广西部分地区野生茶树遗传关系EST-SSR标记分析

Genetic relationship analysis of wild tea tree germplasm resources in part of Guangxi based on EST-SSR markers

关键词:  野生茶树, 种质资源, EST-SSR, 遗传多样性, DNA分子指纹图谱, 广西

Key words:  wild tea tree, germplasm resources, EST-SSR, genetic diversity, DNA molecular fingerprint, Guangxi

摘要:

为了明确广西野生茶树种质资源的遗传背景,该研究从广西的宁明县、金秀县、苍梧县收集到14份地方野生茶树种质资源,以17个国家级茶树良种作为参照,采用EST-SSR分子标记技术,探讨了广西这三个地方野生茶树与国家级茶树良种间的亲缘关系以及广西地方茶树自身的遗传多样性。结果表明:15对EST-SSR引物共检测到68个等位基因,平均每个引物可扩增出4.53个,其中多态性位点为60个,多态性比率达88.2%。平均观测杂合度、平均期望杂合度、平均Shannon信息指数分别为0.42、0.55和0.97。PIC值在0.23～0.74之间,平均为0.52,多态性较好。遗传相似系数在0.53～0.9之间,平均值为0.71,31份供试材料在遗传相似系数为0.71分为5组群,76%参照品种聚在A组群,而广西本地的野生茶树资源则主要分布在B、C、D、E组群。利用该研究中的4对核心引物即可将31份供试材料全部区分开,挑选其中10个多态性较好的等位位点进行编码,构建31份供试种质的DNA分子指纹图谱。这表明广西野生茶树资源与国家级茶树良种间遗传差异较大、亲缘关系较远、遗传基础宽、多样性非常丰富,可作为茶树育种的亲本或开展茶树功能基因研究的材料。

Abstract:

In order to clarify the genetic background of wild tea tree germplasm resources in Guangxi, fourteen local wild tea tree germplasm resources were collected from Ningming County, Jinxiu County and Cangwu County, Guangxi. Taking seventeen state-level tea cultivars as reference, and adopting EST-SSR molecular marker technology, the research focused on the genetic relationship between these wild tea trees and the state-level tea cultivars in three places of Guangxi and the genetic diversity of local tea trees in Guangxi. The experiment results showed that a total of 68 alleles were detected in fifteen pairs of SSR primers, and each primer could amplify 4.53 by average, of which polymorphic site were 60, and the polymorphic ratio was 88.2%. The average observed heterozygosity, average expected heterozygosity, and average Shannon information index were 0.42, 0.55, and 0.97 respectively. The PIC value was between 0.23-0.74 with an average of 0.52, and the polymorphism was good. The genetic similarity coefficient was between 0.53 and 0.9, with an average value of 0.71. The test materials were divided into five groups at genetic similarity coefficient of 0.71, among which 76% reference warietics were clustered in Group A, while the local wild tea tree resources in Guangxi were mainly distributed in B, C, D and E groups. By using the four pairs of core primers in this study, 31 test materials could be completely distinguished. Ten allelic sites with good polymorphisms were selected for coding, and 31 DNA fingerprints of the tested germplasm were constructed. The study indicates that there is a great genetic difference between the wild tea trees in Guangxi and the state-level tea cultivars. The wild tea tree resources in Guangxi has distant genetic relationship, wide genetic basis and rich diversity, and can be used as the parent for tea tree breeding or materials for studying tea tree functional genes.