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Mao Y, Qiu H, Gao X, Li Y, Zheng X, Cai Y, Sheng G, Shen Y, Wang J, Zhou M, Duan Y. Resistance Risk and Molecular Mechanism of Tomato Wilt Pathogen Fusarium oxysporum f. sp. lycopersici to Pyraclostrobin. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:3998-4007. [PMID: 38372233 DOI: 10.1021/acs.jafc.3c09907] [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: 02/20/2024]
Abstract
Tomato wilt disease caused by Fusarium oxysporum f. sp. lycopersici (Fol) results in a decrease in tomato yield and quality. Pyraclostrobin, a typical quinone outside inhibitor (QoI), inhibits the cytochrome bc1 complex to block energy transfer. However, there is currently limited research on the effectiveness of pyraclostrobin against Fol. In this study, we determined the activity of pyraclostrobin against Fol and found the EC50 values for pyraclostrobin against 100 Fol strains (which have never been exposed to QoIs before). The average EC50 value is 0.3739 ± 0.2413 μg/mL, indicating a strong antifungal activity of pyraclostrobin against Fol, as shown by unimodal curves of the EC50 values. Furthermore, we generated five resistant mutants through chemical taming and identified four mutants with high-level resistance due to the Cytb-G143S mutation and one mutant with medium-level resistance due to the Cytb-G137R mutation. The molecular docking results indicate that the Cytb-G143S or Cytb-G137R mutations of Fol lead to a change in the binding mode of Cytb to pyraclostrobin, resulting in a decrease in affinity. The resistant mutants exhibit reduced fitness in terms of mycelial growth (25 and 30 °C), virulence, and sporulation. Moreover, the mutants carrying the Cytb-G143S mutation suffer a more severe fitness penalty compared to those carrying the Cytb-G137R mutation. There is a positive correlation observed among azoxystrobin, picoxystrobin, fluoxastrobin, and pyraclostrobin for resistant mutants; however, no cross-resistance was detected between pyraclostrobin and pydiflumetofen, prochloraz, or cyazofamid. Thus, we conclude that the potential risk of resistance development in Fol toward pyraclostrobin can be categorized as ranging from low to moderate.
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Affiliation(s)
- Yushuai Mao
- College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
- Sanya Institute, Nanjing Agricultural University, Sanya 572025, China
| | - Hui Qiu
- College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
- Sanya Institute, Nanjing Agricultural University, Sanya 572025, China
| | - Xinlong Gao
- College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
| | - Yige Li
- College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
| | - Xuanming Zheng
- College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
| | - Yiqiang Cai
- College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
| | - Guilin Sheng
- Institute for the Control of Agrochemicals Jiangsu Province, Nanjing 210036, China
| | - Yingchun Shen
- Institute for the Control of Agrochemicals Jiangsu Province, Nanjing 210036, China
| | - Jianxin Wang
- College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
| | - Mingguo Zhou
- College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
| | - Yabing Duan
- College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing 210095, China
- Sanya Institute, Nanjing Agricultural University, Sanya 572025, China
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Huang YH, Wei G, Wang WJ, Liu Z, Yin MX, Guo WM, Zhu XL, Yang GF. Structure-Based Discovery of New Succinate Dehydrogenase Inhibitors via Scaffold Hopping Strategy. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:18292-18300. [PMID: 37738510 DOI: 10.1021/acs.jafc.3c02158] [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: 09/24/2023]
Abstract
Scaffold hopping strategy has become one of the most successful methods in the process of molecular design. Seeking to develop novel succinate dehydrogenase inhibitors (SDHIs), we employed a scaffold hopping strategy to design compounds featuring geminate dichloralkenes (gem-dichloralkenes) fragment. After stepwise modifications, a series of N-cyclopropyl-dichloralkenes-pyrazole-carboxamide derivatives was synthesized. Among them, compounds G28 (IC50 = 26.00 nM) and G40 (IC50 = 27.00 nM) were identified as the best inhibitory activity against porcine SDH, with IC50 values reaching the nanomolar range, outperforming the lead compound pydiflumetofen. Additionally, the greenhouse assay indicated that compounds G37 (EC90 = 0.031 mg/L) and G34 (EC90 = 1.67 mg/L) displayed extremely high activities against wheat powdery mildew (WPM) and cucumber powdery mildew (CPM), respectively. Computational results further revealed that the gem-dichloralkene fragment and fluorine substituted pyrazole form an extra hydrophobic interaction and dipolar-dipolar interaction with SDH. In summary, our study provides a novel gem-dichloralkene scaffold with outstanding fungicidal properties, obtained through scaffold hopping, that holds great potential for future research on PM control.
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Affiliation(s)
- Yuan-Hui Huang
- National Key Laboratory of Green Pesticide, Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health of Ministry of Science and Technology, Central China Normal University, Wuhan 430079, People's Republic of China
| | - Ge Wei
- National Key Laboratory of Green Pesticide, Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health of Ministry of Science and Technology, Central China Normal University, Wuhan 430079, People's Republic of China
| | - Wen-Jie Wang
- National Key Laboratory of Green Pesticide, Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health of Ministry of Science and Technology, Central China Normal University, Wuhan 430079, People's Republic of China
| | - Zheng Liu
- National Key Laboratory of Green Pesticide, Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health of Ministry of Science and Technology, Central China Normal University, Wuhan 430079, People's Republic of China
| | - Mao-Xue Yin
- National Key Laboratory of Green Pesticide, Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health of Ministry of Science and Technology, Central China Normal University, Wuhan 430079, People's Republic of China
| | - Wei-Min Guo
- National Key Laboratory of Green Pesticide, Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health of Ministry of Science and Technology, Central China Normal University, Wuhan 430079, People's Republic of China
| | - Xiao-Lei Zhu
- National Key Laboratory of Green Pesticide, Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health of Ministry of Science and Technology, Central China Normal University, Wuhan 430079, People's Republic of China
| | - Guang-Fu Yang
- National Key Laboratory of Green Pesticide, Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, International Joint Research Center for Intelligent Biosensor Technology and Health of Ministry of Science and Technology, Central China Normal University, Wuhan 430079, People's Republic of China
- Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300071, People's Republic of China
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White NH, Neves DL, Nuckles EM, Vaillancourt LJ, Zhang J, Zhang G, Bradley CA. Identification of Quinone Outside Inhibitor Fungicide-Resistant Isolates of Parastagonospora nodorum from Illinois and Kentucky. PLANT DISEASE 2023; 107:38-45. [PMID: 35722914 DOI: 10.1094/pdis-01-22-0180-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
Stagonospora leaf and glume blotch, caused by Parastagonospora nodorum, is a major disease of winter wheat (Triticum aestivum) in the United States capable of significantly reducing grain yield and quality. Pathogens such as P. nodorum that overwinter in crop residue are often an increased concern in cropping systems that utilize no-till farming. In addition, the lack of wheat cultivars with complete resistance to P. nodorum has led to the reliance on foliar fungicides for disease management. Quinone outside inhibitor (QoI) fungicides (Fungicide Resistance Action Committee group 11) are one of the major classes used to manage foliar diseases in wheat. Use of the QoI class of fungicides tends to select isolates of fungal pathogens with resistance due to mutations in the fungal cytochrome b gene. Isolates of P. nodorum were collected from Illinois in 2014 and Kentucky in 2018, 2019, and 2020. Amplification and sequencing of a segment of the cytochrome b gene from these isolates revealed a mutation at codon 143 that confers a change from glycine to alanine in the amino acid sequence (known as the G143A mutation). In vitro plate assays and greenhouse trials were used to confirm and characterize the QoI resistance caused by the G143A mutation. The frequency of the tested isolates with the G143A mutation was 46% (57 of 123 isolates) and 5% (3 of 60 isolates) for Kentucky and Illinois, respectively. This research is the first to identify the G143A mutation in P. nodorum isolates with resistance to QoI fungicides in Illinois and Kentucky.
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Affiliation(s)
- Nathaniel H White
- Department of Plant Pathology, University of Kentucky, Princeton, KY 42445
| | - Danilo L Neves
- Department of Plant Pathology, University of Kentucky, Princeton, KY 42445
| | - Etta M Nuckles
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546
| | | | - Jiawen Zhang
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Guirong Zhang
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Carl A Bradley
- Department of Plant Pathology, University of Kentucky, Princeton, KY 42445
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Marin MV, Seijo TE, Zuchelli E, Peres NA. Detection and Characterization of Quinone Outside Inhibitor-Resistant Phytophthora cactorum and P. nicotianae Causing Leather Rot in Florida Strawberry. PLANT DISEASE 2022; 106:1203-1208. [PMID: 34813708 DOI: 10.1094/pdis-08-21-1658-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Phytophthora cactorum and P. nicotianae cause leather rot (LR) of fruit and Phytophthora crown rot (PhCR) in strawberry. LR occurs sporadically but can cause up to 70% fruit loss when weather is conducive. In Florida's annual strawberry winter production system, PhCR can be severe, resulting in plant stunting, mortality, and severe yield loss. Azoxystrobin is labeled for control of LR but not for PhCR. The aims of this research were to determine the sensitivity of P. cactorum and P. nicotianae isolates from strawberry to azoxystrobin and to investigate mechanisms of quinone-outside-inhibitor resistance present in P. cactorum and P. nicotianae based on the known point mutations within the cytochrome b (cytb) gene. Isolates of both Phytophthora spp. causing LR and PhCR were collected from multiple strawberry fields in Florida between 1997 and 2020. Isolates were tested for sensitivity to azoxystrobin at 0, 0.01, 0.1, 1.0, 10, and 50 μg/ml on potato dextrose agar amended with salicylhydroxamic acid (100 μg/ml). Isolates were separated into two groups - sensitive isolates with the 50% effective concentration (EC50) values <1.0 μg/ml, and resistant isolates having EC50 values >50 μg/ml. P. cactorum and P. nicotianae resistance to azoxystrobin was found for isolates collected after 2010. The first 450 nucleotides of the mitochondrial cytb gene were sequenced from a selection of resistant and sensitive isolates of both species. The G143A mutation reported to confer resistance to azoxystrobin was found in all resistant P. cactorum isolates. However, in P. nicotianae, qualitative resistance was observed, but the isolates lacked all the known mutations in the cytb gene. This is the first report of resistance to azoxystrobin in P. cactorum and P. nicotianae.
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Affiliation(s)
- Marcus V Marin
- Department of Plant Pathology, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598
| | - Teresa E Seijo
- Department of Plant Pathology, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598
| | - Elias Zuchelli
- University of Tennessee Institute of Agriculture, Knoxville, TN 37996
| | - Natalia A Peres
- Department of Plant Pathology, Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598
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Cowger C, Meyers E, Whetten R. Sensitivity of the U.S. Wheat Powdery Mildew Population to Quinone Outside Inhibitor Fungicides and Determination of the Complete Blumeria graminis f. sp. tritici Cytochrome b Gene. PHYTOPATHOLOGY 2022; 112:249-260. [PMID: 34156265 DOI: 10.1094/phyto-04-21-0132-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: 06/13/2023]
Abstract
Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici, is managed primarily with cultivar resistance and foliar fungicides. Quinone outside inhibitors (QoIs), which target the mitochondrial cytochrome b (cytb) gene, are one of the two main fungicide classes used on wheat. While European populations of B. graminis f. sp. tritici are widely insensitive to QoIs, largely because of the cytb mutation G143A, the QoI sensitivity of the U.S. B. graminis f. sp. tritici population had never been evaluated despite years of QoI use on U.S. wheat. A total of 381 B. graminis f. sp. tritici isolates from 15 central and eastern U.S. states were screened for sensitivity to QoI fungicides pyraclostrobin and picoxystrobin. A modest range of sensitivities was observed, with maximum resistance factors of 11.2 for pyraclostrobin and 5.3 for picoxystrobin. The F129L, G137R, and G143A cytb mutations were not detected in the U.S. B. graminis f. sp. tritici population, nor were mutations identified in the PEWY loop, a key part of the Qo site. Thus, no genetic basis for the observed quantitative variation in QoI sensitivity of U.S. B. graminis f. sp. tritici was identified. Isolate sporulation was weakly negatively associated with reduced QoI sensitivity, suggesting a fitness cost. In the course of the study, the complete B. graminis f. sp. tritici cytb gene sequence was determined for the first time in the isolate 96224 v. 3.16 reference genome. Contrary to previous reports, the gene has an intron that appears to belong to intron group II, which is unusual in fungi. The study was the first QoI sensitivity screening of a large, geographically diverse set of U.S. B. graminis f. sp. tritici isolates, and while the population as a whole remains relatively sensitive, some quantitative loss of efficacy was observed.
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Affiliation(s)
- Christina Cowger
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695
- Agricultural Research Service, U.S. Department of Agriculture, Raleigh, NC 27695
| | - Emily Meyers
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695
| | - Rebecca Whetten
- Agricultural Research Service, U.S. Department of Agriculture, Raleigh, NC 27695
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Peng Q, Zhao H, Zhao G, Gao X, Miao J, Liu X. Resistance assessment of pyraoxystrobin in Magnaporthe oryzae and the detection of a point mutation in cyt b that confers resistance. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2022; 180:105006. [PMID: 34955180 DOI: 10.1016/j.pestbp.2021.105006] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/30/2021] [Accepted: 12/04/2021] [Indexed: 06/14/2023]
Abstract
Pyraoxystrobin is a new QoI fungicide developed in China. The present study was aimed at determining the baseline sensitivity of M. oryzae to pyraoxystrobin and investigating the potential resistance risk and resistance mechanism of pyraoxystrobin in M. oryzae. The results showed that the mean EC50 of 109 M. oryzae isolates to pyraoxystrobin was 0.0094 μg/mL and the sensitivity exhibited a unimodal distribution. The established baseline sensitivity could provide critical data for monitoring sensitivity changes of M. oryzae to pyraoxystrobin in rice fields. The potential resistance risk was assessed by investigating the biological characteristics of the resistant mutants obtained by fungicide adaptation. The results indicated that the resistance risk of pyraoxystrobin in M. oryzae was medium to high with positive cross-resistance between pyraoxystrobin and azoxystrobin, but without cross resistance between pyraoxystrobin and carbendazim, isoprothiolane, and prochloraz. Further investigation revealed that the pyraoxystrobin-resistant mutants had a G143S mutation in the cyt b protein. Molecular docking confirmed that the G143S substitution conferred high resistance to pyraoxystrobin in M. oryzae. Collectively, the results of this study provided essential data for monitoring the emergence of resistance and developing resistance management strategies for pyraoxystrobin.
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Affiliation(s)
- Qin Peng
- State Key Laboratory of Crop Stress Biology for Arid Arears, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Hua Zhao
- State Key Laboratory of Crop Stress Biology for Arid Arears, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Guosen Zhao
- State Key Laboratory of Crop Stress Biology for Arid Arears, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Xuheng Gao
- State Key Laboratory of Crop Stress Biology for Arid Arears, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China
| | - Jianqiang Miao
- State Key Laboratory of Crop Stress Biology for Arid Arears, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China.
| | - Xili Liu
- State Key Laboratory of Crop Stress Biology for Arid Arears, College of Plant Protection, Northwest A&F University, 3 Taicheng Road, Yangling 712100, Shaanxi, China; Department of Plant Pathology, College of Plant Protection, China Agricultural University, 2 Yuanmingyuan Road, Beijing 100193, China.
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Cinget B, Bélanger RR. Discovery of new group I-D introns leads to creation of subtypes and link to an adaptive response of the mitochondrial genome in fungi. RNA Biol 2020; 17:1252-1260. [PMID: 32449459 PMCID: PMC7595605 DOI: 10.1080/15476286.2020.1763024] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Group I catalytic introns are widespread in bacterial, archaeal, viral, organellar, and some eukaryotic genomes, where they are reported to provide regulatory functions. The group I introns are currently divided into five types (A-E), which are themselves distributed into several subtypes, with the exception of group I type D intron (GI-D). GI-D introns belong to the rarest group with only 17 described to date, including only one with a putative role reported in fungi, where it would interfere with an adaptive response in the cytochrome b (COB) gene to quinone outside inhibitor (QoI) fungicide resistance. Using homology search methods taking into account both conserved sequences and RNA secondary structures, we analysed the mitochondrial genomes or COB genes of 169 fungal species, including some frequently under QoI selection pressure. These analyses have led to the identification of 216 novel GI-D introns, and the definition of three distinct subtypes, one of which being linked with a functional activity. We have further uncovered a homing site for this GI-D intron type, which helps refine the accepted model of quinone outside inhibitor resistance, whereby mobility of the intron across fungal mitochondrial genomes, would influence a fungus ability to develop resistance to QoIs.
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Affiliation(s)
- Benjamin Cinget
- Département de Phytologie, Faculty of Agriculture and Food Sciences, Centre de Recherche en Innovation des Végétaux (CRIV), Université Laval , Québec, Québec, Canada
| | - Richard R Bélanger
- Département de Phytologie, Faculty of Agriculture and Food Sciences, Centre de Recherche en Innovation des Végétaux (CRIV), Université Laval , Québec, Québec, Canada
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Xiang Y, Miller AN, McGrath M, Babadoost M. Genotyping-by-Sequencing for Analysis of the Genetic Variation of Podosphaera xanthii, Incitant of Cucurbit Powdery Mildew. PLANT DISEASE 2020; 104:951-957. [PMID: 31891549 DOI: 10.1094/pdis-03-19-0513-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This research was conducted to identify species causing powdery mildew on cucurbits and to determine genetic variations among isolates of the pathogen. We collected 109 isolates from six cucurbit species hosts (Cucumis melo, Cucumis sativus, Cucurbita maxima, Cucurbita moschata, Cucurbita pepo, and Lagenaria siceraria) in California, Illinois, Indiana, Michigan, New York, Texas, Washington, and Wisconsin in the United States and in Italy. By sequencing the internal transcribed spacer region of the nuclear rDNA of these 109 isolates, Podosphaera xanthii was found as the only species causing powdery mildew on cucurbits in the United States. Genotyping-by-sequencing was applied to these 109 isolates to investigate their genetic diversity, which showed a trend of isolates clustering from New York and Italy. In addition, the virulence of 36 isolates was compared and a significant difference (P < 0.0001) was found among them. Furthermore, results of the virulence tests of 28 isolates from Illinois showed significant effects of collection years, hosts, and locations on the virulence of the isolates.
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Affiliation(s)
- Y Xiang
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - A N Miller
- Illinois Natural History Survey, University of Illinois, Champaign, IL 61820
| | - M McGrath
- Cornell University, Riverhead, NY 11901
| | - M Babadoost
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
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Vielba-Fernández A, de Vicente A, Pérez-García A, Fernández-Ortuño D. Monitoring Methyl Benzimidazole Carbamate-Resistant Isolates of the Cucurbit Powdery Mildew Pathogen, Podosphaera xanthii, Using Loop-Mediated Isothermal Amplification. PLANT DISEASE 2019; 103:1515-1524. [PMID: 31059385 DOI: 10.1094/pdis-12-18-2256-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Powdery mildew, caused by the fungus Podosphaera xanthii, is one of the most economically important diseases affecting cucurbit crops in Spain. Currently, chemical control offers the most efficient management of the disease; however, P. xanthii isolates resistant to multiple classes of site-specific fungicides have been reported in the Spanish cucurbit powdery mildew population. In previous studies, resistance to the fungicides known as methyl benzimidazole carbamates (MBCs) was found to be caused by the amino acid substitution E198A on β-tubulin. To detect MBC-resistant isolates in a faster, more efficient, and more specific way than the traditional methods used to date, a loop-mediated isothermal amplification (LAMP) system was developed. In this study, three sets of LAMP primers were designed. One set was designed for the detection of the wild-type allele and two sets were designed for the E198A amino acid change. Positive results were only obtained with both mutant sets; however, LAMP reaction conditions were only optimized with primer set 2, which was selected for optimal detection of the E198A amino acid change in P. xanthii-resistant isolates, along with the optimal temperature and duration parameters of 65°C for 75 min, respectively. The hydroxynaphthol blue (HNB) metal indicator was used for quick visualization of results through the color change from violet to sky blue when the amplification was positive. HNB was added before the amplification to avoid opening the lids, thus decreasing the probability of contamination. To confirm that the amplified product corresponded to the β-tubulin gene, the LAMP product was digested with the enzyme LweI and sequenced. Our results show that the LAMP technique is a specific and reproducible method that could be used for monitoring MBC resistance of P. xanthii directly in the field.
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Affiliation(s)
- Alejandra Vielba-Fernández
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain; and Departamento de Microbiología, Instituto de Hortofruticultura Subtropical y Mediterránea, "La Mayora" Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Campus de Teatinos, 29071 Málaga, Spain
| | - Antonio de Vicente
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain; and Departamento de Microbiología, Instituto de Hortofruticultura Subtropical y Mediterránea, "La Mayora" Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Campus de Teatinos, 29071 Málaga, Spain
| | - Alejandro Pérez-García
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain; and Departamento de Microbiología, Instituto de Hortofruticultura Subtropical y Mediterránea, "La Mayora" Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Campus de Teatinos, 29071 Málaga, Spain
| | - Dolores Fernández-Ortuño
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain; and Departamento de Microbiología, Instituto de Hortofruticultura Subtropical y Mediterránea, "La Mayora" Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Campus de Teatinos, 29071 Málaga, Spain
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Chechi A, Stahlecker J, Dowling ME, Schnabel G. Diversity in species composition and fungicide resistance profiles in Colletotrichum isolates from apples. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2019; 158:18-24. [PMID: 31378355 DOI: 10.1016/j.pestbp.2019.04.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 04/04/2019] [Indexed: 06/10/2023]
Abstract
Outbreaks of bitter rot were observed in three commercial apple orchards in Illinois despite best management efforts during the 2018 production season. Three isolates from symptomatic fruit from these orchards and two isolates from an orchard in South Carolina were identified to the species level using morphological tools and calmodulin, glyceraldehyde-3-phosphate dehydrogenase, and beta-tubulin gene sequences. The isolates from Illinois were identified as Colletotrichum siamense of the Colletotrichum gloeosporioides species complex and the ones from South Carolina as Colletotrichum fioriniae and Colletotrichum fructicola of the Colletotrichum acutatum and the C. gloeosporioides species complex, respectively. Two of the three C. siamense isolates from Illinois were resistant to azoxystrobin and thiophanate-methyl as determined in mycelial growth tests in vitro. EC50 values were >100 μg/ml for both fungicides. One isolate was only resistant to azoxystrobin. None of the isolates from South Carolina was resistant to either of the two compounds. All five isolates were sensitive to fludioxonil (EC50 values <0.1 μg/ml), propiconazole (EC50 values ranged from 0.15 to 0.36 μg/ml), and benzovindiflupyr (EC50 values ranged from <0.1 to 0.33 μg/ml). Resistance in C. siamense to azoxystrobin and thiophanate-methyl was confirmed in detached fruit studies using apples treated with label rates of registered product. Resistance to thiophanate-methyl in C. siamense was based on E198A mutation in b-tubulin gene, whereas resistance to azoxystrobin was based on G143A in cytochrome b (CYTB). One isolate resistant to azoxystrobin possessed no amino acid variation in CYTB. This study shows that quinone outside inhibitor fungicide resistance in Colletotrichum from apple has emerged and is being selected for in Illinois apple orchards by current spray strategies. Resistance monitoring may alert growers to potential threats, but the employment of molecular tools based on current knowledge of resistance mechanisms will provide incomplete results.
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Affiliation(s)
- A Chechi
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, United States of America
| | - J Stahlecker
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, United States of America
| | - M E Dowling
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, United States of America
| | - G Schnabel
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, United States of America.
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Yin WX, Adnan M, Shang Y, Lin Y, Luo CX. Sensitivity of Botrytis cinerea From Nectarine/Cherry in China to Six Fungicides and Characterization of Resistant Isolates. PLANT DISEASE 2018; 102:2578-2585. [PMID: 30299208 DOI: 10.1094/pdis-02-18-0244-re] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Botrytis cinerea, the causal agent of gray mold, can result in considerable preharvest and postharvest losses in many economically valuable plant species. Fungicides were widely used to minimize such losses, but fungicide resistances were detected frequently. In the present study, we collected 164 isolates from nectarine and cherry in China and tested the sensitivity to six fungicides. Among the tested isolates, 71 (43.3%) were resistant to azoxystrobin, 14 (8.5%) to cyprodinil, 7 (4.3%) to boscalid, 4 (2.4%) to carbendazim, 1 (0.6%) to iprodione, and no isolates were found to be resistant to fludioxonil. The EC50 value and resistance factor (RF) of resistant isolates were determined. Fitness analysis showed that there were no significant differences between sensitive and resistant isolates for osmotic stress and pathogenicity, while more conidia production was observed for some resistant isolates. Control efficacy of fungicides showed that the resistant isolates could not be controlled efficiently by using corresponding fungicides. The point mutation G143A was detected in the Cyt b gene of the isolates resistant to azoxystrobin, while the point mutation H272R of SdhB gene was confirmed in boscalid-resistant isolates, and mutations E198V/A of TUB2 gene and mutation I365S of BcOs1 occurred in carbendazim-resistant and iprodione-resistant isolates, respectively. These results indicate that the occurrence of fungicide resistance greatly threatens the management of gray mold on stone fruits nectarine and cherry.
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Affiliation(s)
- W X Yin
- Key Lab of Horticultural Plant Biology, Ministry of Education, College of Plant Science and Technology and Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
| | - M Adnan
- Key Lab of Horticultural Plant Biology, Ministry of Education, College of Plant Science and Technology and Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
| | - Y Shang
- Key Lab of Horticultural Plant Biology, Ministry of Education, College of Plant Science and Technology and Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
| | - Y Lin
- Key Lab of Horticultural Plant Biology, Ministry of Education, College of Plant Science and Technology and Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
| | - C X Luo
- Key Lab of Horticultural Plant Biology, Ministry of Education, College of Plant Science and Technology and Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan 430070, China
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12
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Bolnick DI, Barrett RD, Oke KB, Rennison DJ, Stuart YE. (Non)Parallel Evolution. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2018. [DOI: 10.1146/annurev-ecolsys-110617-062240] [Citation(s) in RCA: 155] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Parallel evolution across replicate populations has provided evolutionary biologists with iconic examples of adaptation. When multiple populations colonize seemingly similar habitats, they may evolve similar genes, traits, or functions. Yet, replicated evolution in nature or in the laboratory often yields inconsistent outcomes: Some replicate populations evolve along highly similar trajectories, whereas other replicate populations evolve to different extents or in distinct directions. To understand these heterogeneous outcomes, biologists are increasingly treating parallel evolution not as a binary phenomenon but rather as a quantitative continuum ranging from parallel to nonparallel. By measuring replicate populations’ positions along this (non)parallel continuum, we can test hypotheses about evolutionary and ecological factors that influence the extent of repeatable evolution. We review evidence regarding the manifestation of (non)parallel evolution in the laboratory, in natural populations, and in applied contexts such as cancer. We enumerate the many genetic, ecological, and evolutionary processes that contribute to variation in the extent of parallel evolution.
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Affiliation(s)
- Daniel I. Bolnick
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
- Current affiliation: Department of Ecology and Evolution, University of Connecticut, Storrs, Connecticut 06268, USA
| | | | - Krista B. Oke
- Redpath Museum, McGill University, Montreal, Quebec H3A 2K6, Canada
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California 95060, USA
| | - Diana J. Rennison
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Yoel E. Stuart
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas 78712, USA
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Ma D, Jiang J, He L, Cui K, Mu W, Liu F. Detection and Characterization of QoI-Resistant Phytophthora capsici Causing Pepper Phytophthora Blight in China. PLANT DISEASE 2018; 102:1725-1732. [PMID: 30125205 DOI: 10.1094/pdis-01-18-0197-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Phytophthora capsici is a highly destructive plant pathogen that has spread worldwide. To date, the quinone outside inhibitor (QoI) azoxystrobin has been the choice of farmers for managing this oomycete. In this study, the sensitivity of 90 P. capsici isolates collected from Yunnan, Fujian, Jiangxi, Zhejiang, and Guangdong in southern China to azoxystrobin was assessed based on mycelial growth, sporangia formation, and zoospore discharge. Furthermore, the mitochondrial cytochrome b (cytb) gene from azoxystrobin-sensitive and -resistant P. capsici isolates was compared to investigate the mechanism of QoI resistance. The high values for effective concentration to inhibit 50% of mycelial growth and large variation factor obtained provide strong support for the existence of azoxystrobin-resistant subpopulations in wild populations. The resistance frequency of P. capsici to azoxystrobin was greater than 40%. Sensitive P. capsici isolates were strongly suppressed on V8 medium plates containing azoxystrobin supplemented with salicylhydroxamic acid at 50 µg ml-1, whereas resistant isolates grew well under these conditions. Multiple alignment analysis revealed a missense mutation in the cytb gene that alters codon 137 (GGA to AGA), causing an amino acid substitution of glycine to arginine (G137R). The fitness of the azoxystrobin-sensitive isolate is similar to that of the G137R mutant. Additionally, the P. capsici isolates used in this study exhibited decreased sensitivity to two other QoI fungicides (pyraclostrobin and famoxadone). Necessary measures should be taken to control this trend of resistance to QoI that has developed in P. capsici in southern China.
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Affiliation(s)
- Dicheng Ma
- Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Jiangong Jiang
- Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Leiming He
- Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Kaidi Cui
- Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Wei Mu
- Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Tai'an, Shandong 271018, China
| | - Feng Liu
- Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Tai'an, Shandong 271018, China
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Vielba-Fernández A, Bellón-Gómez D, Torés JA, de Vicente A, Pérez-García A, Fernández-Ortuño D. Heteroplasmy for the Cytochrome b Gene in Podosphaera xanthii and its Role in Resistance to QoI Fungicides in Spain. PLANT DISEASE 2018; 102:1599-1605. [PMID: 30673427 DOI: 10.1094/pdis-12-17-1987-re] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In Spain, management of the cucurbit powdery mildew pathogen Podosphaera xanthii is strongly dependent on chemicals such as quinone outside inhibitor (QoI) fungicides. In a previous report, widespread resistance to QoI fungicides in populations of P. xanthii in south-central Spain was documented, but the molecular mechanisms of resistance remained unclear. In this work, the role of the Rieske-FeS (risp) and the cytochrome b (cytb) gene mutations in QoI resistance of P. xanthii were examined. No point mutations in the risp gene were found in the three QoI-resistant isolates analyzed. For cytb, sequence analysis revealed the presence of a G143A substitution that occurs in many QoI-resistant fungi. This mutation was always detected in QoI-resistant isolates of P. xanthii; however, it was also detected in sensitive isolates. To better understand the role of heteroplasmy for cytb in QoI resistance of P. xanthii, an allele-specific quantitative PCR was developed to quantify the relative abundance of the G143 (sensitive) and A143 (resistant) alleles. High relative abundance of A143 allele (70%) was associated with isolates resistant to QoI fungicides; however, QoI-sensitive isolates also carried the mutated allele in frequencies ranged from 10 to 60%. Our data suggest that G143A mutation in cytb is the primary factor involved in QoI resistance of P. xanthii but the proportion of G143 and A143 alleles in an isolate may determine its QoI resistance level.
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Affiliation(s)
- Alejandra Vielba-Fernández
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga - Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Estación Experimental "La Mayora", 29750 Algarrobo-Costa (Málaga), Spain
| | - Davinia Bellón-Gómez
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga - Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Estación Experimental "La Mayora", 29750 Algarrobo-Costa (Málaga), Spain
| | - Juan A Torés
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora", Universidad de Málaga - Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Estación Experimental "La Mayora", 29750 Algarrobo-Costa (Málaga), Spain
| | - Antonio de Vicente
- IHSM-UMA-CSIC, Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
| | - Alejandro Pérez-García
- IHSM-UMA-CSIC, Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
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15
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Esser L, Zhou F, Zhou Y, Xiao Y, Tang WK, Yu CA, Qin Z, Xia D. Hydrogen Bonding to the Substrate Is Not Required for Rieske Iron-Sulfur Protein Docking to the Quinol Oxidation Site of Complex III. J Biol Chem 2016; 291:25019-25031. [PMID: 27758861 DOI: 10.1074/jbc.m116.744391] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/05/2016] [Indexed: 11/06/2022] Open
Abstract
Complex III or the cytochrome (cyt) bc1 complex constitutes an integral part of the respiratory chain of most aerobic organisms and of the photosynthetic apparatus of anoxygenic purple bacteria. The function of cyt bc1 is to couple the reaction of electron transfer from ubiquinol to cytochrome c to proton pumping across the membrane. Mechanistically, the electron transfer reaction requires docking of its Rieske iron-sulfur protein (ISP) subunit to the quinol oxidation site (QP) of the complex. Formation of an H-bond between the ISP and the bound substrate was proposed to mediate the docking. Here we show that the binding of oxazolidinedione-type inhibitors famoxadone, jg144, and fenamidone induces docking of the ISP to the QP site in the absence of the H-bond formation both in mitochondrial and bacterial cyt bc1 complexes, demonstrating that ISP docking is independent of the proposed direct ISP-inhibitor interaction. The binding of oxazolidinedione-type inhibitors to cyt bc1 of different species reveals a toxophore that appears to interact optimally with residues in the QP site. The effect of modifications or additions to the toxophore on the binding to cyt bc1 from different species could not be predicted from structure-based sequence alignments, as demonstrated by the altered binding mode of famoxadone to bacterial cyt bc1.
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Affiliation(s)
- Lothar Esser
- From the Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Fei Zhou
- From the Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Yihui Zhou
- From the Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.,the College of Science, China Agricultural University, Beijing 100193, China, and
| | - Yumei Xiao
- From the Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.,the College of Science, China Agricultural University, Beijing 100193, China, and
| | - Wai-Kwan Tang
- From the Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Chang-An Yu
- the Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma 74078
| | - Zhaohai Qin
- the College of Science, China Agricultural University, Beijing 100193, China, and
| | - Di Xia
- From the Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892,
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16
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Fujimura M, Banno S, Kamei M, Ishigami Y, Tsukada Y. Detection and monitoring of fungicide resistance in plant pathogens using pyrosequencing. ACTA ACUST UNITED AC 2016. [DOI: 10.1584/jpestics.w15-36] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Shinpei Banno
- Japan Plant Protection Association, Yamanashi Experiment Station
| | - Masayuki Kamei
- The University of Georgia, Department of Microbiology, Athens
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Genetic diversity analysis of the cucurbit powdery mildew fungus Podosphaera xanthii suggests a clonal population structure. Fungal Biol 2015; 119:791-801. [DOI: 10.1016/j.funbio.2015.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 05/07/2015] [Accepted: 05/11/2015] [Indexed: 11/22/2022]
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18
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Moore AL, Shiba T, Young L, Harada S, Kita K, Ito K. Unraveling the heater: new insights into the structure of the alternative oxidase. ANNUAL REVIEW OF PLANT BIOLOGY 2013; 64:637-63. [PMID: 23638828 DOI: 10.1146/annurev-arplant-042811-105432] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The alternative oxidase is a membrane-bound ubiquinol oxidase found in the majority of plants as well as many fungi and protists, including pathogenic organisms such as Trypanosoma brucei. It catalyzes a cyanide- and antimycin-A-resistant oxidation of ubiquinol and the reduction of oxygen to water, short-circuiting the mitochondrial electron-transport chain prior to proton translocation by complexes III and IV, thereby dramatically reducing ATP formation. In plants, it plays a key role in cellular metabolism, thermogenesis, and energy homeostasis and is generally considered to be a major stress-induced protein. We describe recent advances in our understanding of this protein's structure following the recent successful crystallization of the alternative oxidase from T. brucei. We focus on the nature of the active site and ubiquinol-binding channels and propose a mechanism for the reduction of oxygen to water based on these structural insights. We also consider the regulation of activity at the posttranslational and retrograde levels and highlight challenges for future research.
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Affiliation(s)
- Anthony L Moore
- Biochemistry and Molecular Biology, School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom.
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De Miccolis Angelini RM, Rotolo C, Masiello M, Pollastro S, Ishii H, Faretra F. Genetic analysis and molecular characterisation of laboratory and field mutants of Botryotinia fuckeliana (Botrytis cinerea) resistant to QoI fungicides. PEST MANAGEMENT SCIENCE 2012; 68:1231-1240. [PMID: 22488841 DOI: 10.1002/ps.3281] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 11/28/2011] [Accepted: 01/25/2012] [Indexed: 05/31/2023]
Abstract
BACKGROUND QoI fungicides, inhibitors of mitochondrial respiration, are considered to be at high risk of resistance development. In several phytopathogenic fungi, resistance is caused by mutations (most frequently G143A) in the mitochondrial cytochrome b (cytb) gene. The genetic and molecular basis of QoI resistance were investigated in laboratory and field mutants of Botryotinia fuckeliana (de Bary) Whetz. exhibiting in vitro reduced sensitivity to trifloxystrobin. RESULTS B. fuckeliana mutants highly resistant to trifloxystrobin were obtained in the laboratory by spontaneous mutations in wild-type strains, or from naturally infected plants on a medium amended with 1-3 mg L(-1) trifloxystrobin and 2 mM salicylhydroxamic acid, an inhibitor of alternative oxidase. No point mutations were detected, either in the complete nucleotide sequences of the cytb gene or in those of the aox and Rieske protein genes of laboratory mutants, whereas all field mutants carried the G143A mutation in the mitochondrial cytb gene. QoI resistance was always maternally inherited in ascospore progeny of sexual crosses of field mutants with sensitive reference strains. CONCLUSIONS The G143A mutation in cytb gene is confirmed to be responsible for field resistance to QoIs in B. fuckeliana. Maternal inheritance of resistance to QoIs in progeny of sexual crosses confirmed that it is caused by extranuclear genetic determinants. In laboratory mutants the heteroplasmic state of mutated mitochondria could likely hamper the G143A detection, otherwise other gene(s) underlying different mechanisms of resistance could be involved.
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20
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Samuel S, Papayiannis LC, Leroch M, Veloukas T, Hahn M, Karaoglanidis GS. Evaluation of the incidence of the G143A mutation and cytb intron presence in the cytochrome bc-1 gene conferring QoI resistance in Botrytis cinerea populations from several hosts. PEST MANAGEMENT SCIENCE 2011; 67:1029-1036. [PMID: 21702077 DOI: 10.1002/ps.2226] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 04/29/2011] [Accepted: 05/08/2011] [Indexed: 05/31/2023]
Abstract
BACKGROUND Previous studies have shown that resistance of Botrytis cinerea to QoI fungicides has been attributed to the G143A mutation in the cytochrome b (cytb) gene, while, in a part of the fungal population, an intron has been detected at codon 143 of the gene, preventing QoI resistance. During 2005-2009, 304 grey mould isolates were collected from strawberry, tomato, grape, kiwifruit, cucumber and apple in Greece and screened for resistance to pyraclostrobin and for the presence of the cytb intron, using a novel real-time TaqMan PCR assay developed in the present study. RESULTS QoI-resistant phenotypes existed only within the population collected from strawberries. All resistant isolates possessed the G143A mutation. Differences were observed in the genotypic structure of cytb. Individuals possessing the intron were found at high incidence in apple fruit and greenhouse-grown tomato and cucumber populations, whereas in the strawberry population the intron frequency was lower. Cultivation of QoI-resistant and QoI-sensitive isolates for ten culture cycles on artificial nutrient medium in the presence or absence of fungicide selection showed that QoI resistance was stable. CONCLUSIONS The results of the study suggest that a high risk for selection of QoI-resistant strains exists in crops heavily treated with QoIs, in spite of the widespread occurrence of the cytb intron in B. cinerea populations. The developed real-time TaqMan PCR constitutes a powerful tool to streamline detection of the mutation by reducing pre- and post-amplification manipulations, and can be used for rapid screening and quantification of QoI resistance.
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Affiliation(s)
- Stylianos Samuel
- Plant Pathology Laboratory, Faculty of Agriculture, Aristotelian University, Thessaloniki, Greece
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21
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Albury MS, Elliott C, Moore AL. Ubiquinol-binding site in the alternative oxidase: Mutagenesis reveals features important for substrate binding and inhibition. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1933-9. [DOI: 10.1016/j.bbabio.2010.01.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 01/11/2010] [Accepted: 01/12/2010] [Indexed: 11/16/2022]
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22
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Exploring mechanisms of resistance to respiratory inhibitors in field strains of Botrytis cinerea, the causal agent of gray mold. Appl Environ Microbiol 2010; 76:6615-30. [PMID: 20693447 DOI: 10.1128/aem.00931-10] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Respiratory inhibitors are among the fungicides most widely used for disease control on crops. Most are strobilurins and carboxamides, inhibiting the cytochrome b of mitochondrial complex III and the succinate dehydrogenase of mitochondrial complex II, respectively. A few years after the approval of these inhibitors for use on grapevines, field isolates of Botrytis cinerea, the causal agent of gray mold, resistant to one or both of these classes of fungicide were recovered in France and Germany. However, little was known about the mechanisms underlying this resistance in field populations of this fungus. Such knowledge could facilitate resistance risk assessment. The aim of this study was to investigate the mechanisms of resistance occurring in B. cinerea populations. Highly specific resistance to strobilurins was correlated with a single mutation of the cytb target gene. Changes in its intronic structure may also have occurred due to an evolutionary process controlling selection for resistance. Specific resistance to carboxamides was identified for six phenotypes, with various patterns of resistance levels and cross-resistance. Several mutations specific to B. cinerea were identified within the sdhB and sdhD genes encoding the iron-sulfur protein and an anchor protein of the succinate dehydrogenase complex. Another as-yet-uncharacterized mechanism of resistance was also recorded. In addition to target site resistance mechanisms, multidrug resistance, linked to the overexpression of membrane transporters, was identified in strains with low to moderate resistance to several respiratory inhibitors. This diversity of resistance mechanisms makes resistance management difficult and must be taken into account when developing strategies for Botrytis control.
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López-Ruiz FJ, Pérez-García A, Fernández-Ortuño D, Romero D, García E, de Vicente A, Brown JKM, Torés JA. Sensitivities to DMI fungicides in populations of Podosphaera fusca in south central Spain. PEST MANAGEMENT SCIENCE 2010; 66:801-808. [PMID: 20533378 DOI: 10.1002/ps.1948] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
BACKGROUND Cucurbit powdery mildew elicited by Podosphaera fusca (Fr.) U Braun & N Shishkoff limits crop production in Spain. Disease control is largely dependent on fungicides such as sterol demethylation inhibitors (DMIs). Fungicide resistance is an increasing problem in this pathogen. To overcome such risk, it is necessary to design rational control programmes based upon knowledge of field resistance. The aim of this study was to investigate the state of DMI sensitivity of Spanish P. fusca populations and provide tools for improved disease management. RESULTS Using a leaf-disc assay, sensitivity to fenarimol, myclobutanil and triadimenol of 50 isolates of P. fusca was analysed to determine discriminatory concentrations between sensitive and resistant isolates. As no clearly different groups of isolates could be identified, discriminatory concentrations were established on the basis of maximum fungicide field application rate, 100 mg L(-1) for the three fungicides tested. Subsequently, a survey of DMI resistance was carried out in different provinces located in the south central area of Spain during the cucurbit growing seasons in 2002, 2003 and 2004. Examination of a collection of 250 isolates revealed that 23% were resistant to fenarimol and 7% to triadimenol, the provinces of Almería, Badajoz and Murcia being the locations with the highest frequencies of resistance. By contrast, no resistance to myclobutanil was found. CONCLUSION Results show that fenarimol and, to a lesser extent, triadimenol have become less efficient for controlling cucurbit powdery mildew in Spain. These are important observations that should lead to reconsideration of the current disease management programmes.
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Walker AS, Auclair C, Gredt M, Leroux P. First occurrence of resistance to strobilurin fungicides in Microdochium nivale and Microdochium majus from French naturally infected wheat grains. PEST MANAGEMENT SCIENCE 2009; 65:906-915. [PMID: 19431150 DOI: 10.1002/ps.1772] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
BACKGROUND Microdochium nivale (Fr.) Samuels & Hallet and Microdochium majus (Wollenweber) belong to the Fusarium ear blight (FEB) fungal complex affecting cereals. In 2007 and 2008, major Microdochium sp. infestations were observed in France, and the efficacy of strobilurins was found to be altered in some field trials. The aim of this study was to determine the sensitivity to strobilurins of French isolates of Microdochium and to characterise the possible mechanisms of resistance. RESULTS Half of the strains collected in 2007 were resistant to strobilurins, and most also displayed strong resistance to benzimidazoles. Strobilurin resistance was found mostly in M. majus isolates. Positive cross-resistance was observed between all strobilurins tested, but not with the phenylpyrrole derivative fludioxonil and the various classes of sterol biosynthesis inhibitors (SBIs). In most strains, resistance was correlated with the G143A substitution in cytochrome b, the molecular target of strobilurins. Two other mechanisms were also detected at lower frequencies. CONCLUSION This is the first report of strobilurin resistance in Microdochium. Several resistance mechanisms have evolved independently in populations and may have different impacts on field efficacy. This makes the accurate detection and quantification of QoI resistance difficult. The management of field resistance and efficacy must be adapted to take these findings into account.
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Ishii H, Fountaine J, Chung WH, Kansako M, Nishimura K, Takahashi K, Oshima M. Characterisation of QoI-resistant field isolates of Botrytis cinerea from citrus and strawberry. PEST MANAGEMENT SCIENCE 2009; 65:916-922. [PMID: 19444805 DOI: 10.1002/ps.1773] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
BACKGROUND In 2004, field isolates of Botrytis cinerea Pers. ex Fr., resistant to strobilurin fungicides (QoIs), were first found in commercial citrus orchards in Wakayama Prefecture, Japan. Subsequently, QoI-resistant isolates of this fungus were also detected in plastic strawberry greenhouses in Saga, Ibaraki and Chiba prefectures, Japan. Biological and molecular characterisation of resistant isolates was conducted in this study. RESULTS QoI-resistant isolates of B. cinerea grew well on PDA plates containing kresoxim-methyl or azoxystrobin at 1 mg L(-1), supplemented with 1 mM of n-propyl gallate, an inhibitor of alternative oxidase, whereas the growth of sensitive isolates was strongly suppressed. Results from this in vitro test were in good agreement with those of fungus inoculation tests in vivo. In resistant isolates, the mutation at amino acid position 143 of the cytochrome b gene, known to be the cause of high QoI resistance in various fungal pathogens, was found, but only occasionally. The heteroplasmy of cytochrome b gene was confirmed, and the wild-type sequence often present in the majority of resistant isolates, indicating that the proportion of mutated cytochrome b gene was very low. CONCLUSION The conventional RFLP and sequence analyses of PCR-amplified cytochrome b gene are insufficient for molecular identification of QoI resistance in B. cinerea.
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Affiliation(s)
- Hideo Ishii
- National Institute for Agro-Environmental Sciences, Tsukuba, Ibaraki 305-8604, Japan.
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Pérez-García A, Romero D, Fernández-Ortuño D, López-Ruiz F, De Vicente A, Torés JA. The powdery mildew fungus Podosphaera fusca (synonym Podosphaera xanthii), a constant threat to cucurbits. MOLECULAR PLANT PATHOLOGY 2009; 10:153-60. [PMID: 19236565 PMCID: PMC6640438 DOI: 10.1111/j.1364-3703.2008.00527.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
UNLABELLED Numerous vegetable crops are susceptible to powdery mildew, but cucurbits are arguably the group most severely affected. Podosphaera fusca (synonym Podosphaera xanthii) is the main causal agent of cucurbit powdery mildew and one of the most important limiting factors for cucurbit production worldwide. Although great efforts have been invested in disease control, by contrast, many basic aspects of the biology of P. fusca remain unknown. TAXONOMY Podosphaera fusca (Fr.) Braun & Shishkoff. Kingdom Fungi; Phylum Ascomycota; Subdivision Pezizomycotina; Class Leotiomycetes; Order Erysiphales; Family Erysiphaceae; genus Podosphaera; species fusca. IDENTIFICATION Superficial persistent mycelium. Conidia in chains, hyaline, ellipsoid to ovoid or doliform, about 24-40 x 15-22 microm, with cylindrical or cone-shaped fibrosin bodies, which often germinate from a lateral face and produce a broad, clavate germ tube and cylindrical foot-cells. Unbranched erect conidiophores. Cleistothecia globose, mostly 70-100 microm in diameter, dark brown/black. One ascus per cleistothecium with eight ascospores. HOST RANGE Angiosperm species that include several families, such as Asteracea, Cucurbitaceae, Lamiaceae, Scrophulariaceae, Solanaceae and Verbenaceae. DISEASE SYMPTOMS White colonies develop on leaf surfaces, petioles and stems. Under favourable environmental conditions, the colonies coalesce and the host tissue becomes chlorotic and usually senesces early. CONTROL Chemical control and the use of resistant cultivars. Resistance has been documented in populations of P. fusca to some of the chemicals registered for control.
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Affiliation(s)
- Alejandro Pérez-García
- Grupo de Microbiología y Patología Vegetal-Unidad Asociada al CSIC, Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain.
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Torriani SF, Brunner PC, McDonald BA, Sierotzki H. QoI resistance emerged independently at least 4 times in European populations of Mycosphaerella graminicola. PEST MANAGEMENT SCIENCE 2009; 65:155-62. [PMID: 18833571 DOI: 10.1002/ps.1662] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
BACKGROUND QoI fungicides or quinone outside inhibitors (also called strobilurins) have been widely used to control agriculturally important fungal pathogens since their introduction in 1996. Strobilurins block the respiration pathway by inhibiting the cytochrome bc1 complex in mitochondria. Several plant pathogenic fungi have developed field resistance. The first QoI resistance in Mycosphaerella graminicola (Fuckel) Schroter was detected retrospectively in UK in 2001 at a low frequency in QoI-treated plots. During the following seasons, resistance reached high frequencies across northern Europe. The aim of this study was to identify the main evolutionary forces driving the rapid emergence and spread of QoI resistance in M. graminicola populations. RESULTS The G143A mutation causing QoI resistance was first detected during 2002 in all tested populations and in eight distinct mtDNA sequence haplotypes. By 2004, 24 different mtDNA haplotypes contained the G143A mutation. Phylogenetic analysis showed that strobilurin resistance was acquired independently through at least four recurrent mutations at the same site of cytochrome b. Estimates of directional migration rates showed that the majority of gene flow in Europe had occurred in a west-to-east direction. CONCLUSION This study demonstrated that recurring mutations independently introduced the QoI resistance allele into different genetic and geographic backgrounds. The resistant haplotypes then increased in frequency owing to the strong fungicide selection and spread eastward through wind dispersal of ascospores.
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Affiliation(s)
- Stefano Ff Torriani
- Plant Pathology Group, Institute of Integrative Biology, ETH Zurich/LFW, Universitätstrasse 2, CH-8092 Zurich, Switzerland
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