海南岛油茶种质资源遗传多样性的SRAP分析

为了解海南岛油茶(Camellia oleifera)种质资源的遗传多样性,采用SRAP分子标记,对海南岛油茶主要分布区的31个居群进行了遗传多样性和亲缘关系分析。结果表明,海南岛油茶资源的遗传多样性低,物种水平的多态性百分率(PPB)为98.30%,Nei’s基因多样性(H)为0.222 8,Shannon信息指数(I)为0.353 8;居群水平的PPB=40.96%,观测等位基因数(Na)为1.409 6,有效等位基因数(Ne)为1.237 1, H=0.138 5, I=0.208 3,这与海南岛油茶丰富的表型多样性水平不一致。海南岛油茶资源遗传分化较大,居群间基因交流有限,不同居群间的遗传分化指数(Gst)为0.380,基因流(Nm)为0.813 91。遗传变异主要发生在居群内,有38.05%的变异存在居群间,61.95%存在于居群内。遗传距离为0.022 6～0.276 4,平均为0.107 7,居群间的亲缘关系较近。UPGMA聚类分析表明,在遗传距离为0.11处,可将31个油茶居群聚为6类,表现出明显的行政区域性,而与地理距离关系不大。因此,海南岛油茶资源遗传多样性低,亲缘关系近可能导致自交或近交不亲和,可能是海南油茶林分花量大而结实低的主要内在原因。

Genetic Diversity Analysis of Camellia oleifera Resources Based on SRAP Markers in Hainan Island

In order to evaluate genetic diversity of Camellia oleifera resources in Hainan Island, the genetic diversity and relationship among 31 populations were analyzed by using SRAP molecular marker. The results showed that the genetic diversity of C. oleifera resources in Hainan Island was low, the percentage of polymorphic bands (PPB), Nei''s genetic diversity index (H) and Shannon''s information index (I) were 98.30%, 0.222 8 and 0.353 8 at the species level, and 40.96%, 0.138 5 and 0.208 3 at the population level, respectively, which was inconsistent with their rich phenotypic diversity in Hainan. The coefficient of genetic differentiation among populations (G_st) was 0.380 5, and the gene flow (N_m) was 0.813 9 between different populations, indicating that genetic differentiation was high with limited gene flow among populations. The genetic variation mainly existed within populations (61.95%) and few among them (38.05%). The genetic distance ranged from 0.022 6 to 0.276 4, with the mean of 0.107 7 between 31 populations, which revealed the relatively close genetic relationship among the populations. UPGMA cluster analysis showed that 31 populations could be divided into 6 groups at the genetic distance of 0.11, showing obvious administrative area, but had little to do with geographical distance. So, it was suggested that the relatively close genetic relationship of C. oleifera resources in Hainan Island might cause self-incompatibility, which could be the main internal cause for blooming but low yield of C. oleifera forests in Hainan Island.