马尾松林中球孢白僵菌寄主转移和专化性的SSR标记分析

球孢白僵菌是一种最常见的虫生真菌,已被广泛应用于害虫生物防治。利用SSR简单序列重复(simple sequence repeat,SSR)分子标记对来自安徽省麻姑山马尾松林的102株球孢白僵菌进行基因分型、寄主转移和寄主专化性研究。9对微卫星引物将102株白僵菌分成31个微卫星基因型。在这31个微卫星基因型中,有5种基因型株系为相对优势菌株,这5种基因型株系通过侵染不同寄主昆虫即寄主转移延续自身在马尾松林生态系统中的传播和流行,从而证实寄主转移是白僵菌群体中的普遍现象。同时,这些相对优势基因型并不是在各个月份均匀分布,在大部分月份中,存在1–2种优势度高的基因型。相同基因型株系可侵染不同寄主的结果揭示出白僵菌不仅在种的水平,而且在菌株水平上寄主专化性也较弱。正是白僵菌较弱的寄主专化性特征促使部分基因型株系通过寄主转移,在马尾松林生态系统中得以宿存和延续。

Host shift and host specificity analysis of Beauveria bassiana in Masson's pine plantation based on SSR molecular marker

Beauveria bassiana is one of the most common species of entomopathogenic fungi and widely used in insect pest biocontrol. Multilocus microsatellite genotyping, host shift and host specificity analysis of 102 Beauveria bassiana isolates from Magu Mountains of Anhui Province were detected using SSR molecular markers. Thirty-one multilocus microsatellite genotypes were determined from 102 B. bassiana isolates with 9 pairs of loci primers. Five of thirty-one genotypes possess a higher level of relative dominance. The anniversary host shift dynamics revealed that the 5 multilocus microsatellite genotypes continued their spread and epidemicity in the local Masson’s pine plantation ecosystem by infecting different host,further confirming that host shift is a common phenomenon in B. bassiana population. Meanwhile, these relative dominance genotypes were not evenly distributed in all year round, but in most months, only one or two higher dominant genotypes existed. The results of identical genotype infecting different host inscets revealed B. bassiana display less strict host specificity not only at the species level, but also in the isolates level. It is the less strict host specificity characteristics of B. bassiana that prompted some genotypes to survived and continued by host shift in a pine forest ecosystem.