基于SSR标记的琅琊山球孢白僵菌寄主专化性

球孢白僵菌Beauveria bassiana是一类常见的昆虫病原真菌,其自然侵染的寄主昆虫众多,达15目149科750种。为了解球孢白僵菌自然种群的遗传多样性,探讨种群异质性和寄主来源之间的关系,分析其寄主专化性的强弱,本研究利用SSR分子标记技术,比较了安徽琅琊山国家森林公园的85株球孢白僵菌（寄主种类涉及7目24种）群体遗传多样性差异,通过构建聚类树分析菌株基因型和寄主关联性。结果表明琅琊山球孢白僵菌群体Nei’s基因多样性指数h=0.2906,Shannon信息指数I_s=0.4510,多态位点百分率P为100%。不同寄主目球孢白僵菌遗传多样性水平由高至低为鞘翅目>膜翅目>同翅目>双翅目>鳞翅目>直翅目>半翅目,其中菌株数量较多的鞘翅目、膜翅目和同翅目3个亚种群的遗传多样性较高且水平接近。聚类分析发现8对SSR引物将85株球孢白僵菌分成29个基因型,并在遗传相似系数0.70处分别聚为3个分支。分析寄主类型发现相同基因型的株系可侵染不同目的寄主,而同一类型寄主也可被不同基因型的菌株侵染。球孢白僵菌种群的总体遗传多样性较高,遗传谱系与寄主来源无明显相关性,菌株的寄主专化性弱。

Host specificity of Beauveria bassiana isolated from Langya Mountain inferred from SSR marker

As one of the most common entomopathogenic fungi throughout the world, Beauveria bassiana parasitizes diverse insects belonging to 15 orders, 149 families and 750 species. SSR molecular marker technique has been performed to study the genetic diversity in natural population, relationship between population heterogeneity and host range and the host specificity of 85 isolates of B. bassiana parasitic on 24 species in 7 orders of insects from Langya Mountain National Forest Park in Anhui Province. A clustering tree was also constructed to analyze the relationship between genotypes and hosts. The results indicated that Nei’s gene diversity was 0.2906, Shannon’s information index was 0.4510 and the percentage of polymorphic loci was 100% for B. bassiana population in Langya Mountain. The genetic diversity of B. bassiana on different hosts decreased from high to low in the proper order of Coleoptera>Hymenoptera>Homoptera>Diptera> Lepidoptera>Orthoptera>Hemiptera and genetic diversity of subpopulations on Coleoptera, Hymenoptera and Homoptera constituting the majority of isolates showed higher and closer at diversity level. Cluster analysis showed that 85 B. bassiana isolates were divided into 29 genotypes by 8 SSR primers and merged to 3 branches at 0.70 genetic similarity coefficients. Isolates of the same genotype can infect different hosts, and the same type of hosts could also be infected by different genotypes of the fungus. In summary, genetic diversity of B. bassiana population in Langya Mountain was rich and there was no significant correlation between the genetic lineage and host range, and the host specificity of the fungus was weak.