大花无柱兰遗传多样性的SRAP标记分析

大花无柱兰是一种珍稀兰科植物，具有一定的观赏和药用价值，但数量十分稀少，该物种亟待保护。本研究采用SRAP分子标记技术，对10个居群的115份DNA样品进行PCR扩增，并开展遗传多样性分析。从81对引物中筛选出9个条带清晰、多态性好、重复性高的引物组合，共扩增得到305条谱带。在物种水平上，多态性比率（PPB）为100%，Nei’s基因多样性指数（H）为0.209 8，Shannon’s指数（I）为0.340 2；在居群水平上，PPB为24.59%～52.13%，H为0.079 6～0.165 5，I为0.120 9～0.252 3。居群水平上，基因分化度（Gst）为0.520 9，基因流（Nm）为0.459 9，遗传距离为0.091 9～0.198 4。UPGMA聚类结果表明，10个居群可分为3大类，地理距离相近的居群优先聚集。大花无柱兰的遗传多样性较为丰富，居群间存在一定的遗传分化和基因交流，可采用就地保护和人工栽培等方式加以保护。

Assessment of genetic diversity inAmitostigma pinguiculum revealed with SRAP Markers

Amitostigma pinguiculum is a rare Orchidaceae plant with both medicinal and ornamental values. However, the number of individuals is very low so, this species should be protected as soon as possible. This study applied SRAP technique to amplify 115 DNA samples from tenpopulations to analyze its genetic diversity . Nine primer combinations which had higher reproducibility, resolution, and polymorphism were screened from 81 primer pairs, and 305 DNA fragments were generated. At the species level, the percentage of polymorphic bands (PPB) is 100%, and the Nei’s genetic diversity (H) and Shannon’s information index (I) are 0.209 8 and 0.340 2, respectively; while at the population level, PPB, H, and I range from 24.59% to 52.13%, 0.079 6 to 0.165 5, and 0.120 9 to 0.252 3, respectively. The coefficient of genetic differentiation (G_st) of populations and the gene flow (N_m) is 0.520 9 and 0.459 9, respectively, and the genetic distance range from 0.091 9 to 0.198 4. The UPGMA cluster results indicated that the ten populations were divided into three categories, and the populations from nearby areas were preferentially grouped. The genetic diversity of A. pinguiculum is abundant, and there exists some genetic differentiation as well as gene flow among populations. The species can be protected by in situ conservation and artificial cultivation.