广西普通油茶种质资源遗传多样性的SSR分析

Genetic diversity analysis of Camellia oleifera in Guangxi using SSR markers

关键词:  普通油茶, SSR标记, 遗传多样性, 遗传结构, 复等位基因

Key words:  oil tea(Camellia oleifera), SSR marker, genetic diversity, genetic structure, multiple alleles

摘要:

普通油茶(Camellia oleifera)是我国分布最广、产量最多的山茶属中一个重要油料树种。广西是普通油茶的重要分布区,种质资源十分丰富。为深入了解广西普通油茶种质资源的遗传变异,服务于种质保存和品种选育,该研究首先对已开发的SSR分子标记进行多态性筛选和评价,在此基础上利用多态性较高的引物,对97份广西有代表性的普通油茶种质资源进行遗传多样性分析。结果表明:(1)在已开发的10对油茶SSR分子标记中,7对能稳定扩增且表现为共显性,2对扩增不稳定,另外1对无法扩增出产物。(2)7对共显性SSR标记总共检测到33个等位基因,每对标记检测到等位基因数目的变化范围为3～6个,平均每个位点等位基因数为4.714 3个,有效等位基因数目的变化范围为2.084 2～4.314 8,平均有效等位基因数为2.828 8; 基因多样性变化范围为0.520 2～0.768 2,平均每个位点基因多样性为0.628 1。(3)参试群体中绝大多数位点未处于Hardy-Weinberg平衡,存在遗传结构; 观测杂合度和期望杂合度的变化范围分别为0.413 0～0.670 1和0.523 3～0.772 4,其平均值分别为0.569 8和0.631 6。(4)种质资源间遗传距离变化范围为0.05～0.791 7,平均遗传距离为0.354 5; UPGMA聚类显示相同来源的种质资源无法聚成一类,在同一聚类分支上混有不同来源的种质资源。这表明已开发的油茶SSR分子标记适用于广西普通油茶,广西普通油茶种质资源拥有较丰富的遗传多样性。该研究结果为广西普通油茶资源的深度开发和高效利用提供了科学依据。

Abstract:

Oil tea(Camellia oleifera)is the important oiltree in our country with the vastest area of distribution and the most products in the genus of Camellia. Guangxi Zhuang Autonomous Region, the important distribution area of oil tea, abounds in oil tea germplasm resources. In order to evaluate genetic variation of germplasm resources of oil tea in Guangxi for germplasm conservation and cultivar selection, 10 SSR primer pairs were screened and evaluated in the present study, then genetic diversity of 97 representive germplasm resources of oil tea in Guangxi was analysed based on the polymorphic SSR markers. The findings indicated as follows: Firstly, of the ten developed SSR primer pairs, seven codominant primer pairs could produced stable amplicons, and another two primers could produce unstable amplicons; the remaining one yielded no band on the gel. Secondly, a total of 33 alleles were detected among 97 oil tea germplasm resources using seven codominant SSRs, and the number of alleles was from three to six with an average of 4.714 3 for every pair of primers; the number of effective allele ranged from 2.084 2 to 4.314 8 with an average of 2.828 8, and the gene diversity was from 0.520 2 to 0.768 2 with an average of 0.628 1. Thirdly, almost loci out of Hardy-Weinberg equilibrium meant genetic structure in the population, the ranges of observed and expected heterozygosity were 0.413 0-0.670 1 and 0.523 3-0.772 4, with the averages of 0.569 8 and 0.631 6. Finally, the range of genetic distances among germplasm resources was 0.05-0.791 7, with an average of 0.354 5. The cluster analysis based on UPGMA method revealed that the germplasm resources from the same places could not cluster in the same branch, on the other hand, the germplasm resources in one branch came from several places. The foregoing results reveavled that the developed SSRs of oil tea were suitable to work in the oil tea in Guangxi and the genetic diversity of germplasm resources in Guangxi was relatively higher. Those findings provide the scientific evidences for deep exploitation and efficient utilization of genetic resources of oil tea in Guangxi.