中华水韭遗传多样性的RAPD分析

采用RAPD方法对珍稀濒危植物中华水韭(Isoetes sinensis)4个自然居群的48个样品进行了DNA多态性分析。从60个随机引物中筛选出14个有效引物，共产生124条DNA片段，其中72条为多态性条带，总的多态位点百分率(PPB)为58．06％。各居群间多态位点百分率差异显著(0．81％-12．90％)。AMOVA分析结果表明，4个居群间基因分化系数Фst=0．5894，即遗传变异中有相当一部分来源于群体间(58．94％)。日益缩小的种群规模而导致的居群内近交和遗传漂变的发生以及居群间有限的基因交流可能是中华水韭目前遗传结构的主要成因。鉴于目前中华水韭居群内个体数偏少、遗传多样性较低的现状，建议对其进行就地保护并保护尽可能多的生境，对不同自然居群内的个体进行植株相互移栽和育苗移栽，以提高不同居群间的基因交流，尽可能地保护中华水韭的遗传多样性。

RAPD analysis for genetic diversity of Isoetes sinensis

Random Amplified Polymorphic DNA (RAPD) markers were used to measure genetic diversity of 48 individuals from four natural populations of Isoetes sinensis, a rare and endangered plant in China. A total of 124 DNA fragments were scored from 14 RAPD primers, of which 58.06% were polymorphic.A low level of genetic diversity within populations was detected, with PPB (percentage of polymorphic bands) values ranging from 0.81% to 12.90%. An Analysis of Molecular Variance (AMOVA) was used to apportion the variation within and among populations. Results indicated that most of the variation (58.9%) resided among populations and a small amount of variation (41.1%) represented differences within populations. Inbreeding is likely the factor that results in the low level of genetic diversity within the populations. Genetic drift and limited gene flow might also have enhanced genetic differentiation among the populations. In view of the ecological and genetic information available for I. sinensis, we sug- gest establishing as many in situ conservation spots as possible and cross transplanting plants or seedlings mutually among populations in order to enhance gene flow. By this means, the genetic diversity resources of I. sinensis can be preserved to the greatest extent.