摘要:
采用ISSR分子标记技术,对延龄草7个自然居群的遗传多样性水平和遗传结构进行了研究.用12个引物对7个居群共105个样品进行了扩增,共得到135条清晰的扩增位点,其中多态性位点46个,多态位点百分率(PPB)为34.07%.POPGENE分析结果表明:同其他一些濒危植物相比,延龄草具有较低的遗传多样性(He=0.0759,Ho=0.1200).卧龙居群的遗传多样性水平最高(PPB=18.52%,He=0.0417,Ho=0.0684),大坝子居群的遗传多样性水平最低(PPB=8.89%,He=0.0220,Ho=0.0348).Nei's遗传多样性分析和AMOVA分析表明:7个自然居群间出现了一定程度的遗传分化(Gst分别为0.5554和0.5253),可能是基因流障碍和遗传漂变引起的;而居群间的限制性基因流(Nm=0.4002)可能由种子的有限传播距离、居群的地理隔离或自交等因素导致.通过对延龄草居群遗传多样性和遗传结构的分析,结合群落学调查研究,该文提出了一些保护策略.
Abstract:
Using inter-simple sequence repeat (ISSR) analysis, the genetic diversity and the genetic structure of 7 natural populations of Trillium tschonoskii were investigated. Twelve ISSR primers generated highly reproducible and stable DNA fragments. Using these primers, 135 discernible DNA fragments were produced. Of these, 46 (PPB= 34.07%) were polymorphic loci, which indicated that low levels of genetic variation existed in the populations. The result of POPGENE analysis indicated that the level of genetic variation of T. tschonoskii (He=0.075 9,Ho=0.120 0) was lower than that of other endangered plants. The population in Wolong possessed the highest level of genetic diversity (PPB=18.52%,He=0.041 7,Ho=0.068 4), while that in Dabazi exhibited the lowest levels of genetic diversity (PPB=8.89%, He=0.022 0, Ho=0.034 8). A high level of genetic differentiation among populations which might be caused by barriers to gene flow and genetic drift was detected based on Nei's genetic diversity analysis(0.555 4) and the analysis of molecular variance (0.525 3). Restricted gene flow (Nm=0.400 2) among populations may result from several factors, such as low seed dispersal, geographical isolation of population and selfpollination. Based on ecological and genetic information available for T. tschonoskii, some conservation strategies are proposed.
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