抗氟吡菌胺辣椒疫霉菌株的诱导及其生物学特性的研究

 采用菌丝生长速率法, 测定了采自泰安、平谷、杭州和昆明4个地区的42株辣椒疫霉病菌对氟吡菌胺的敏感性, 结果表明, 其EC₅₀值在0.618 ~0.927 μg·mL^-1之间, 平均EC₅₀ =(0.743±0.067 7) μg·mL^-1。 42个菌株对氟吡菌胺的敏感性分布呈单峰曲线, 未出现抗性的病原菌亚群体, 可将其单峰曲线作为辣椒疫霉对氟吡菌胺的敏感性基线。采用药剂驯化和紫外照射对辣椒疫霉敏感菌株TA进行诱变处理, 获得了2株辣椒疫霉抗氟吡菌胺菌株;利用菌落直径法测定抗氟吡菌胺菌株的遗传稳定性、菌丝生长速率及对其它杀菌剂的交互抗性;通过活体叶盘法测定抗氟吡菌胺菌株和敏感菌株的致病力及产孢子囊能力, 分析抗性和敏感菌株之间生物学特性差异。结果表明, 敏感菌株TA经过氟吡菌胺 48代连续汰选, 其抗性达58.0倍, 获得中抗菌株TA-R;紫外照射获得了抗性达260.6倍的高抗菌株TA-UV, 且其抗性均能稳定遗传;TA-R和TA-UV对甲霜灵、霜脲氰表现出正交互抗性, 对烯酰吗啉、百菌清、代森锰锌和丙森锌无交互抗性;抗氟吡菌胺菌株TA-R、TA-UV与敏感菌株在活体叶盘上的致病力、离体产孢能力均差异不显著(P＜0.05), 但其菌丝生长速率、菌丝干重均低于敏感菌株。

Induction and charcteristics of Phytophthora capsici isolates resistant to fluopicolide

The sensitivity to fluopicolide of 42 Phytophthora capsici strains collected from Taian, Pinggu, Hangzhou and Kunming were determined by mycelia growth inhibition method. The results showed that EC₅₀ values ranged from 0.618-0.927 μg·mL^-1 with a mean of 0.743±0.067 7 μg·mL^-1. The sensitivity frequency of P. capsici to fluopicolide distributed as a unimodel curve, which showed there was no resistant subpopulation among these isolates, so this sensitivity baseline was suitable for resistance monitoring of P. capsici to fluopicolide. The two fluopicolide-resistant mutants were selected by UV-irradiating and fungicide-selection. Genetic stability, mycelium growth rate and cross-resistance to other fungicides of the resistant strains were determined by measuring the colony diameters, differences of virulence and sporangium production between the sensitive and resistant strains were measured by leaf disk in vivo. The results showed that the resistance of the induced P. capsici isolate TA-R to fluopicolide reached 58.0 folds after 48 times selection compared with the sensitive strain, while the resistance ratios of the mutant that inducted by UV-irradiating reached up to 260.6. The resistant levels of two resistant mutants were stable. The TA-R and TA-UV exhibited positive cross resis-tance to metalaxyl and cymoxanil, while negligible cross resistance to dimethomorph, chlorothalonil, mancozeb and propineb. The differences in virulence and sporulation between resistant strains and TA weren't significant, however, the growth rates and dry-weights of mycelium of two resistant mutants were lower than that of the sensitive(P＜0.05).