芒果炭疽病菌对多菌灵的抗药性

Studies on carbendazim-resistance of Colletotrichum gloeosporioides on mango fruit

对来自广东和海南等不同果园的芒果炭疽病菌进行了对多菌灵的抗性测定。结果表明,敏感菌株的最小抑制浓度(MIC)为0.110μg/mL,而抗性菌株在多菌灵500μg/mL 下仍生长良好。抗性菌株经继代培养10代后抗性几乎不变,说明其抗性稳定。对抗、感菌株的生物学特性进行测定,然后以产孢量和致病力分别用 MIC 做简单相关性分析,证明病菌的生物学特性、产孢量、致病力与抗药性无关,因此可以认为病菌对多菌灵的抗药性突变并不影响其正常的生理功能。抗性菌株对甲基硫菌灵、苯菌灵、噻菌灵表现正交互抗性,而对乙霉威和咪鲜胺敏感。病菌在含药培养基上测定的敏感性与在经多菌灵处理过的离体果实上的敏感性有较好的对应关系,可用于大田抗药性的初步检测。

The samples of Colletotrichum gloeosporioides of mango in different orchards were collected and their resistance to carbendazim was tested in vitro.The results showed that the minimal inhibitory concentration (MIC) of sensitive isolates were 0.110μg/mL.However,resistant isolates were able to grow well even on 500μg/mL carbendazim.The resistance to carbendazim was stably inherited after continuously transferred for 10 generations on carbendazim-free PDA medium.Biological characters of resistant and sensitive isolates were tested and compared.The correlation analysis of MIC to no.of conidia produced and pathogenicity were car- ried out and the results showed that these factors were appeared no correlation of resistance to carbendazim. Resistant isolates showed positive cross-resistance to thiophanate-methyl,benomyl,thiabendazole and sensitiv- ity to diethofencarb and prochloraz.The resistant and sensitive isolates were inoculated on mango fruits which were soaked in carbendazim solution in vitro.As a result,the fruits treated with fungicide and then inoculated with resistant isolates still showed disease symptoms as severe as the control,while the fruits inoculated with sensitive ones show no symptoms,which was response to resistant level of the isolates were tested on the PDA medium containing carbendazim.The tests on PDA medium can be used for supervising resistant isolates in the field.