云南穗花杉的遗传多样性研究

Genetic Diversity of the Relict Plant Amentotaxus yunnanensis

摘要:

采用随机扩增多态DNA(RAPD)方法对云南穗花杉(Amentotaxus yunnanensis) 4个居群和台湾穗花杉(Amentotaxus formosana) 1个居群共104个个体进行了遗传多样性分析。9个随机引物共扩增出清晰谱带143条。云南穗花杉在物种水平上遗传多样性较高(多态位点百分率P为79.0%, 基因多样性指数He为0.2718), 但云南穗花杉和台湾穗花杉居群内遗传多样性均较低(P为18.0%、6.9%;He为0.0688、0.0198)。云南穗花杉居群间遗传分化强烈(AMO-VA, G_ST 和Shannon 多样性指数分别为0.7611,0.7503和0.7526)。据推测,第四纪冰川引起的瓶颈效应,小规模居群引起的遗传漂变及幼苗成活率低等因素都加剧了居群间的遗传分化。建议对所研究的云南穗花杉全部居群予以保护,特别是对云南西畴和贵州兴义市七舍两个具有相对较高遗传多样性的居群应该优先建立就地保护点,以达到最大限度保存云南穗花杉遗传多样性的目的。

Abstract:

A mentotaxus yunnanensis Li(Taxaceae)is a rare and relict species with limited distribution．RAPD markers were used to determine the genetic variation within and among 4 populations of A.yunnanensis and one population of A. formosana. Although high level ofgenetic diversity was found in A. yunnanensis at the species level(Percentage of polymorphic loci：79.0％，Nei’S genetic diversity：0.2718)，there existed much lower genetic variation within populations(Percentage of polymorphic loci：18.0％ and 6.9％：Nei’s genetic diversity：0.0688 and 0.0198，for A. yunnanensis and A. formosana. respectively)．A high degree of diferentiation among populations was detected in A．yunnanensis(0.76ll，0.7503 and 0.7526 for AMOVA，Nei’S coefficient of diferentiation(G_ST) and Shannon inform ation index，respectively)．It is suggested that the historical factors，including severe bottleneck and subsequent genetic drift during Quatemary glaciations and fragmentation in postglaciation，small population sizeandlow seedling establishment would have contributed to such a population genetic structure in A．yunrumensis．Based on these results，strategies are proposed for the genetic conservation and management of A．yunnanensis