally, the potential directions for the development of SDHIs were discussed. It is hoped that this review can strengthen the individuals' understanding of SDHIs and provide some inspiration for the development of new fungicides.
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Affiliation(s)
- Shuqi Li
- Engineering Research Center of Pesticide of Heilongjiang Province, College of Advanced Agriculture and Ecological Environment, Heilongjiang University, 150080 Harbin, China
| | - Xiangshuai Li
- Engineering Research Center of Pesticide of Heilongjiang Province, College of Advanced Agriculture and Ecological Environment, Heilongjiang University, 150080 Harbin, China
| | - Hongmei Zhang
- Engineering Research Center of Pesticide of Heilongjiang Province, College of Advanced Agriculture and Ecological Environment, Heilongjiang University, 150080 Harbin, China
| | - Zishi Wang
- Engineering Research Center of Pesticide of Heilongjiang Province, College of Advanced Agriculture and Ecological Environment, Heilongjiang University, 150080 Harbin, China.
| | - Hongliang Xu
- Engineering Research Center of Pesticide of Heilongjiang Province, College of Advanced Agriculture and Ecological Environment, Heilongjiang University, 150080 Harbin, China.
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14
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Gleason J, Peng J, Proffer TJ, Slack SM, Outwater CA, Rothwell NL, Sundin GW. Resistance to Boscalid, Fluopyram and Fluxapyroxad in Blumeriella jaapii from Michigan (U.S.A.): Molecular Characterization and Assessment of Practical Resistance in Commercial Cherry Orchards. Microorganisms 2021; 9:microorganisms9112198. [PMID: 34835322 PMCID: PMC8621041 DOI: 10.3390/microorganisms9112198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/15/2021] [Accepted: 10/17/2021] [Indexed: 11/16/2022] Open
Abstract
Management of cherry leaf spot disease, caused by the fungus Blumeriella jaapii, with succinate dehydrogenase inhibitor (SDHI) fungicides has been ongoing in Michigan tart cherry orchards for the past 17 years. After boscalid-resistant B. jaapii were first isolated from commercial orchards in 2010, premixes of SDHI fungicides fluopyram or fluxapyroxad with a quinone outside inhibitor were registered in 2012. Here, we report widespread resistance to fluopyram (FluoR), fluxapyroxad (FluxR), and boscalid (BoscR) in commercial orchard populations of B. jaapii in Michigan from surveys conducted between 2016 and 2019. A total of 26% of 1610 isolates from the 2016-2017 surveys exhibited the fully-resistant BoscR FluoR FluxR phenotype and only 7% were sensitive to all three SDHIs. Practical resistance to fluopyram and fluxapyroxad was detected in 29 of 35 and 14 of 35 commercial tart cherry orchards, respectively, in surveys conducted in 2018 and 2019. Sequencing of the SdhB, SdhC, and SdhD target genes from 22 isolates with varying resistance phenotypes showed that BoscS FluoR FluxS isolates harbored either an I262V substitution in SdhB or an S84L substitution in SdhC. BoscR FluoR FluxR isolates harbored an N86S substitution in SdhC, or contained the N86S substitution with the additional I262V substitution in SdhB. One BoscR FluoR FluxR isolate contained both the I262V substitution in SdhB and the S84L substitution in SdhC. These mutational analyses suggest that BoscR FluoR FluxR isolates evolved from fully sensitive BoscS, FluoS, FluxS isolates in the population and not from boscalid-resistant isolates that were prevalent in the 2010-2012 time period.
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Affiliation(s)
- Jacqueline Gleason
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, E. Lansing, MI 48824, USA; (J.G.); (J.P.); (T.J.P.); (S.M.S.); (C.A.O.)
| | - Jingyu Peng
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, E. Lansing, MI 48824, USA; (J.G.); (J.P.); (T.J.P.); (S.M.S.); (C.A.O.)
| | - Tyre J. Proffer
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, E. Lansing, MI 48824, USA; (J.G.); (J.P.); (T.J.P.); (S.M.S.); (C.A.O.)
| | - Suzanne M. Slack
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, E. Lansing, MI 48824, USA; (J.G.); (J.P.); (T.J.P.); (S.M.S.); (C.A.O.)
| | - Cory A. Outwater
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, E. Lansing, MI 48824, USA; (J.G.); (J.P.); (T.J.P.); (S.M.S.); (C.A.O.)
| | - Nikki L. Rothwell
- Northwest Michigan Horticultural Research Center, Traverse City, MI 49684, USA;
| | - George W. Sundin
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, E. Lansing, MI 48824, USA; (J.G.); (J.P.); (T.J.P.); (S.M.S.); (C.A.O.)
- Correspondence:
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15
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Resistance to the SDHI Fungicides Boscalid and Fluopyram in Podosphaera xanthii Populations from Commercial Cucurbit Fields in Spain. J Fungi (Basel) 2021; 7:jof7090733. [PMID: 34575771 PMCID: PMC8464660 DOI: 10.3390/jof7090733] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 08/27/2021] [Accepted: 09/06/2021] [Indexed: 01/23/2023] Open
Abstract
Powdery mildew is caused by Podosphaera xanthii, and is one of the most important diseases that attacks Spanish cucurbit crops. Fungicide application is the primary control tool; however, its effectiveness is hampered by the rapid development of resistance to these compounds. In this study, the EC50 values of 26 isolates were determined in response to the succinate dehydrogenase inhibitor (SDHI) fungicides boscalid and fluopyram. From these data, the discriminatory doses were deduced and used for SDHI resistance monitoring during the 2018 and 2019 growing seasons. Of the 298 isolates analysed, 37.9% showed resistance to boscalid and 44% to fluopyram. Although different phenotypes were observed in leaf disc assays, the resistant isolates showed the same phenotype in plant assays. Compared to sensitive isolates, two amino acid changes were found in the SdhC subunit, A86V and G151R, which are associated mostly with resistance patterns to fluopyram and boscalid, respectively. Furthermore, no significant differences were observed in terms of fitness cost between the selected sensitive and resistant isolates analysed here. Lastly, a loop-mediated isothermal amplification (LAMP) assay was developed to detect A86V and G151R mutations using conidia obtained directly from infected material. Our results show that growers could continue to use boscalid and fluopyram, but resistance management practices must be implemented.
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16
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Lee J, Elliott MR, Yamada T, Jung G. Field Assessment of Six Point-Mutations in SDH Subunit Genes Conferring Varying Resistance Levels to SDHIs in Clarireedia spp. PLANT DISEASE 2021; 105:1685-1691. [PMID: 33944573 DOI: 10.1094/pdis-06-20-1344-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Dollar spot, caused by Clarireedia spp. (formerly Sclerotinia homoeocarpa F.T. Bennett), is the most economically important turfgrass disease causing considerable damage on golf courses. While cultural practices are available for reducing dollar spot infection, chemical fungicide use is often necessary for maintaining optimal turf quality. Since the release of boscalid in 2003, the succinate dehydrogenase inhibitor (SDHI) class has become an invaluable tool for managing dollar spot. However, resistance to this class has recently been reported in Clarireedia spp. and many other plant pathogenic fungi. After SDHI field failure on four golf courses and one university research plot, a total of six unique SDH mutations conferring differential in vitro sensitivities to SDHIs have been identified in Clarireedia spp. In 2018 and 2019, turf research plots were inoculated with sensitive, non-mutated isolates of Clarireedia spp., as well as resistant isolates harboring each unique identified mutation. Fungicide efficacy trials were conducted on inoculated plots to assess differential sensitivity to five SDHI active ingredients (boscalid, fluxapyroxad, isofetamid, fluopyram, and pydiflumetofen) across mutations under field conditions. Results indicate unique mutations are associated with distinct SDHI field efficacy profiles as shown in in-vitro sensitivity assays. Isolate populations with B subunit mutations (H267Y/R) were more sensitive to fluopyram, whereas isolate populations with C subunit mutations (C-G91R, C-G150R) showed resistance to all SDHIs tested. Mutation-associated differential sensitivity observed under field conditions indicates a need for a nation-wide survey and frequent monitoring of SDHI sensitivity of dollar spot populations on golf courses in the USA. Further, the information gained from this study will be useful in providing sustainable management recommendations for controlling site-specific resistant populations of Clarireedia spp.
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Affiliation(s)
- Jaemin Lee
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, U.S.A
| | - Michaela R Elliott
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, U.S.A
| | - Toshihiko Yamada
- Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Hokkaido 0606-0808, Japan
| | - Geunhwa Jung
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, U.S.A
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17
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Peng J, Sang H, Proffer TJ, Gleason J, Outwater CA, Jung G, Sundin GW. A Method for the Examination of SDHI Fungicide Resistance Mechanisms in Phytopathogenic Fungi Using a Heterologous Expression System in Sclerotinia sclerotiorum. PHYTOPATHOLOGY 2021; 111:819-830. [PMID: 33141650 DOI: 10.1094/phyto-09-20-0421-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Succinate dehydrogenase inhibitors (SDHIs) are a class of broad-spectrum fungicides used for management of diseases caused by phytopathogenic fungi. In many cases, reduced sensitivity to SDHI fungicides has been correlated with point mutations in the SdhB and SdhC target genes that encode components of the succinate dehydrogenase complex. However, the genetic basis of SDHI fungicide resistance mechanisms has been functionally characterized in very few fungi. Sclerotinia sclerotiorum is a fast-growing and SDHI fungicide-sensitive phytopathogenic fungus that can be conveniently transformed. Given the high amino acid sequence similarity and putative structural similarity of SDHI protein target sites between S. sclerotiorum and other common phytopathogenic ascomycete fungi, we developed an in vitro heterologous expression system that used S. sclerotiorum as a reporter strain. With this system, we were able to demonstrate the function of mutant SdhB or SdhC alleles from several ascomycete fungi in conferring resistance to multiple SDHI fungicides. In total, we successfully validated the function of Sdh alleles that had been previously identified in field isolates of Botrytis cinerea, Blumeriella jaapii, and Clarireedia jacksonii (formerly S. homoeocarpa) in conferring resistance to boscalid, fluopyram, or fluxapyroxad and used site-directed mutagenesis to construct and phenotype a mutant allele that is not yet known to exist in Monilinia fructicola populations. We also examined the functions of these alleles in conferring cross-resistance to more recently introduced SDHIs including inpyrfluxam, pydiflumetofen, and pyraziflumid. The approach developed in this study can be widely applied to interrogate SDHI fungicide resistance mechanisms in other phytopathogenic ascomycetes.
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Affiliation(s)
- Jingyu Peng
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Hyunkyu Sang
- Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, Korea
| | - Tyre J Proffer
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Jacqueline Gleason
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Cory A Outwater
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Geunhwa Jung
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, U.S.A
| | - George W Sundin
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
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18
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Lee J, Elliott MR, Kim M, Yamada T, Jung G. A Rapid Molecular Detection System for SdhB and SdhC Point Mutations Conferring Differential Succinate Dehydrogenase Inhibitor Resistance in Clarireedia Populations. PLANT DISEASE 2021; 105:660-666. [PMID: 32757732 DOI: 10.1094/pdis-04-20-0724-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: 06/11/2023]
Abstract
Dollar spot, caused by the ascomycete fungus Clarireedia (formerly Sclerotinia), is one of the most resource-demanding diseases on amenity turfgrasses in North America. Differential resistance to the succinate dehydrogenase inhibitor (SDHI) fungicide class, conferred by singular point mutations on the SdhB, SdhC, and SdhD subunits of the succinate dehydrogenase enzyme (SDH), has been reported in dollar spot as well as many other plant-pathogenic fungal diseases. Four unique mutations were previously reported from Clarireedia field isolates collected from two different cool-season golf courses in Japan and Rhode Island: an amino acid substitution H267Y and a silent mutation (CTT to CTC) at codon 181 on the SdhB subunit gene, and amino acid substitutions G91R and G150R on the SdhC subunit gene. To properly diagnose and monitor SDHI resistance in the field, a rapid detection system for known mutations is crucial. As part of this study, additional SDHI-resistant Clarireedia isolates were collected from Rutgers University research plots and in vitro sensitivity to four SDHI active ingredients was assessed. SdhB, SdhC, and SdhD subunits of these isolates were sequenced to reveal an additional mutation on the SdhB subunit gene, H267R, not previously observed in Clarireedia. Cleaved amplified polymorphic sequence (CAPS) and derived CAPS molecular markers were developed to detect five mutations conferring SDHI resistance in Clarireedia isolates and validated using samples from two additional golf courses in Connecticut and Wisconsin experiencing SDHI field failure. This PCR-based molecular detection system will be useful for continued monitoring, assessment, and delay of SDHI resistance in the field.
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Affiliation(s)
- Jaemin Lee
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, U.S.A
| | - Michaela R Elliott
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, U.S.A
| | - Minsoo Kim
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, U.S.A
| | - Toshihiko Yamada
- Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Hokkaido 0606-0808, Japan
| | - Geunhwa Jung
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, U.S.A
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19
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Liu S, Fu L, Tan H, Jiang J, Che Z, Tian Y, Chen G. Resistance to Boscalid in Botrytis cinerea From Greenhouse-Grown Tomato. PLANT DISEASE 2021; 105:628-635. [PMID: 32820676 DOI: 10.1094/pdis-06-20-1191-re] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Gray mold, caused by the fungus Botrytis cinerea Pers ex Fr., is one of the most destructive spoilage diseases, severely affecting tomato production in Henan Province, China. Spraying fungicides from the flowering to the harvest stage is a necessary measure to reduce losses associated with B. cinerea infection. However, B. cinerea has developed resistance to fungicides in many countries. Boscalid is a succinate dehydrogenase inhibitor (SDHI) fungicide and was registered for the control of gray mold. In this study, a total of 269 B. cinerea isolates were collected from tomato in commercial greenhouses in different locations of Henan Province in 2014 and 2015. The sensitivity and resistance of B. cinerea field isolates were determined based on mycelial growth. The effective concentration 50 ranged from 0.11 to 15.92 µg/ml and 0.16 to 8.54 µg/ml, in 2014 and 2015, respectively. The frequency of low resistance to boscalid was 12.6 and 7.6%, and moderate resistance was 2.7 and 1.3% in 2014 and 2015, respectively. No highly resistant isolates were found in Henan Province, China. Mycelial growth, mycelial dry weight, spore production, and pathogenicity were not significantly different between resistant and sensitive phenotypes of the B. cinerea isolates. The results of cross-resistance testing showed no correlation between boscalid and carbendazim, procymidone, pyrimethanil, fluazinam, or fluopyram. In this study, the succinate dehydrogenase genes B (sdhB), C (sdhC), and D (sdhD) were analyzed and compared in sensitive and low-resistance and moderately resistant B. cinerea isolates to boscalid. Results showed that point mutations occurred simultaneously at sdhC amino acid positions 85 (G85A), 93 (I93V), 158 (M158V), and 168 (V168I) in 4 out of 10 sensitive isolates and 23 of 26 low-resistance and 5 of 5 moderately resistant B. cinerea isolates to boscalid. No point mutations were found in the sdhB and sdhD genes of all isolates. Furthermore, no point mutations were found in sdhB, sdhC, and sdhD genes in 3 of 26 low-resistance B. cinerea isolates to boscalid. Therefore, we speculate that the simultaneous point mutations in the sdhC gene may not be related to the resistance of B. cinerea to boscalid. These results suggested that there might be a substitution mechanism for the resistance of B. cinerea to the SDHI fungicide boscalid.
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Affiliation(s)
- Shengming Liu
- Department of Plant Protection, College of Forestry, Henan University of Science and Technology, Luoyang 471023, China
| | - Liuyuan Fu
- Department of Plant Protection, College of Forestry, Henan University of Science and Technology, Luoyang 471023, China
| | - Huanhuan Tan
- Department of Plant Protection, College of Forestry, Henan University of Science and Technology, Luoyang 471023, China
| | - Jia Jiang
- Department of Plant Protection, College of Forestry, Henan University of Science and Technology, Luoyang 471023, China
| | - Zhiping Che
- Department of Plant Protection, College of Forestry, Henan University of Science and Technology, Luoyang 471023, China
| | - Yuee Tian
- Department of Plant Protection, College of Forestry, Henan University of Science and Technology, Luoyang 471023, China
| | - Genqiang Chen
- Department of Plant Protection, College of Forestry, Henan University of Science and Technology, Luoyang 471023, China
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Groben G, Clarke BB, Murphy J, Koch P, Crouch JA, Lee S, Zhang N. Real-Time PCR Detection of Clarireedia spp., the Causal Agents of Dollar Spot in Turfgrasses. PLANT DISEASE 2020; 104:3118-3123. [PMID: 33058719 DOI: 10.1094/pdis-04-20-0726-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Dollar spot is one of the most economically important diseases of turfgrasses. Recent taxonomic revisions have placed the dollar spot fungal pathogens in the new genus Clarireedia, with five species described. The main goal of this study was to develop a quantitative real-time PCR (qPCR) molecular detection assay based on the internal transcribed spacer (ITS) of the ribosomal RNA genes to quantify the abundance of Clarireedia spp. from environmental (field) samples. The qPCR assay was able to detect isolates of the four tested Clarireedia spp. but did not cross react with nontarget fungi, including closely related taxa, other turfgrass pathogens, or other fungal species commonly isolated from turfgrass. The assay is capable of detecting as little as 38.0 fg (3.8 × 10-14 g) of Clarireedia genomic DNA in 3 h. The qPCR assay detected Clarireedia spp. in both symptomatic and asymptomatic creeping bentgrass (Agrostis stolonifera) foliar tissue. Clarireedia spp. were rarely detected in the thatch or soil, indicating that these pathogens are not widely distributed in these areas of the environment. The fact that the pathogen was detected in asymptomatic tissue suggests that creeping bentgrass may be able to tolerate a certain quantity of the pathogens in leaves before disease symptoms appear; however, further research is needed to validate this hypothesis.
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Affiliation(s)
- Glen Groben
- Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901, U.S.A
| | - Bruce B Clarke
- Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901, U.S.A
| | - James Murphy
- Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901, U.S.A
| | - Paul Koch
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, U.S.A
| | - Jo Anne Crouch
- Mycology and Nematology Genetic Diversity and Biology Laboratory, United States Department of Agriculture-Agricultural Research Service, 10300 Baltimore Avenue, Beltsville, MD 20705, U.S.A
| | - Sangkook Lee
- Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901, U.S.A
- Department of Biotechnology, Hoseo University, 20 Hoseo-Ro, 79 Beon-Gil, Baebang-Eup Asan, Chungnam 31499, South Korea
| | - Ning Zhang
- Department of Plant Biology, Rutgers University, New Brunswick, NJ 08901, U.S.A
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901 U.S.A
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Cheng X, Man X, Wang Z, Liang L, Zhang F, Wang Z, Liu P, Lei B, Hao J, Liu X. Fungicide SYP-14288 Inducing Multidrug Resistance in Rhizoctonia solani. PLANT DISEASE 2020; 104:2563-2570. [PMID: 32762501 DOI: 10.1094/pdis-01-20-0048-re] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Rhizoctonia solani is a widely distributed soilborne plant pathogen, and can cause significant economic losses to crop production. In chemical controls, SYP-14288 is highly effective against plant pathogens, including R. solani. To examine the sensitivity to SYP-14288, 112 R. solani isolates were collected from infected rice plants. An established baseline sensitivity showed that values of effective concentration for 50% growth inhibition (EC50) ranged from 0.0003 to 0.0138 μg/ml, with an average of 0.0055 ± 0.0030 μg/ml. The frequency distribution of the EC50 was unimodal and the range of variation factor (the ratio of maximal over minimal EC50) was 46.03, indicating that all wild-type strains were sensitive to SYP-14288. To examine the risk of fungicide resistance, 20 SYP-14288-resistant mutants were generated on agar plates amended with SYP-14288. Eighteen mutants remained resistant after 10 transfers, and their fitness was significantly different from the parental strain. All of the mutants grew more slowly but showed high virulence to rice plants, though lower than the parental strain. A cross-resistance assay demonstrated that there was a positive correlation between SYP-14288 and fungicides having or not having the same mode of action with SYP-14288, including fluazinam, fentin chloride, fludioxonil, difenoconazole, cyazofamid, chlorothalonil, and 2,4-dinitrophen. This result showed a multidrug resistance induced by SYP-14288, which could be a concern in increasing the spectrum of resistance in R. solani to commonly used fungicides.
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Affiliation(s)
- Xingkai Cheng
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Xuejing Man
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Zitong Wang
- College of Plant Protection, Northwest A&F University, Yangling 712100, China
| | - Li Liang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Fan Zhang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Zhiwen Wang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Pengfei Liu
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Bin Lei
- Institute of Nuclear and Biological Technologies, Xinjiang Academy of Agricultural Sciences, 403 Nanchang Road, Urumqi 830091, China
| | - Jianjun Hao
- School of Food and Agriculture, University of Maine, Orono, ME 04469, U.S.A
| | - Xili Liu
- College of Plant Protection, Northwest A&F University, Yangling 712100, China
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Miyamoto T, Hayashi K, Okada R, Wari D, Ogawara T. Resistance to succinate dehydrogenase inhibitors in field isolates of Podosphaera xanthii on cucumber: Monitoring, cross-resistance patterns and molecular characterization. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2020; 169:104646. [PMID: 32828365 DOI: 10.1016/j.pestbp.2020.104646] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/22/2020] [Accepted: 06/25/2020] [Indexed: 06/11/2023]
Abstract
New succinate dehydrogenase inhibitor fungicides (SDHIs), isopyrazam, pyraziflumid and isofetamid were introduced in the Japanese market in 2017-2018 to control powdery mildew on cucumber. SDHI resistance of the disease fungus (Podosphaera xanthii) was first reported during 2008-2009 against boscalid. Then, penthiopyrad which belongs to SDHIs was introduced in 2010, but subsequent monitoring study was not performed. We investigated the sensitivity of P. xanthii field isolates from Ibaraki Prefecture, Japan, to SDHIs and SdhB, SdhC and SdhD gene mutations, using a leaf disc assay and SDH gene analysis. A total of 19 out of the 22 selected isolates showed resistance to SDHIs. The 19 isolates were phenotypically categorized into three types: Resistant I as moderately and Resistant II as highly resistant to penthiopyrad, isopyrazam and pyraziflumid but sensitive to isofetamid and Resistant III as highly resistant to isofetamid but sensitive to the other three SDHIs. SDH gene analysis revealed that Resistant I and III isolates carried a substitution in PxD-S121P and PxC-A86V, respectively. Resistant II carried three different substitutions: PxC-G151R, PxC-G172D, and PxD-H137R. Among 127 isolates sampled from 16 cucumber greenhouses, 54 exhibited Resistant I phenotype and carried only PxD-S121P. Fifty-six isolates exhibited Resistant II and carried PxC-G151R (four isolates), PxC-G172D (24), and PxD-H137R (28). Only two isolates expressed the Resistant III phenotype carrying PxC-A86V. To the best of our knowledge, this is the first report demonstrating cross-resistance patterns and the molecular characterization of SDHIs in P. xanthii.
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Affiliation(s)
- Takuya Miyamoto
- Horticultural Research Institute, Ibaraki Agricultural Centre, 3165-1 Ago, Kasama, Ibaraki 312-0292, Japan.
| | - Kanako Hayashi
- Horticultural Research Institute, Ibaraki Agricultural Centre, 3165-1 Ago, Kasama, Ibaraki 312-0292, Japan.
| | - Ryo Okada
- Horticultural Research Institute, Ibaraki Agricultural Centre, 3165-1 Ago, Kasama, Ibaraki 312-0292, Japan.
| | - David Wari
- Horticultural Research Institute, Ibaraki Agricultural Centre, 3165-1 Ago, Kasama, Ibaraki 312-0292, Japan.
| | - Takashi Ogawara
- Horticultural Research Institute, Ibaraki Agricultural Centre, 3165-1 Ago, Kasama, Ibaraki 312-0292, Japan.
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23
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Multiple mutations across the succinate dehydrogenase gene complex are associated with boscalid resistance in Didymella tanaceti in pyrethrum. PLoS One 2019; 14:e0218569. [PMID: 31220147 PMCID: PMC6586343 DOI: 10.1371/journal.pone.0218569] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Accepted: 06/04/2019] [Indexed: 11/19/2022] Open
Abstract
Failures in control of tan spot of pyrethrum, caused by Didymella tanaceti, has been associated with decreased sensitivity within the pathogen population to the succinate dehydrogenase inhibitor (SDHI) fungicide boscalid. Sequencing the SdhB, SdhC, and SdhD subunits of isolates with resistant and sensitive phenotypes identified 15 mutations, resulting in three amino acid substitutions in the SdhB (H277Y/R, I279V), six in the SdhC (S73P, G79R, H134R, H134Q, S135R and combined H134Q/S135R), and two in the SdhD (D112E, H122R). In vitro testing of their boscalid response and estimation of resistance factors (RF) identified isolates with wild-type (WT) Sdh genotypes were sensitive to boscalid. Isolates with SdhB-I279V, SdhC-H134Q and SdhD-D112E exhibited moderate resistance phenotypes (10 ≥ RF < 100) and isolates with SdhC-H134R exhibited very high resistance phenotypes (RF ≥ 1000). All other substitutions were associated with high resistance phenotypes (100 ≥ RF < 1000). High-resolution melt assays were designed and used to estimate the frequencies of substitutions in four field populations (n = 774) collected in August (pre-boscalid application) and November (post-boscalid application) 2012. The SdhB-H277Y, SdhC-H134R and SdhB-H277R genotypes were most frequently observed across populations at 56.7, 19.0, and 10.3%, respectively. In August 92.9% of D. tanaceti contained a substitution associated with decreased sensitivity. Following boscalid application, this increased to 98.9%, with no WT isolates detected in three fields. Overlaying previously obtained microsatellite and mating-type data revealed that all ten recurrent substitutions were associated with multiple genotypes. Thus, boscalid insensitivity in D. tanaceti appears widespread and not associated with clonal spread of a limited pool of individuals.
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Outwater CA, Proffer TJ, Rothwell NL, Peng J, Sundin GW. Boscalid Resistance in Blumeriella jaapii: Distribution, Effect on Field Efficacy, and Molecular Characterization. PLANT DISEASE 2019; 103:1112-1118. [PMID: 30995420 DOI: 10.1094/pdis-09-18-1555-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cherry leaf spot (CLS), caused by the fungus Blumeriella jaapii, is a major disease of tart cherry (Prunus cerasus L.) trees, leading to early defoliation that results in uneven ripening and poor fruit quality in the current season, reduced fruit set in the following season, and increased potential for winter injury and tree death. Pristine (BASF Corporation, Research Triangle Park, NC), a commonly used fungicide for CLS management in Michigan, is a premix of boscalid, a succinate dehydrogenase inhibitor, and pyraclostrobin, a quinone outside inhibitor. Reduced efficacy of Pristine for CLS control was observed in field trials and commercial orchards and highlights the importance of fungicide resistance monitoring. A total of 1,189 isolates from 31 commercial orchards in Michigan, 111 isolates from nontreated trees (four locations in Michigan and two locations in Ohio), and 133 isolates from a research orchard were collected during 2010, 2011, and 2012 and assayed on boscalid-amended media at concentrations ranging from 0 to 25 μg ml-1. Because of the very slow growth rate of B. jaapii in culture, we determined the minimum inhibitory concentration (MIC) of boscalid as opposed to the effective concentration that inhibits mycelial growth to 50% of the control. Isolates from nontreated trees had MIC values ranging from 0.1 to 0.5 μg ml-1; the MIC of isolates from commercial orchards ranged from 0.1 to >25 μg ml-1, and isolates from the research orchard ranged from 2.5 to >25 μg ml-1. Isolates with MIC values ≥25 μg ml-1 were considered boscalid resistant and comprised 0% of the nontreated isolates, 30.4% of the commercial isolates, and 42.1% of the research orchard isolates. Sequencing of the sdhB gene of resistant isolates led to the detection of the amino acid mutation H260R, which is known to confer boscalid resistance in other phytopathogenic fungi. Our results indicate that the occurrence of the H260R mutation in Michigan populations of B. jaapii is correlated with the reduction in sensitivity to boscalid observed in commercial orchards.
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Affiliation(s)
- Cory A Outwater
- 1 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Tyre J Proffer
- 1 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
- 2 Department of Biological Sciences, Kent State University, Salem, OH 44460; and
| | - Nikki L Rothwell
- 3 Northwest Michigan Horticultural Research Center, Traverse City, MI 49684
| | - Jingyu Peng
- 1 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - George W Sundin
- 1 Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824
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Hu J, Zhou Y, Gao T, Geng J, Dai Y, Ren H, Lamour K, Liu X. Resistance risk assessment for fludioxonil in Sclerotinia homoeocarpa in China. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2019; 156:123-128. [PMID: 31027571 DOI: 10.1016/j.pestbp.2019.02.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 01/23/2019] [Accepted: 02/11/2019] [Indexed: 06/09/2023]
Abstract
Sclerotinia homoeocarpa causes dollar spot disease on turfgrass and is a serious problem on many species worldwide. Fludioxonil, a phenylpyrrole fungicide, is not currently registered for dollar spot control in China. In this study, the baseline sensitivity to fludioxonil was established using an in vitro assay for 105 isolates of S. homoeocarpa collected from 10 locations in different regions of China. Results indicate that the frequency distribution of effective concentration for 50% inhibition of mycelial growth (EC50) values of the S. homoeocarpa isolates was unimodal (W = 0.9847, P = .2730). The mean EC50 value was 0.0020 ± 0.0006 μg/ml with a range from 0.0003 to 0.0035 μg/ml. A total of 7 fludioxonil-resistant mutants were obtained in laboratory, the mutants were stable in fludioxonil sensitivity after the 10th transfer, with resistance factor (RF) ranging from 4.320 to >13,901.4. The mutants showed a positive cross-resistance between fludioxonil and the dicarboximide fungicide iprodione, but not propiconazole, fluazinam, and thiophanate-methyl. When mycelial growth rate, pathogenicity and osmotic sensitivity were assessed, the mutants decreased in the fitness compared with their parental isolates. Sequence alignment of the histidine kinase gene Shos1 revealed a 13-bp fragment deletion only in one mutant, no mutations were observed on Shos1 in the rest resistant mutants.
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Affiliation(s)
- Jian Hu
- College of Agro-grassland Science, Nanjing Agricultural University, Nanjing 210095, PR China.
| | - Yuxin Zhou
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Tao Gao
- College of Agro-grassland Science, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Jiamei Geng
- College of Agro-grassland Science, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Yuan Dai
- College of Agro-grassland Science, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Haiyan Ren
- College of Agro-grassland Science, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Kurt Lamour
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville 37996, USA
| | - Xili Liu
- Department of Plant Pathology, China Agricultural University, Beijing 100193, PR China
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Sang H, Popko JT, Jung G. Evaluation of a Sclerotinia homoeocarpa Population with Multiple Fungicide Resistance Phenotypes Under Differing Selection Pressures. PLANT DISEASE 2019; 103:685-690. [PMID: 30702386 DOI: 10.1094/pdis-06-18-1080-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Dollar spot, caused by Sclerotinia homoeocarpa, is one of the most significant diseases of cool-season turfgrass on golf courses. Resistance to the benzimidazole, dicarboximide, and succinate dehydrogenase inhibitor (SDHI) classes and reduced sensitivity to the sterol-demethylation inhibitor (DMI) in S. homoeocarpa populations have been widely reported in the United States. Moreover, the occurrence of S. homoeocarpa populations with multiple fungicide resistance (MFR) is a growing problem on golf courses. The present study was undertaken to evaluate the efficacy of DMI, dicarboximide, and SDHI against a S. homoeocarpa population with MFR on a Connecticut golf course fairway from 2014 to 2016. Also, because the S. homoeocarpa population consisted of four different phenotypes with differing resistance profiles to benzimidazole, dicarboximide, and DMI, in vitro sensitivity assays were used to understand the dynamics of the MFR population in the presence and absence of fungicide selection pressures. Results indicated that boscalid fungicide (SDHI) was able to provide an acceptable control of the MFR dollar spot population. Propiconazole or iprodione application selected isolates with both DMI and dicarboximide resistance (DMI-R/Dicar-R). In the absence of fungicide selection pressures, the percent frequency of DMI-R/Dicar-R or DMI and benzimidazole resistance (DMI-R/Ben-R) isolates declined in the population. Out of the four phenotypes, the percent frequency of isolates with DMI, dicarboximide, and benzimidazole resistance (DMI-R/Dicar-R/Ben-R) was the lowest in the population regardless of fungicide selection pressures. Our first report of MFR population dynamics will help develop effective strategies for managing MFR and potentially delay the emergence of future resistant populations in S. homoeocarpa.
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Affiliation(s)
- Hyunkyu Sang
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003
| | - James T Popko
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003
| | - Geunhwa Jung
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003
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Sang H, Witte A, Jacobs JL, Chang HX, Wang J, Roth MG, Chilvers MI. Fluopyram Sensitivity and Functional Characterization of SdhB in the Fusarium solani Species Complex Causing Soybean Sudden Death Syndrome. Front Microbiol 2018; 9:2335. [PMID: 30327645 PMCID: PMC6174223 DOI: 10.3389/fmicb.2018.02335] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 09/12/2018] [Indexed: 11/25/2022] Open
Abstract
The succinate dehydrogenase inhibitor (SDHI) fungicide, fluopyram, is used as a soybean seed treatment to manage Fusarium virguliforme, the casual agent of sudden death syndrome (SDS). More recently, other species within clade 2 of the Fusarium solani species, F. tucumaniae in South America and F. brasiliense in America and Africa, have been recognized as additional agents capable of causing SDS. To determine if fluopyram could be used for management of SDS caused by these species, in vitro sensitivity tests of the three Fusarium species to fluopyram were conducted. The mean EC50 values of F. brasiliense and F. virguliforme strains to fluopyram were 1.96 and 2.21 μg ml-1, respectively, but interestingly F. tucumaniae strains were highly sensitive (mean EC50 = 0.25 μg ml-1) to fluopyram compared to strains of the other two species. A sequence analysis of Sdh genes of Fusarium strains revealed that the F. tucumaniae strains contain an arginine at codon 277 in the SdhB gene instead of a glycine as in other Fusarium species. Replacement of glycine to arginine in SdhB-277 in a F. virguliforme wild-type strain Mont-1 through genetic transformation resulted in increased sensitivity to two SDHI fungicides, fluopyram and boscalid. Similar to a F. tucumaniae strain, the Mont-1 (SdhBG277R) mutant caused less SDS and root rot disease than Mont-1 on soybean seedlings with the fluopyram seed treatment. Our study suggests the amino acid difference in the SdhB in F. tucumaniae results in fluopyram being efficacious if used as a seed treatment for management of F. tucumaniae, which is the most abundant SDS causing species in South America. The establishment of baseline sensitivity of Fusarium species to fluopyram will contribute to effective strategies for managing Fusarium diseases in soybean and other pathosystems such as dry bean.
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Affiliation(s)
- Hyunkyu Sang
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, United States
| | - Alexander Witte
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, United States
| | - Janette L. Jacobs
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, United States
| | - Hao-Xun Chang
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, United States
| | - Jie Wang
- Department of Plant Biology, Michigan State University, East Lansing, MI, United States
| | - Mitchell G. Roth
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, United States
- Genetics Graduate Program, Michigan State University, East Lansing, MI, United States
| | - Martin I. Chilvers
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, United States
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Sang H, Hulvey JP, Green R, Xu H, Im J, Chang T, Jung G. A Xenobiotic Detoxification Pathway through Transcriptional Regulation in Filamentous Fungi. mBio 2018; 9:e00457-18. [PMID: 30018104 PMCID: PMC6050962 DOI: 10.1128/mbio.00457-18] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 06/22/2018] [Indexed: 12/12/2022] Open
Abstract
Fungi are known to utilize transcriptional regulation of genes that encode efflux transporters to detoxify xenobiotics; however, to date it is unknown how fungi transcriptionally regulate and coordinate different phases of detoxification system (phase I, modification; phase II, conjugation; and phase III, secretion). Here we present evidence of an evolutionary convergence between the fungal and mammalian lineages, whereby xenobiotic detoxification genes (phase I coding for cytochrome P450 monooxygenases [CYP450s] and phase III coding for ATP-binding cassette [ABC] efflux transporters) are transcriptionally regulated by structurally unrelated proteins. Following next-generation RNA sequencing (RNA-seq) analyses of a filamentous fungus, Sclerotinia homoeocarpa, the causal agent of dollar spot on turfgrasses, a multidrug resistant (MDR) field strain was found to overexpress phase I and III genes, coding for CYP450s and ABC transporters for xenobiotic detoxification. Furthermore, there was confirmation of a gain-of-function mutation of the fungus-specific transcription factor S. homoeocarpa XDR1 (ShXDR1), which is responsible for constitutive and induced overexpression of the phase I and III genes, resulting in resistance to multiple classes of fungicidal chemicals. This fungal pathogen detoxifies xenobiotics through coordinated transcriptional control of CYP450s, biotransforming xenobiotics with different substrate specificities and ABC transporters, excreting a broad spectrum of xenobiotics or biotransformed metabolites. A Botrytis cinerea strain harboring the mutated ShXDR1 showed increased expression of phase I (BcCYP65) and III (BcatrD) genes, resulting in resistance to fungicides. This indicates the regulatory system is conserved in filamentous fungi. This molecular genetic mechanism for xenobiotic detoxification in fungi holds potential for facilitating discovery of new antifungal drugs and further studies of convergent and divergent evolution of xenobiotic detoxification in eukaryote lineages.IMPORTANCE Emerging multidrug resistance (MDR) in pathogenic filamentous fungi is a significant threat to human health and agricultural production. Understanding mechanisms of MDR is essential to combating fungal pathogens; however, there is still limited information on MDR mechanisms conferred by xenobiotic detoxification. Here, we report for the first time that overexpression of phase I drug-metabolizing monooxygenases (cytochrome P450s) and phase III ATP-binding cassette efflux transporters is regulated by a gain-of-function mutation in the fungus-specific transcription factor in the MDR strains of the filamentous plant-pathogenic fungus Sclerotinia homoeocarpa This study establishes a novel molecular mechanism of MDR through the xenobiotic detoxification pathway in filamentous fungi, which may facilitate the discovery of new antifungal drugs to control pathogenic fungi.
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Affiliation(s)
- Hyunkyu Sang
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts, USA
| | - Jonathan P Hulvey
- Department of Biology, Eastern Connecticut State University, Willimantic, Connecticut, USA
| | - Robert Green
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts, USA
| | - Hao Xu
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
| | - Jeongdae Im
- Department of Civil Engineering, Kansas State University, Manhattan, Kansas, USA
| | - Taehyun Chang
- School of Ecology and Environmental System, Kyungpook National University, Sangju, South Korea
| | - Geunhwa Jung
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts, USA
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