望春玉兰种质资源遗传多样性分析与核心种质构建

Genetic Diversity Analysis and Core Collection Construction of Magnolia biondii Germplasm

对河南省南召县917份望春玉兰(Magnolia biondii)种质材料利用细胞流式仪进行基因组倍性分析,并采用SSR标记分析其遗传多样性和遗传结构。此外,采用模拟退火法分别基于遗传多样性最大化(simulated annealing algorithm based on the maximizing genetic diversity,SAGD)和等位基因最大化(simulated annealing algorithm based on maximizing allelic richness,SANA)构建望春玉兰核心种质。结果显示:所检测的望春玉兰种质材料全部为二倍体植株;10对SSR引物共检测到57个等位基因(N_(a)),平均有效等位基因数(N_(e))为2.667,Shannon’s信息指数(I)、观测杂合度(H_(o))、期望杂合度(H_(e))和多态性指数(PIC)分别为1.124、0.422、0.586和0.547,表明望春玉兰种质资源具有丰富的遗传多样性。群体遗传结构和聚类分析均显示,917份望春玉兰种质材料可以分为4个亚群,不同亚群之间存在明显的基因交流和渗透。基于SAGD方法构建核心种质的各遗传参数基本都高于SANA法。利用SAGD方法筛选得到183份望春玉兰核心种质,占原有种质的20%,N_(a)、N_(e)、I、H_(o)和H_(e)的保留率分别为94.74%、105.40%、103.38%、104.27%和104.61%;主坐标分析(principal coordinate analysis,PCoA)表明构建的望春玉兰核心种质在整个原始种质的主坐标图内均匀分布,具有良好的代表性,可以为种质资源收集保存及创新利用提供科学依据。

In this study,genome ploidy levels of 917 Magnolia biondii germplasms collected from Nanzhao Country,Hennan Province were analyzed by using the flow cytometry.Genetic diversity and genetic structure of the Magnolia biondii germplasms were investigated by using SSR markers.In addition,simulated annealing algorithm was used to construct a core collection for the M.biondii Pamp.germplasms based on the maximizing genetic diversity(SAGD)and allele maximization(SANA),respectively.The results showed that all the investigated M.biondii Pamp.germplasms were diploids.A total of 57 alleles(N_(a))were detected by 10 SSR primers,and the average of effective allele number(N_(e))was 2.667.The Shannon’s information index(I),the observed heterozygosity(H_(o)),the expected heterozygosity(H_(e))and the polymorphism information content(PIC)were 1.124,0.422,0.586 and 0.547,respectively,indicating a high genetic diversity in the germplasm resources of M.biondii Pamp.Both genetic structure and cluster analysis analyses indicated that the 917 M.biondii Pamp.germplasms could be divided into four subgroups,and there were obvious genetic exchanges among different subgroups.The genetic parameters of core collection obtained by SAGD were higher than those of SANA,therefore 183(20%of the original collection)germplasms were selected through the SAGD method to construct the core collection of M.biondii Pamp.The retention rate of N_(a),N_(e),I,H_(o)and H_(e)was 94.74%,105.40%,103.38%,104.27%and 104.61%,respectively.The principal coordinate analysis(PCoA)showed that the core collection constructed by this study was uniformly distributed within the initial collection and had a good representation.The constructed core collection will provide a scientific basis for conservation and utilization of M.biondii Pamp.germplasm resources.