杨树腐烂病菌表观特征及遗传多样性分析

为探究杨树腐烂病菌的表观特征、遗传多样性以及它们与不同寄主杨树派别和病原菌地理来源的关系，本文收集来自我国14个省份的106份杨树腐烂病标本，纯培养观察记录菌落生长状况，分析菌株培养形态多样性，并从中选取背景信息差异较大的菌株34份，采用SRAP和ISSR两种标记方法分析其遗传多样性。结果显示:杨树腐烂病菌同一菌株在不同条件下的培养性状稳定；不同菌株的培养形态差异明显，且各类别间菌株的培养性状与寄主植物、地理来源没有明显相关性。利用获得多态性良好的12对SRAP引物和20条ISSR引物分析得出群体的Nei's多样性指数为0.31(SRAP)、0.28(ISSR)，各菌株间存在较大的遗传差异；并从寄主角度分析其群体遗传结构，得出群体总的遗传多样性为0.27，群体内的遗传多样性为0.23，可以解释总体多样性的87%，遗传分化系数(G_ST)为0.13，遗传变异主要存在于群体内。从地理角度分析得出，总的群体遗传多样性为0.28，群体内的遗传多样性为0.13，可以解释总体多样性的48%，G_ST为0.52，来自群体内和群体间的多样性差异相当，而地理群体间的迁移对总体的遗传分化产生了较大的影响，各群体的遗传多样性水平表现为从西到东依次降低的趋势。 

Analysis of appearance features and genetic diversity of Cytospora chrysosperma causing poplar canker

In order to investigate the appearance features and genetic diversity of Cytospora chrysosperma, as well as their relationships with different factions of the host poplar and their geographic origin, in this paper, 106 samples of C. chrysosperma from 14 provinces of China were collected and observed. And the growth of strains was recorded when being cultivated to analyze the cultivated morphological diversity of strains. Then, 34 samples with obviously different background information were selected and genetic diversity was analyzed using two signing methods of SRAP and ISSR. The results showed that C. chrysosperma presented stable cultivated traits in the same strain under different conditions. While different strains had obvious morphological differences, but there were no obvious correlations between their cultivated traits and their host plants or geographic origins. 12 SRAP primers and 20 ISSR primers with decent polymorphism were obtained in total, which were used to analyze and calculate Nei's index of the population diversity. The results were 0. 31 ( SRAP) and 0. 28 ( ISSR) , indicating that large genetic differences existed among varied strains. On the other hand, population genetic structure was analyzed from the perspective of the host. The results showed that the total population genetic diversity was 0. 27 and the genetic diversity within population was 0. 23 , which can explain 87% of the overall diversity and the genetic separation coefficient (GST) was 0. 13. All of above showed that the genetic variation mainly existed within the group. From the view of geographical position, the total genetic diversity was 0. 28, genetic diversity within population was 0. 13 , which can explain 48% of overall diversity and the coefficient of genetic separation (GST) was 0. 52. That means the diversity within population is equivalent to that among populations. The geographic migrations among populations have great impacts on the overall genetic separation. The genetic diversity levels of the populations show a decreasing trend from west to east.