高黎贡山自然保护区长蕊木兰遗传多样性的ISSR分析

ISSR analysis of genetic diversity of rare and endangered species Alcimandra cathcartii in the Gaoligong Mountains National Nature Reserve

长蕊木兰是具有重要分类和观赏价值的国家一级保护植物。采用ISSR分子标记技术,对云南省高黎贡山自然保护区长蕊木兰3个居群62株个体的遗传多样性进行了研究。结果表明:15个引物共检测到187个有效位点,其中多样性位点171条,在物种水平上多态位点百分率(PPB)为91.44%,居群水平上整顶(ZD)居群PPB最高(66.30%),大蒿坪(DHP)居群PPB最低(21.93%);居群间的基因分化系数(Gst=0.2294)、Shannon居群分化系数(0.27)和分子遗传变异分析(AMOVA)的变异百分率(居群间的变异百分率为27%,居群内的变异百分率为73%)均表明,长蕊木兰遗传变异主要存在于居群内部;聚类结果显示,最大的一类中涵盖了3个居群的绝大多数个体;Mantel检测遗传距离与地理距离之间不存在明显相关性(r=-0.519,P=0.323)。这些结果表明,长蕊木兰具有较大的遗传多样性,但居群间有较大的遗传分化。文章分析了长蕊木兰的濒危原因并提出保护策略,即通过加强已建自然保护区的管理,实施就地保护是最佳选择。

Alcimandra cathcartii is a rare and endangered plant species, with important value in taxonomy and ornamental horticulture, and it is also a firstclass nationally protected species in China. Analysis of ISSR markers was conducted on three natural populations （NK, ZD and DHP） of A. cathcartii from Gaoligong Mountains National Nature Reserve with the objective of investigating the genetic diversity within and among the populations. Leaf samples of 62 individuals from the three populations were collected for DNA extraction. The results were as follows： （1） Fifteen ISSR primers were used to generate highly reproducible and stable DNA fragments （the sizes of ISSRPCR products ranged from 250 to 2200 bp）. One hundred and eighty seven discernible DNA fragments were produced, among which 171 fragments were polymorphic loci （mean 12.5 bands and 11.3 polymorphic bands per primer）. The percentage of polymorphic bands （PPB） was 91.44% at the species level, and PPB within population ranged from 21.93% （DHP population） to 66.30% （ZD population）. （2） The genetic differentiation among populations was detected in A. cathcartii ／[0.2294, 0.27 and 27% for Nei’s genetic coefficient of differentiation （Gst）, Shannon’s diversity index and AMOVA／], which indicated that genetic differentiation mainly occurred within populations. The cluster analysis showed that the largest category included most individuals of the three populations. （3） The correlation coefficient （r=-0.519, P=0.323） obtained by Mantel test did not show any significant relationship between the matrices of geographical distances and pairwise genetic distances based on ISSR. On the basis of the genetic and ecological information, it is recommended that strengthening the nature reserve management and promoting the insitu conservation is a promising strategy for the protection of this species.