两广地区家蚕白僵菌的SSRs遗传多样性

为查明广东和广西地区家蚕Bombyx mori病原白僵菌的来源及其菌株间的相互关系， 本研究利用了微卫星标记（simple sequence repeats， SSRs）技术， 分别对采自广东、 广西蚕区的白僵菌菌株居群之间和居群之内的遗传多态性进行了研究。结果发现， 两广白僵菌居群之间的基因分化系数（Gst）是0.0590， 多态位点百分率（PPL）为97.73%， Nei氏基因多样性指数（H）为0.1896， Shannon氏信息多样性指数（I）为0.3165， 表明两广家蚕来源的白僵菌居群间的遗传分化较小； 两个居群内部的遗传多态性研究结果分别是广东白僵菌居群的PPL=68.18%， H=0.1910， I=0.3044， 而广西白僵菌居群的PPL=65.91%， H=0.1713， I=0.1791， 表明广东白僵菌居群的遗传多样性水平较高， 广西白僵菌居群遗传多样性水平相对较低。最后， 利用Nei氏遗传距离进行了两广地区白僵菌菌株间地理来源关系的聚类分析， 结果表明实验室保存菌株单独聚为类群Ⅰ， 而不同采集地的菌株聚为类群Ⅱ。结果反映了生产来源的白僵菌菌株存在遗传多态性和基因分化现象， 暗示了家蚕白僵病病原来源的复杂性， 还说明应用SSRs技术进行家蚕白僵病病原的溯源是一条可行的途径。

Genetic diversity of Beauveria bassiana in different silkworm populations from Guangdong and Guangxi, southern China, based on SSRs

The genetic diversity of 13 Beauveria bassiana strains in different silkworm (Bombyx mori) populations from Guangdong and Guangxi, southern China, was analyzed based on simple sequence repeats (SSRs). A total of 137 fragments were obtained with 9 SSR primers, on average 15 fragments each primer. Further analysis with POPGEN indicated that the inner-population genetic differentiation (Gst) was 0.0590, the polymorphic rate（PPL） was 97.73%, the Nei’s genetic diversity index (H) was 0.1896, and the Shannon’s information diversity index (I) was 0.3165. The level of genetic variation of Guangdong populations was higher (PPL=68.18%, H=0.1910, I=0.3044), while that of the Guangxi populations (PPL=65.91%, H=0.1713, I=0.1791) is smaller. The result showed that the genetic diversity of B. bassiana Guangdong strains was higher than that of B. bassiana Guangxi strains. The dendrogram of B. bassiana Guangdong and Guangxi strains was constructed by UPGMA cluster analysis based on the Nei’s genetic distance, and it is found that different strains from different collecting localities are divided into two clades. The results indicate that the genetic structure of B. bassiana from Guangdong and Guangxi is very complicated, and there is certain degree of similarity between the strains of Beauveria from the partial silkworm region, suggesting that it is feasible to trace the origin of B. bassiana with SSRs.