紫丁香天然群体遗传多样性的AFLP分析

 抽取内蒙古大黑山、辽宁北票和山西五老峰3个紫丁香(Syringa oblata Lindl. ) 天然群体为拟似群体, 用筛选出的8对引物, 对群体家系组成的72个样品进行AFLP分析。Nei (1973) 基因多样性指数h = 0.2287, Shannon's信息指数I = 0.3464; 种级遗传多样性Ht = 0.3522, 群体内遗传多样性Hs =0.2287, 群体间遗传多样性Dst = 0.1235, 群体分化系数Gst = 0.3508, 群体间总的基因流的估算值Nm =0.9253, 群体遗传变异的AMOVA分析表明群体的遗传多样性主要分布在群体间, 群体间方差分量的贡献率占51.53%。基于Nei (1972) 遗传距离的UPGMA聚类分析显示群体间的遗传距离与群体的地理距离关系一致。结果表明: 紫丁香群体间的遗传分化较大, 其天然群体缺失造成的现有分布的间断性和地理隔离以及高自交率是导致其群体间的高度分化的主要因素。在目前分布残缺, 群体丢失严重的情况下, 紫丁香种质资源保护和利用策略应为采取优先保存尽可能多的群体。

Genetic Diversity in Natural Populations of Syringa oblata Detected by AFLP Markers

Seeds were collected from 30 trees selected from each of the 3 natural populations of Syringa oblata Lindl. located respectively in Daheishan mountain in Inner Mongolia Autonomous Region, Beipiao in Liaoning Province and Wulaofeng in Shanxi Province. 72 wild accessions of the collections were used in this study. Seedswere germinated and a bulk sample of 20 leaves was collected from each family for molecular marker analysis. Eight EcoRI-MseⅠ AFLP primer combinations revealed 864 legible bands of which 187 were polymorphic markers. Nei's genetic diversitywas 0.2287, Shannon's information index was 0.3464, genetic diversity at species level was 0.3522, observed heterozygosity was 0.2287 within population and 0.1235 among populations, coefficient of genetic differentiation was 0.3508 and the average gene flow estimated from Gst was 0.9253. The results of AMOVA indicated that the variance component of among populations contributes 51.53% to the total genetic variance. UPGMA cluster analysis based on Nei's genetic disitance indicated that genetic distances were closely related to corresponding geographic distances among populations. The results also indicated that genetic differentiation among populations was large, mainly attributable to geographic isolation due to the discontinuous distribution of the species and high rate of selfing. Conservation strategy for the species should be therefore emphasized on conserving as many as possible the existing populationsconsidering the current conditions of severe population fragmentation and losses.