【作者】 钱忠海；

【导师】 周明国；

【作者基本信息】 南京农业大学 ， 植物病理学， 2006， 硕士

【摘要】 嘧菌酯（Azoxystrobin）是由先正达公司（原捷利康）开发的，也是第一个商品化的甲氧基丙烯酸酯类杀菌剂，具有杀菌活性高，防病谱广，与环境相容性好等突出优点。甲氧基丙烯酸酯类杀菌剂作用于真菌线粒体电子传递链的复合物Ⅲ，阻断电子传递，干扰能量合成，因其通过与细胞色素b（Cyt b）的Q₀部位结合而称之为Q₀I。由于其独特的作用机制，与已有的所有杀菌剂无交互抗药性。但已有研究表明多种植物病原真菌对该类药剂产生抗药性自发突变频率较高，在高选择压下自然界易形成抗药性病原真菌群体。 辣椒疫病（Phytophthora capsici Leonian）是中国辣椒生产上最严重的土传病害之一。由于传统杀卵菌药剂的长期大量单一使用，田间已经产生了广泛的抗药性，防治效果下降，寻找新型杀菌剂来控制辣椒疫病的流行已成为化学防治工作者的目标。所以研究辣椒疫霉对嘧菌酯的敏感性以及其抗药性风险评估具有重要的现实意义。 本文从未接触过Q₀Is和QiIs的江苏南京和安徽和县地区随机采集分离获得48个辣椒疫霉单游动孢子囊菌株，并测定了它们不同发育阶段对嘧菌酯的敏感性。结果表明，辣椒疫霉菌丝生长阶段对嘧菌酯的敏感性最低，而且分布范围最大，EC₅₀值范围在1.225～86.1μg／mL，平均值为21.041±14.397μg／mL，其活性低于甲霜灵47.7倍；游动孢子囊形成和萌发对嘧菌酯的敏感性较高，EC₅₀值范围分别在0.006～0.996μg／mL和0.053～0.334μg／mL，平均值分别为0.161±0.126μg／mL和0.155±0.023μg／mL，其活性高于甲霜灵516.8倍；游动孢子萌发对嘧菌酯的敏感性最高，EC₅₀值范围在0.018～0.111μg／mL，平均值为0.057±0.011μg／mL，活性是甲霜灵的142.4倍。 通过紫外诱变获得抗嘧菌酯突变体UV-17和H4-V3。两个突变体抗药性状较稳定，菌丝生长速率与亲本菌株无显著差异，产生游动孢子囊的能力在水培的前3d较亲本菌株高，之后较亲本菌株低；但抗药性突变体产生的游动孢子囊释放游动孢子的时间更多还原

【Abstract】 Azoxystrobin, developed by Syngenta (Zeneca) company, was the first product of the strobilurin fungicides. It combines high level and broad-spectrum of fungicidal activity with excellent safety in the environment. Strobilurin fungicides inhibit mitochondrial respiration in fungi at a specific site on complex III and break energy synthesization of fungi. Strobilurins were called QoI as they combined with Qo part of Cyt b. This kind of fungicide was widely used because of their novel action mechanism and non-cross-resistance with . However, the frequency of spontaneous resistant mutation was high according to several research reports. It’s easy to form resistant-population in high fungicidal selection pressure.Pepper blight (Phytophthora capsici Leonian) is one of the most serious diseases on China pepper produce. Aimed to control the popularity of pepper blight, fungicidal workers are searching new fungicides for the widely resistance to traditional Oomycete-fungicides occurred in field. So, it is essential to embark on sensitivity and resistance risk assessment of Phytophthora capsici Leonian to Azoxystrobin.48 single-sporangia isolates of Phytophthora capsici, causing capsicum epidemic disease, were collected and separated from Nanjing, Jiangsu Province and Hexian, Anhui Province where QOIs and Qils had not been used previously. Sensitivities of different morpha of P. capsici life cycle to azoxystrobin were determined. Mycelial growth of P. capsici was least affected by azoxystrobin, with mean EC50 value 21.041 ± 14.397 μg/mL ranging from 1.225 to 86.1 μg/mL. Activity of azoxystrobin EC50 was lower than that of metalaxyl 47.7 times. The mean EC50 values of the azoxystrobin inhibiting sporangia formation and germination of P. capsici were 0.161 ±0.126 μg/mL and 0.155±0.023 μg/mL ranging from 0.006 to 0.996 μg/mL and 0.053 to 0.334 μg/mL, respectively. Its activity was 516.8 folds as that of metalaxyl. Germination of encysted zoospores of P. capsici was most sensitive to azoxystrobin, and EC50 distributed from 0.018 to 0.111 μg/mLwith mean value 0.057±0.011 μg/mL. This value was 142.4 times lower than that of metalaxyl.Mutants UV-17 and H4-V3 of Phytophthora capsici Leonian were gained by更多还原