烟草黑胫病菌抗甲霜灵突变体的诱导及其适合度研究

Studies on Induction and Fitness of Metalaxyl-resistant Mutants in Phytophthora nicotianae var.nicotianae

室内离体条件下采用药剂诱导法，获得了11个烟草黑胫病茵抗甲霜灵突变体；检测了所有抗药突变体的抗药稳定性及抗性水平；比较了3个低抗和1个高抗突变体的适合度。结果表明：在2～20μg／mL范围内，抗药突变体的发生频率随甲霜灵诱导浓度的增加而提高；所有抗药突变体的抗药性都能稳定遗传；11个抗药突变体中，10个为低抗突变体（抗性水平3．55-13．9倍，平均8．60倍），1个为高抗突变体（抗性水平510倍）；低抗菌株20M-001、10M-003、10M-006和高抗菌株10M-004的适合度指数分别为0．56、0．38、0．38和0．87；抗药突变体的适合度指数与抗性水平不相关。

Eleven metalaxyl-resistant isolates were obtained from sensitive strain of Phytophthora nicotianae vat. nicotianae on plates containing series concentration of metalaxyl. The stability and levels of resistance for all the resistant isolates were determined;the fitness of 3 low and 1 high level of resistant isolates was compared. The results showed that the occurrence frequency of the resistant isolates increased when metalaxyl concentration increased within the range from 2 μg/mL to 20 μg/mL; the resistance of all the resistant isolates could be maintained stably subculturing on OA plates;the mutants could be classified into two phenotypes of resistance： 10 low resistant isolates, whose resistance levels ranged from 3.55 to 13.9-fold with the average of 8.60, and 1 high resistant isolate, whose resistance level was 510-fold;the fitness index of the low resistant isolates of 20M-001,10M-003,10M-006 and the high resistant isolate of 10M-004, were 0. 56 ,0. 38 ,0. 38 and 0.87, respectively;there was no correlation between the fitness index and the resistance level of the resistant isolates.