海南南繁区水稻纹枯病菌的遗传多样性与致病力分化

Genetic Diversity and Pathogenicity Differentiation of Rhizoctonia solani AG-1 IA from South China Crop Breeding Area in Hainan Province

【目的】为明确南繁区水稻纹枯病菌(RhizoctoniasolaniAG-1IA)的遗传分化及遗传多样性与致病力的关系,【方法】采用AFLP分子标记技术和离体叶片接种法对南繁核心区(三亚、乐东、陵水)和非核心区(琼中、屯昌和定安)共60株水稻纹枯病菌的遗传多样性、遗传结构和致病力分化进行了测定,并分析了遗传多样性与致病力之间的关系。【结果】聚类分析结果表明,核心区菌株的遗传多样性相对更高;群体遗传结构分析表明,核心区群体的多态性位点百分率(PPL)、Nei基因多样性指数(H)、Shannon信息指数(I)和基因流(N_m)分别为82.24%、0.1932、0.3062和2.5627,高于非核心区群体的67.49%、0.1535、0.2447和0.9365;而核心区群体的基因分化系数(G_(st))为0.1633,低于非核心区群体的0.3481。【结论】核心区菌株的遗传变异程度比非核心区菌株高;核心区不同群体间存在较多的基因交流,而非核心区菌体间的基因交流较少,但遗传变异均主要来自于群体内;总体而言,核心区菌株的遗传分化程度更高。菌株的致病力及其与菌株遗传多样性的相关性分析表明,核心区菌株以中等致病型为主,而非核心区菌株则以中、强致病型为主,但与菌株的AFLP谱系之间的相关均未达显著水平。

【Objective】In order to clarify the genetic differentiation and the correlation between genetic diversity and pathogenicity of Rhizoctonia solani AG-1 ⅠA in South China Crop Breeding Area, the genetic diversity, population genetic structure, pathogenicity and the correlation between genetic diversity and pathogenicity of 60 R. solani AG-1 IA isolates collected from the core region (Sanya, Ledong and Lingshui) and non-core region (Qiongzhong, Tunchang and Ding’an) of South China Crop Breeding Area were comparatively analyzed 【Method】by using AFLP molecular marker technique and detached leaf inoculation method.【Result】The cluster analysis results showed that the genetic diversity of R. solani AG-1 ⅠA in the core region was relatively higher. The analysis results of population genetic structure showed that the percentage of polymorphic loci (PPL), Nei’s gene diversity index (H), Shannon’s information index (I) and gene flow (Nm) in the core population were 82.24%, 0.1932, 0.3062 and 2.5627, respectively, higher than those of non-core population with PPL, H, I and Nm being 67.49%, 0.1535, 0.2447 and 0.9365, respectively. However, the genetic differentiation coefficient (Gst) in the core population was 0.1633, lower than that of non-core population whose Gst was 0.3481.【Conclusion】These results showed that the degree of genetic variation of the isolates from core region was higher than that of the isolates from non-core region. Much gene flow among the core populations and little gene flow among the non-core populations existed, but the genetic variation of both regions was mainly within the population. Overall, the degree of genetic differentiation in the isolates of core region was higher. The results of pathogenicity and correlation between genetic diversity and pathogenicity showed that most isolates from core region belonged to the medium pathotypes and most isolates from non-core region belonged to the medium or strong pathotypes, but there was no correlation between pathogenicity and AFLP lineage.