摘要
【目的】了解华南地区瓜类疫霉(Phytophthora melonis)对甲霜灵的田间抗药性。【方法】2007-2010年从广西、广东两省(区)9个市冬瓜和黄瓜产区采集疫病样品,分离纯化瓜类疫霉,分别采用菌落生长速率法和叶盘漂浮法测定瓜类疫霉对甲霜灵的敏感性,并用药剂驯化方法从敏感性菌株诱导瓜类疫霉抗甲霜灵突变体。【结果】从9个市24个样点共分离纯化获得193株瓜类疫霉,抗药性检测结果表明,敏感菌株、中等抗性菌株和抗性菌株分别占测试菌株的29.0%、18.1%和52.8%;不同地区、不同寄主分离的菌株的抗性频率和抗性水平差异较大,来源于广东的菌株抗性频率和抗性水平一般高于来源广西的菌株,分离自黄瓜的菌株高于分离自冬瓜的菌株,大部分样点抗性菌株占据优势群体,个别菌株的抗性指数高达4226.9,叶盘漂浮法测定结果和菌落生长速率法相似;在含药平板上对敏感菌株进行甲霜灵抗性诱导结果表明,从60%的敏感菌株中成功诱导出对甲霜灵抗性稳定的突变体,突变体的抗性水平为敏感性亲本的189-407倍;9株来源于未施用过甲霜灵等苯基酰胺类杀菌剂样点的菌株均为敏感性菌株,其EC50值为0.0429-0.5461μg/mL,将它们EC50的平均值0.3200±0.1617μg/mL确定为华南地区瓜类疫霉对甲霜灵的敏感性基线;对两个样点的监测结果表明,瓜类疫霉抗甲霜灵菌株的频率及抗性指数有逐年增高趋势。【结论】华南广西和广东两省(区)瓜类疫霉对甲霜灵抗性普遍发生,瓜类疫霉对甲霜灵抗药性产生与其和药剂的接触密切相关。瓜类疫霉敏感性基线的建立,可为今后瓜类疫霉抗甲霜灵的评价和进一步监测提供科学依据。
[Objective] Phytophthora melonis is the casual agent of wax gourd and cucumber Phytophthora blight which becomes a constraint for sustainable production of the related crops.Metalaxyl is one of the principal fungicides for controlling the disease now.The objectives of the present study were：（1） to investigate the baseline sensitivity and field resistance of P.melonis to metalaxyl in South China;（2） to test the occurrence of metalaxyl-resistant mutants from metalaxyl-sensitive wild type strains exposed to the fungicide;and（3） to monitor the development of metalaxyl resistance in P.melonis population.[Methods] Over 400 samples of wax gourd and cucumber Phytophthora blight were collected from Guangxi Zhuang Autonomous Region and Guangdong province during 2007-2010,and 193 strains of P.melonis were isolated and purified.The sensitivity of the isolated strains to metalaxyl was tested using mycelial growth rate method in vitro and floating-leaf-disk method in vivo,respectively.The metalaxyl-sensitive strains were induced on PDA plates containing 10 μg/mL metalaxyl.[Results] The sensitive,moderately resistant and resistant strains were recorded as 29.0%,18.1% and 52.8%,respectively,among 193 tested strains.The frequency and level of resistance of P.melonis from Guangdong were higher than that from Guangxi.The strains from cucumber was generally more resistant to metalaxyl than those from wax gourd.The metalaxyl-resistant strains were frequently detected as predominant populations in most of the sampling sites and the highest resistance index（4226.9） was confirmed.Metalaxyl-resistant（Mrt） mutants could be isolated from approximately 60% of the sensitive wild-type strains.The resistance level of the Mrt mutants was 189-407 times higher than that of their sensitive parental strains.The EC50 values of 9 sensitive strains from a sampling site without a record of phenylamide fungicide application ranged from 0.0429 to 0.5461 μg/mL.Their mean EC50 value（0.3200±0.1617 μg/mL） was considered as the baseline sensitivity of P.melonis to metalaxyl in South China.[Conclusion] Metalaxyl-resistant strains universally occur in South China,especially in the vegetable-growing areas with a longer history of metalaxyl application.The establishment of the baseline sensitivity of P.melonis to metalaxyl will provide a science-based guide for evaluating and further monitoring resistance of the pathogen to the fungicide.
出处
《微生物学报》
CAS
CSCD
北大核心
2011年第8期1078-1086,共9页
Acta Microbiologica Sinica
基金
广西农业科学院科技发展基金(200916)
基本科研业务专项基金项目(201017)
广西区财政厅项目[桂财预函(2008)119号]~~
关键词
瓜类疫霉
甲霜灵
抗药性
敏感性基线
检测
Phytophthora melonis
metalaxyl
fungicide resistance
baseline sensitivity
test
