浙江衢州地区柑橘绿霉病菌对抑霉唑和多菌灵的抗性水平及其分子机制

研究了采自浙江衢州地区,包括柯城区、衢江区和开化县12个贮藏库的70个柑橘绿霉病菌Penicillium digitatum菌株对抑霉唑和多菌灵的抗性频率、抗性水平及其抗性分子机制。结果表明:柯城区和衢江区的抑霉唑抗性菌株(最低抑制浓度MIC≥0.5 μg/mL)的比例分别为77.1%和62.5%,两地抗性菌株的平均EC50值分别为2.07±1.04 μg/mL和2.35±0.73 μg/mL,分别是当地敏感菌株EC50值的41.4和47.0倍;而采自开化县的菌株均对抑霉唑敏感(MIC≤0.1 μg/mL),平均EC50值为0.04±0.02 μg/mL。柯城区和衢江区的多菌灵抗性菌株(MIC≥10 μg/mL) 的比例分别为54.3%和54.2%,而开化县的抗性菌株比例仅为9.1%。即来自柯城和衢江两个柑橘主产区的绿霉病菌群体对抑霉唑和多菌灵的抗性频率均远高于非柑橘主产区的开化县群体,说明抗药性群体的形成与药剂使用历史有关。进一步研究发现,衢州地区柑橘绿霉病菌对抑霉唑的抗性均属于IMZ-R3型,即与抑霉唑靶标基因 CYP51B 启动子区的插入突变有关,而对多菌灵的抗性则与 β-微管蛋白基因的992位核苷酸点突变(T→A)导致对应的200位点的氨基酸突变(F→Y)有关。

Resistance level and mechanism of Penicillium digitatum to imazalil and carbendazim in Quzhou,Zhejiang

The resistance and their molecular mechanisms of 70 isolates of Penicillium digitatum from 12 citrus store houses in Quzhou city (included Kecheng and Qujiang districts,as well as Kaihua County) to imazalil and carbendazim were studied.The results demonstrated that the frequency of imazalil-resistant isolates μg/mL in Kecheng and Qujiang districts were 77.1% and 62.5%,respectively.The mean EC50 values of imazalil-resistant isolates from Kecheng and Qujiang distracts were 2.07±1.04 μg/mL and 2.35±0.73 μg/mL,respectively,which were 41.4 and 47 times higher than those of imazalil-sensitive isolates (MIC≤0.1 μg/mL).However,no imazalil-resistant isolates was detected in Kaihua,and the mean EC50 values of P.digitatum was 0.04±0.02 μg/mL.The frequencies of carbendazim-resistant isolates (MIC＞10 μg/mL) in Kecheng and Qujiang were 54.3% and 54.2%,whereas 9.1% in Kaihua.These results indicated that the frequencies of imazalil and carbendazim resistance of P.digitatum were much higher in main citrus producing areas (Kecheng and Qujiang districts) than that in non-main citrus producing areas (Kaihua),inferring that the formation of resistant population is associated with the history of fungicide application.Further study showed that the resistance mechanism of P.digitatum from Quzhou was belonged to IMZ-R3,an unique insertion sequence in the promoter region of CYP51B gene,whereas a point mutation at aa200 of β-tubulin gene from phenylalanine (F) to tyrosine (Y),which resulted from the mutation at 992 nt from T to A,was responsible for carbendazim resistance.