都支杜鹃遗传多样性的ISSR分析

通过ISSR分子标记对都支杜鹃(Rhododendron shanii)5个居群114个个体的遗传多样性进行了分析。8个引物共检测到69个位点，其中多态位点36个，多态位点百分率 （P） 为52.17%；物种水平的Shannon多样性指数（I）为0.2536，Nei指数（H）为0.1659；居群水平的P、I和H分别平均为32.46%、0.1955和0.1344；Nei’s基因分化系数GST=0.1845，基因流Nm=2.2104；遗传结构的AMOVA分析显示，总的遗传变异中88.3%存在于居群内，11.7%存在于居群间；PCA分析和Splite Tree构建的NJ树均显示居群间分化小；遗传距离与地理距离显著相关。较强的基因流、多年生木本及异交与分布区狭窄等可能是导致都支杜鹃遗传多样性较低的主要原因。目前该种的保护应以就地保护为主，尤其要注意对大居群的保护。

Genetic Diversity of Rhododendron shanii Based on ISSR Analysis

 Genetic diversity across five sampled populations of Rhododendron shanii Fang was analyzed using ISSR molecular markers. A total of 69 loci, 36 of which were polymorphic, were detected using 8 ISSR primers. At the species level, total percentage of polymorphic loci (P) was 52.17%, and Shannon’s information index (I) and Nei’s gene diversity (h) were 0.2536 and 0.1659, respectively. At the population level, the mean value of P, I and h were 32.46%, 0.1955 and 0.1344, respectively. The coefficient of genetic differentiation (GST) was 0.1845 and the gene flow (Nm) was 2.2104. Analysis of molecular variance (AMOVA) demonstrated that the within populations component accounted for 88.3% of the total variation, while the among populations component accounted for 11.7%. The results of principal component analysis (PCA) and Neighbor joining also revealed that differences among populations were small and most genetic diversity was present within populations. Mantel’s test showed there was significant correlation between genetic and geographical distance. The pattern of genetic structure recorded in R.shanii possibly stems from fairly frequent gene flow among populations, a perennial woody habit and a limited distribution range. At present, priority must be given to in situ conservation of extant populations. In this regard, attention should be paid to large populations of R.shanii, which appear to contain most of the genetic diversity present within the species.