Comparative analysis of genetic structure and differentiation of guangdong and guangxi tea germplasms based on est-ssr markers | 基于EST-SSR的广东与广西茶树资源遗传结构和遗传分化比较分析

chinois. 目的通过揭示茶树资源遗传多样性、遗传结构和遗传分化关系，为资源的有效保护和充分利用提供理论依据。方法利用109对核心EST-SSR标记对广东、广西的105份茶树核心资源进行遗传多样性和遗传分化比较分析；同时对广东和广西资源组群间、组群内白毛茶和茶种群间、种群内进行AMOVA分子方差分析，进一步剖析遗传结构，并绘制群体遗传结构图。结果109对核心EST-SSR标记共检测到435个等位基因，平均等位基因（NA）3.99个，平均有效等位基因（NE）为2.12，平均Nei's基因多样性（H）为0.59，平均观测杂合度（Ho）为0.32，平均期望杂合度（He）为0.46，平均多态性信息含量（PIC）为0.56。广东茶树资源遗传多样性的上述6个参数均小于广西茶树资源。广东白毛茶NA和H低于广东茶，NE、He、Ho和PIC与茶较为接近；广西白毛茶NA大于广西茶，但是NE、He和H低于茶。F-统计量分析表明白毛茶与茶种群内近交系数（Fis）、种群间近交系数（Fit）和种群遗传分化（Fst）都较低，基因流（Nm）都较高。广东白毛茶与广西白毛茶Fst为0.04，基因交流相对较低为6.26。AMOVA分析显示组群间遗传变异为3.09%，组群内种群间遗传变异为2.22%，种群内遗传变异为94.69%。群体遗传结构显示105份茶树资源可分为3个类群，类群Ⅰ由6份选育品种组成；类群Ⅱ由43份广东资源和16份广西资源组成；类群Ⅲ包括广西36份和广东4份资源。结论广东茶树资源遗传多样性程度低于广西。广东白毛茶遗传多样性比广东茶丰富，种群遗传分化低，存在较频繁的基因交流。广东白毛茶遗传多样性低于广西白毛茶，遗传分化相对较高，基因流较低。AMOVA分析显示遗传变异主要分布于广东、广西茶树资源群体内。

anglais. Objective The well understanding of genetic diversity, structure and differentiation of tea germplasms is important for their effective conservation and reasonable utilization. Method One hundred and nine core EST-SSR markers were selected and used to analyze the genetic diversity and differentiation of 105 tea accessions from Guangdong and Guangxi provinces. Molecular variance (AMOVA) analysis of inter-groups, inter-populations and individuals within populations was conducted, and then the model-based genetic structure was constructed. Result A total of 435 alleles were identified with an average of 3.99 alleles per marker (NA). The average of effective number of alleles (NE), Nei's gene diversity (H), observed heterozygosity (Ho), expected heterozygosity (He) and polymorphism information content (PIC) was 2.12, 0.32, 0.59, 0.46 and 0.56, respectively. Guangdong tea germplasms showed lower values of the six indexes mentioned above, compared to Guangxitea. Guangdong Baimaocha (Camellia sinensis var. pubilimba Chang) had lower NA and H values and similar NE, He, Ho and PIC values compared with Guangdong tea (C. sinensis (L.) O. Kuntze). While Guangxi Baimaocha had higher NA value, lower NE, He and H values than Guangxi tea. The values of Fis, Fit and Fst were low among Guangxi and Guangdong Baimaocha and tea populations with strong gene flow. The same results were found between Baimaocha and tea. There were weak genetic differentiation (0.04) and gene flow (6.26) within Baimaocha population. Molecular variance (AMOVA) analysis showed that there was a relatively low level (3.09％) of genetic variation among Guangdong and Guangxi tea germplasms, that within the populations was 94.69%. The population structure analysis could divide all the 105 accessions into 3 groups. Six developed cultivars were grouped into groupⅠ; group Ⅱ consisted of 43 accessions from Guangdong and 16 from Guangxi. The remaining 36 accessions from Guangxi and 4 from Guangdong were assigned into group III.ConclusionThe genetic diversity of Guangdong tea germplasms was lower than that of Guangxi. Genetic differentiation was insignificant between populations with strong gene flow. Guangdong Baimaocha had much more abundant genetic diversity than Guangdong tea, and genetic differentiation was weak with frequent genetic exchange. Guangxi Baimaocha showed richer genetic diversity than Guangdong Baimaocha, with relatively high genetic divergence and weak gene flow. AMOVA showed that the variation level within Guangdong and Guangxi populations was absolutely higher than among populations.