东北地区水稻纹枯病菌致病性及遗传多样性分析

Pathogenicity and genetic diversity analysis of Rhizoctonia solani population in northeast China

为明确东北地区水稻纹枯病菌致病性及其群体遗传多样性,将2018年采自东北三省13个水稻主产区的病样分离纯化,共获得176个立枯丝核菌菌株。采用离体叶片接种法测定菌株致病力,利用SRAP分子标记技术分析其遗传多样性。致病力测定结果表明,东北三省各地区菌株致病力存在分化现象,供试的176个菌株中,强致病力菌株占全部菌株23.3%;中等致病力菌株占61.9%;弱致病力菌株占14.8%。地理来源与致病力无明显相关性。根据UPGMA聚类分析,当相似系数为0.63时,176个菌株被划分为6个类群。聚类结果与地理来源具有相关性,但与致病力无明显相关性。利用16对SRAP引物分析176个立枯丝核菌菌株遗传多样性,共得到2 237个扩增条带,多态性频率为82.16%;基因多样度(h)、Shannon信息指数(I)分别为0.2827、0.4150。东北各地区立枯丝核菌群体间遗传距离与地理距离呈一定正相关。群体遗传分化系数Gst=0.3319,基因流Nm=1.0063,说明东北地区立枯丝核菌群体遗传分化度较高且群体间存在基因交流。AMOVA分析结果表明,群体内遗传分化为67.84%,遗传变异主要发生在群体内部。

To ascertain the pathogenicity and genetic diversity of Rhizoctonia solani population, a total of 176 isolates of R. solani were isolated from 13 main production areas of rice in northeast China in 2018. The pathogenicity and genetic diversity for all these isolates were analyzed by in vitro inoculation and SRAP, respectively. The results showed that there was significant difference on the pathogenicity among isolates in northeast China, among of which 23.3% had strong pathogenicity, 61.9% had medium pathogenicity and 14.8% had weak pathogenicity. There was no significant correlation between geographical origin and pathogenicity. All the 176 isolates of R. solani were divided into six groups by UPGMA cluster analysis with similarity coefficient of 0.63, which showed correlation with geographic location, while not with pathogenicity. Genetic diversity among the 176 isolates was analyzed using SRAP markers. A total of 2 237 amplicons were obtained using 16 pairs of SRAP markers and percentage of polymorphic fragments was 82.16%. The Nei’s gene diversity(h) and Shannon’s information index(I) of all the isolates was 0.2827 and 0.4150, respectively. The genetic distance and geographical distance in the populations of R. solani in different regions of northeast China showed a certain degree of positive correlation. The value of genetic differentiation(Gst=0.3319) and gene flow(Nm=1.0063) indicated high genetic diversity of R. solani and existence of gene exchange. The results of AMOVA indicated that most of the genetic variation existed within populations about 67.84%.