四川花萼山巴山榧树不同世代种群的遗传多样性

Genetic Diversity of Different Generations of Torreya fargesii Population in Hua'e Mountain, Sichuan Province

为揭示巴山榧树遗传多样性在时间尺度上的变化规律,根据胸径大小将四川省花萼山国家级自然保护区巴山榧树群体划分为幼苗、小树和成树3个世代,利用ISSR分子标记技术对3个世代共70个个体的遗传多样性及遗传分化进行了分析。10条ISSR引物扩增共检测到125个多态位点,多态位点百分率为74.85%,表明花萼山巴山榧树群体具有较高的遗传多样性。ISSR分析显示3个世代的多态位点百分率、Shannon's信息指数(I)和Nei's基因多样性指数(H)均以成树最高,幼苗最低,幼苗的遗传多样性指数低于小树和成树,表明花萼山巴山榧树种群世代间的遗传多样性呈下降趋势。巴山榧树3个世代间的基因分化系数Gst=0.109 8,基因流Nm=4.053 7。3个世代间的遗传一致度以幼苗与小树间最大,遗传距离则以幼苗与小树间最小。上述研究结果为深入研究巴山榧树遗传资源和制定有效的保护措施提供了科学依据。

In order to reve al the change rule of genetic diversity of Torreya fargesii on the time scale, the population of T. fargesii collected from Hua’e Mountain National Nature Reserve in Sichuan Province was divided into 3 generations according to the diameter at breast height, i.e. seedlings, saplings, adult trees. The genetic diversity and genetic differentiation among 3 generations(70 samples) were analyzed by Inter-simple sequence repeat(ISSR) molecular marking technique. A total of 125 polymorphic loci were detected by 10 ISSR primers, and the percentage of polymorphic loci was 74.85%, indicating that the genetic diversity of T. fargesii population was quite high. ISSR analysis showed that the highest percentage of polymorphic loci, the Shannon’s information index(I) and the Nei’s genetic diversity index(H) were detected in adult trees, and the lowest were detected in seedlings.The genetic diversity index of the seedlings was lower than that of the saplings and adult trees, indicating that the genetic diversity of the generations of T. fargesii population in Hua’e mountain was in decline. The gene differentiation coefficient(Gst) among 3 generations of T. fargesii population was 0.109 8 while the gene flow(Nm) was 4.053 7.The genetic identity between saplings and seedlings was the highest, and the genetic distance between saplings and seedlings was the lowest among 3 generations. The experimental results would provide a scientific basis for the further research and effective protection of the genetic resource of T. fargesii.