基于微卫星群体遗传学的栽培枸杞遗传多样性和遗传结构评价

Genetic diversity and genetic structure evaluation of cultivated Chinese wolfberry (Lycium barbarum) based on microsatellite population genetics

该研究利用7对SSR引物,应用GenALEx 6.5,NTSYS,STRUCTURE等软件分析17个栽培宁夏枸杞居群178个个体的遗传多样性和遗传结构,旨在阐明栽培对宁夏枸杞遗传多样性和遗传结构的影响,并提出枸杞种质资源遗传管理及可持续利用的策略。结果显示栽培宁夏枸杞遗传多样性较低,其平均等位基因数N_A、期望杂合度H_E、观察杂合度H_O、Shannon′s信息指数H′分别为3.9,0.4437,0.5566,0.7881。STRUCTURE,UPGMA聚类及PCA分析均表明宁夏枸杞品种间基本没有遗传分化,品种内存在明显的种质混杂。Mantel Test检测显示遗传距离与地理距离不相关。AMOVA分析揭示遗传变异主要发生在居群内个体间(84.58%,P<0.001),几乎没有遗传变异发生在居群间(11.79%,P<0.001)和品种间(3.63%,P<0.001)。栽培已经引起枸杞遗传多样性的明显下降,可能引起近交衰退,应从野生资源寻找新的种质资源,以改良现有栽培枸杞的种质。另一方面,栽培宁夏枸杞品种间、居群间存在明显的均质化和种质混杂,需要品种提纯且要避免混杂种质流入其他野生居群,污染其他野生枸杞种质。

A total of 178 Chinese wolfberry individuals from 17 populations were detected by 7 pairs of SSR primers to evaluate genetic diversity and structure,using software GenALEx 6.5,NTSYS,STRUCTURE,the effects of cultivation on genetic diversity and structure were clarified aiming to find the strategies for genetic management and sustainable use.The results showed that the genetic diversity of cultivated Chinese wolfberry was low.The average number of alleles N_A,expected heterozygosity H_E,observed heterozygosity H_O,and Shannon′s information index H′was 3.9,0.4437,0.5566,0.7881,respectively.STRUCTURE,UPGMA clustering and PCA test indicated that Chinese wolfberry varieties were severely intermixed but no differentiation among varieties.Mantel test showed no significant correlation between genetic distance and geographic distance.AMOVA analysis showed that genetic variation mainly occurred among individuals within the population(84.58%,P<0.001),and there was almost no genetic differentiation between varieties(3.63%,P<0.001)and between populations(11.79%,P<0.001).The cultivation has caused a significant decline in the genetic diversity of Chinese wolfberry,which may cause inbreeding decline.New germplasm resources should be sought from the wild to improve the existing cultivars.On the other hand,there are obvious homogenization and germplasm intermixing between cultivated varieties and populations.Meanwhile,Chinese wolfberry cultivars should be purified and prevented from flowing into the wild population,in case of causing pollution of the wild germplasm.