基于SSR标记的厚朴亲本及其子代群体的遗传多样性分析

Analysis on genetic diversity of populations of parents and their progenies of Magnolia officinalis based on SSR marker

以来自浙江遂昌的5株厚朴（Magnolia officinalis Rehd.et Wils.）单株为母本,来自浙江磐安和富阳、江西分宜以及湖南沅陵的厚朴群体为父本,获得7个杂交授粉子代群体;并对5株母本单株进行自由授粉,获得5个自由授粉后代群体;在此基础上,采用SSR标记技术对厚朴亲本群体以及杂交和自由授粉子代群体的遗传多样性进行分析。结果表明：13对SSR引物扩增的片段长度为105~297 bp,共检测到54个等位基因,每个位点的观测等位基因数和有效等位基因数分别为4.2和2.6。总体上,杂交授粉子代群体的遗传多样性最高,其Shannon多样性指数（I）、Nei’s基因多样性指数（h）和期望杂合度（He）平均值分别为1.049 3、0.577 3和0.638 2;亲本群体的遗传多样性略低于其杂交授粉子代群体,其I、h和He平均值分别为1.022 1、0.559 7和0.601 3;自由授粉子代群体的遗传多样性最低,其I、h和He平均值分别为0.813 8、0.480 8和0.530 0。7个杂交授粉子代群体亲本间的Nei’s遗传距离为0.576 2~1.181 1,且与杂交授粉子代群体的遗传多样性呈正相关,但相关性不显著（R=0.392 4）。7个杂交授粉子代群体间的Nei’s遗传距离和遗传一致度分别为0.274 9~0.804 6和0.446 4~0.759 6,其中来源于同一父本的杂交授粉子代群体间的遗传一致度最高,且Nei’s遗传距离越大其遗传一致度越小。聚类分析结果表明：在Nei’s遗传距离为0.93处,供试的5个母本单株以及3个父本群体、7个杂交授粉子代群体和5个自由授粉子代群体可分成3类,其中来源于同一父本的杂交授粉子代群体及其父本群体具有较近的亲缘关系。研究结果显示：厚朴杂交授粉子代群体的遗传多样性水平明显高于其自由授粉子代群体,并且总体上高于其亲本,说明杂交授粉可加速厚朴群体间的基因交流,丰富其群体的遗传多样性。

Seven progeny populations of hybrid pollination were obtained by taking five individuals of Magnolia officinalis Rehd. et Wils. collected from Suichang of Zhejiang as female parents, and populations of M. officinalis collected from Pan＇an and Fuyang of Zhejiang, Fenyi of Jiangxi and Yuanling of Hu＇ nan as male parents. And five female parent individuals were free pollinated and five progeny populations of free pollination were obtained. On this basis, genetic diversity of parent populations and progeny populations of hybrid and free pollinations of M. officinalis were analyzed by SSR marker technology. The results show that length of bands amplified by 13 pairs of SSR primer are 105- 297 bp, 54 alleles are detected totally, and observed and effective allele numbers at each locus are 4.2 and 2.6, respectively. highest, averages of its Overall, genetic diversity of progeny population of hybrid pollination is the Shannon diversity index （I） , Nei＇s gene diversity index （h） and expected heterozygosity （He） are 1. 049 3, 0. 577 3 and 0. 638 2, respectively; genetic diversity of parent population is slightly lower than that of progeny population of hybrid pollination, averages of its I, h and He are 1. 022 1, 0. 559 7 and 0. 601 3, respectively ; and genetic diversity of progeny population of free pollination is the lowest, averages of its I, h and He are 0. 813 8, 0. 480 8 and 0. 530 0, respectively. Nei＇ s genetic distance between parents of seven progeny populations of hybrid pollination is 0. 576 2-1. 181 1, and there is positive correlation between Nei＇s genetic distance and genetic diversity of progeny populations of hybrid pollination, but the correlation is not significant （R = 0. 392 4）. Nei＇ s genetic distance and genetic identity among seven progeny populations of hybrid pollination are 0. 274 9- 0. 804 6 and 0. 446 4-0. 759 6, respectively. In which, genetic identity among progeny populations of hybrid pollination from the same male parent is the highest, and the greater the Nei＇ s genetic distance, the smaller the genetic identity. The cluster analysis result shows that at Nei＇ s genetic distance 0.93, five female parent individuals, three male parent populations, seven progeny populations of hybrid pollination and five progeny populations of free pollination tested can be divided into three categories, in which, there is a close relationship between progeny populations of hybrid pollination from the same male parent and their male parent populations. It is suggested that level of genetic diversity of progeny populations of hybrid pollination of M. officinalis is obviously higher than that of progeny populations of free pollination, and is higher generally than that of parents, meaning that hybrid pollination can accelerate gene exchange among populations and rich population genetic diversity of M. officinalis.