山西省番茄早疫病菌对苯醚甲环唑的敏感性及抗性突变体的适合度

Sensitivity of early blight pathogen Alternaria solani to difenoconazole and fitness of resistant mutants

为了解山西省番茄早疫病菌Alternaria solani对苯醚甲环唑的抗性,采用菌丝生长速率法检测了该病菌对苯醚甲环唑的敏感性,分析了抗性水平和抗性指数;同时通过室内诱导获得了苯醚甲环唑抗性突变体,检测了突变体的抗性遗传稳定性、交互抗性和适合度。结果表明:分离自大同、忻州、长治、晋中和运城5市的101株菌株的EC50范围为0.005～3.315 mg/L,均值为0.428 mg/L,其中敏感菌株占97.03%,低抗菌株占2.97%;抗性指数范围为0.295～0.447,均值为0.343。10株中抗突变体抗性均不能稳定遗传、生长速率减慢、产孢量降低、孢子萌发能力减弱、致病力下降;但在药剂压力下,突变体的致病力强于敏感菌株。苯醚甲环唑与代森锰锌、多抗霉素、啶酰菌胺无交互抗性,而与啶菌噁唑存在交互抗性。因此,今后需加强番茄早疫病菌对苯醚甲环唑的田间抗性监测,在生产过程中轮用或混用不同作用机制的药剂以延缓该病菌对苯醚甲环唑抗性的发展。

To understand the resistant situation of early blight pathogen Alternaria solani to difenoconazole in Shanxi Province, the sensitivity to difenoconazole were tested, and the resistance level and the resistance index were analyzed. Also, the difenoconazole-resistant mutants, which were induced in the laboratory, were studied on the genetic stability of resistance, the cross-resistance and the fitness. The results showed that the EC50 values of 101 isolates from Datong, Xinzhou, Changzhi, Jinzhong, and Yuncheng cities ranged from 0.005 to 3.315 mg/L with the mean value of 0.428 mg/L. Among these isolates, 97.03% showed sensitive to difenoconazole, and 2.97% isolates had low resistance. The resistance index ranged from 0.295 to 0.447 with the mean value of 0.343. Ten mutants with medium resistance to difenoconazole were derived from induction in the laboratory, but the resistance couldn’t be inherited steadily. And their mycelial growth, sporulation, spore germination, and pathogenicity were declined. The pathogenicity of mutants was better than that of sensitive isolates under the stress of difenoconazole. No cross-resistance was detected between difenoconazole and mancozeb, polyoxin, or boscalid, excluding pyrisoxazole. Therefore, the sensitivity of A. solani to difenoconazole should be monitored continuously in future, and the mixed or rotated application of fungicides with different mechanism should be considered to postpone the development of resistance.