江西主要山脉春兰野生居群遗传结构与分化

利用ISSR分子标记对江西省主要山脉的21个春兰(Cymbidium goeringii(Rchb.f.)Rchb.f.)居群进行居群遗传结构研究。结果显示,利用14个筛选的引物共扩增出139条条带,其中多态性条带118条,多态性条带百分率(PPL)为84.89%。21个居群的Nei s基因多样性(He)为0.2292,Shannon指数(I)为0.3613。AMOVA分析表明,春兰居群间变异占50.79%,居群内变异占49.21%,居群间的遗传分化大于居群内的分化。STRUCTURE群体遗传结构和UPGMA聚类分析均表明,江西主要山脉的春兰居群存在地理隔离和生境片断化。推测江西春兰曾广泛分布于罗霄山脉和武夷山脉,受第四纪冰期影响,春兰群体因气候剧烈变化而骤减,仅在山脉间适宜的环境中得以保存并繁衍至今,罗霄山脉和武夷山脉是春兰最主要的两个冰期避难所。综合遗传多样性与居群遗传结构特点,建议在遗传多样性较高的石城(SC)、宜丰(YF)、贵溪(GX)居群设点进行就地保护;对资源破坏严重的大余(DY)和井冈山(JGS)居群实行迁地保护。

Genetic structure and differentiation of wild populations of Cymbidium goeringii (Rchb. f.) Rchb. f. in the main mountain range of Jiangxi Province,China

We used ISSR molecular markers to study the genetic structure of 21 Cymbidium goeringii (Rchb. f.) Rchb. f. populations in the main mountain range of Jiangxi Province, China. Results showed that 139 bands were amplified by the 14 selected primers. Among these bands, 118 were polymorphic, resulting in a percentage of polymorphic bands (PPL) of 84.89%. The Nei’s gene diversity (He) and Shannon index (I) values of the 21 populations were 0.2292 and 0.3613, respectively. AMOVA analysis unveiled that inter-population variation (50.79%) was greater than intra-population variation (49.21%). Both these results of population genetic structure and UPGMA cluster analysis showed that the C. goeringii populations in the main mountain range of Jiangxi Province were geographically isolated and their habitats were fragmented. Based on the above analysis, we inferred that C. goeringii was once widely distributed in the mountain ranges of Luoxiao and Wuyi. Following the Quaternary glacial period, these populations declined sharply due to severe climate change, but were preserved to the present day in suitable environments between these two mountains. Thus, the Luoxiao and Wuyi mountains formed primary ice-age refuges for C. goeringii. These results, combined with the genetic diversity and structure of C. goeringii populations, may provide a valuable basis for conservation strategies. In situ conservation would be suitable for the Shicheng (SC), Yifeng (YF), and Guixi (GX) populations due to their sufficient genetic diversity, whereas ex situ strategies should be considered for Dayu (DY) and Jinggangshan (JGS), which have experienced serious resource destruction.