摘要
采用ISSR分子标记技术 ,对江苏泰兴、美国纽约的栽培银杏 (Ginkgobiloba)群体和中国 3个可能为野生的银杏自然群体 (浙江西天目山、贵州务川、湖北大洪山区 )的遗传多样性水平和群体遗传结构进行了研究。用 13个引物对 5个群体共 66个样品进行扩增 ,共得到 88个清晰的扩增位点 ,其中多态性位点 62个 ,多态位点百分率 (PPB)为 70 .45 %。POPGENE分析结果表明 :与其他裸子植物相比 ,银杏具有丰富的遗传变异 (He=0 .2 40 8;Ho=0 .3 5 99)。贵州务川群体的遗传多样性水平最高 (PPB =5 6.82 % ,He=0 .2 0 89,Ho=0 .3 0 87) ,江苏泰兴栽培群体(PPB =3 4.0 9% ,He=0 .12 69,Ho=0 .185 8)和美国纽约的栽培群体 (PPB =2 3 .86% ,He=0 .0 884,Ho=0 .13 12 )的遗传多样性水平较低。Nei’s遗传多样性分析和AMOVA分析表明 ,3个可能的自然群体间出现了一定程度的遗传分化(Gst=0 .1476,Фst=14.2 6% )。群体间一定程度的遗传分化可能是人为选择压力和基因流障碍引起的。根据Nei’s遗传距离矩阵分别构建了群体间和个体间的遗传关系树状图。由UPGMA聚类分析可知 ,贵州务川群体与浙江西天目山群体优先聚类 ;美国纽约群体与湖北大洪山群体具有较近的亲缘关系 ,它们可能为同一野生群体的后裔。通过对银杏群体遗传结构的分析?
Ginkgo biloba, now unique in the Ginkgopsida, is referred as a “living fossil” plant. As a wild species, Ginkgo biloba is endemic to China. ISSR analysis was conducted on the possible natural populations (Tianmushan, Wuchuan, and Dahongshan ) and the cultivated populations (Taixing and New York) in order to investigate the genetic diversity and the genetic structure of the populations. Out of 100 ISSR primers, 13 generated highly reproducible and stable DNA fragments. Using these primers, 88 discernible DNA fragments were produced. Of these, 62 (PPB = 70.5%) were polymorphic loci, which indicated that high levels of genetic variation existed in the possible natural populations. The result of POPGENE analysis indicated that the level of genetic variation of Ginkgo biloba (H e = 0.2408; H o = 0.3599) was higher than other endangered or relict gymnosperms. The Wuchuan population possessed the highest level of genetic diversity(PPB = 56.82%,H e = 0.2089,H o = 0.3087),while the cultivated populations, Taixing(PPB = 34.09%,H e = 0.1269,H o = 0.1858) and New York(PPB = 23.86%,H e = 0.0884,H o = 0.1312), exhibited lower levels of genetic diversity than the possible natural populations (Tianmushan, Wuchuan and Dahongshan). Nei's genetic diversity analysis and analysis of molecular variance (AMOVA) showed that there was a certain level of genetic differentiation (G st = 0.1476, Ф st = 14.26%) among the three possible natural populations. Some differentiation may be caused by human selective pressures and barriers to gene flow. The dendrograms of genetic relationships among populations and among individuals were constructed based on Nei's genetic distance. The Wuchuan and Tianmushan populations clustered in a clade. Close relationship was revealed between the New York and Dahongshan populations, which means that they are likely the offspring of the same natural population. The combined results of the analysis of population genetic structure and community investigation suggest that Wuchuan may be a natural population. Based on ecological and genetic information available for Ginkgo biloba, two management strategies are proposed. The first would consist of an in situ conservation plan that defines conservation areas free from significant disruption for the genetically most diverse population and the optimal habitat (namely Wuchuan). The second would be to cross-transplant adult plants or seedlings mutually among populations in order to enhance the gene flow. By this means, the genetic diversity resources of the species can be preserved to the greatest extent.
出处
《生物多样性》
CAS
CSCD
2003年第4期276-287,共12页
Biodiversity Science
基金
国家重点基础研究发展规划项目 (G2 0 0 0 0 4680 6)
