不同时期广西马尾松优良种源的遗传多样性变化趋势

马尾松是我国南方重要的乡土树种,近30年来,受人为干扰和破坏十分严重。为了解目前广西马尾松天然遗传资源现状,评价当前种质资源收集对遗传多样性保护的有效程度,采用SSR标记对3个时期收集的广西马尾松3个优良种源进行遗传多样性研究。结果表明:现阶段,马尾松桐棉种源群体的Shannon 多样性指数(I)为 0.64,观测杂合度(H_o)为 0.35,期望杂合度(H_e)为 0.36; 古蓬种源群体Shannon 多样性指数(I)为 0.53,H_o为 0.36, H_e为 0.32。说明广西马尾松遗传多样性仍处于较高水平。将3个种源的遗传多样性进行对比,发现桐棉种源的遗传多样性最高,古蓬种源次之,云开大山种源相对较低。群体间遗传分化系数(G_ST)为0.04,Wright固定指数(F_ST)平均值为0.026,基因流(N_m)大小为9.56,说明3个种源间不存在明显的遗传分化,群体间基因交流顺畅。将不同时期的遗传多样性进行对比分析可知:桐棉种源在18 a内 Shannon 多样性指数(I)下降了5%、期望杂合度(H_e)下降了10%; 古蓬种源Shannon 多样性指数下降了13%、期望杂合度(H_e)下降了14%。说明随着时间的推移,马尾松天然资源受到人为干扰愈来愈强烈,遗传多样性正逐步丧失,急需开展有针对性的保护。

A study on changes of genetic diversity for nearly 50 years in superior provenances of Pinus massoniana in Guangxi

In view of the situation of constant human disturbance to the natural resources of Guangxi Pinus massoniana(masson pine), the dynamic changes of the genetic diversity in provenances of masson pine were studied to provide important reference for the protection of the natural germplasm resources of masson pine. Sixteen SSR molecular markers were used to analyze the genetic diversity of eight populations in three provenances from Guangxi Tongmian, Gupeng and Yunkai Mountain which were collected in 1950s, 1980s and 2012. At the present stage, the mean number of Shannon's information index(I), observed heterozygosity(H_o)and expected heterozygosity(H_e)in Tongmian provenance were 0.64, 0.35 and 0.36 respectively, while Gupeng provenance were 0.53, 0.36 and 0.32 respectively. Compared the genetic diversity level of the 3 provenances, Tongmian provenance possessed the highest genetic diversity, Gupeng followed, Yunkai mountain was relatively low. Coefficient of genetic differentiation among populations(G_ST)was 0.04, average F_ST was 0.026, gene flow(N_m)was 9.56. The results showed that no significant genetic differentiation was available among three provenances, and gene flow among them was smooth. Through the comparing and analyzing of genetic diversity of different periods, the Shannon's information index(I)and expected heterozygosity(H_e)of Tongmian provenance decreased by 5% and 10% within 18 years, and Gupeng provenance dropped 13% and 14%. Which indicated that over the time masson pine natural resources were affected by human interference more and more, genetic diversity is gradually losing, we urgently need to carry out targeted protection.