生物多样性 ›› 2006, Vol. 14 ›› Issue (4): 315-326.DOI: 10.1360/biodiv.060053

• 论文 • 上一篇    下一篇

湖北野生天麻的遗传分化及栽培天麻种质评价

吴会芳, 李作洲*, 黄宏文*   

  1. (中国科学院武汉植物园, 武汉 430074)
  • 收稿日期:2006-03-13 修回日期:2006-05-10 出版日期:2006-07-20 发布日期:2006-07-20
  • 通讯作者: 李作洲,黄宏文

Genetic differentiation among natural populations of Gastrodia elata (Orchidaceae) in Hubei and germplasm assessment of the cultivated populations

Huifang Wu, Zuozhou Li*, Hongwen Huang*   

  1. Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074
  • Received:2006-03-13 Revised:2006-05-10 Online:2006-07-20 Published:2006-07-20
  • Contact: Zuozhou Li,Hongwen Huang

摘要: 采用7条ISSR引物对天麻(Gastrodia elata) 8个自然居群和6个人工栽培居群共483个样本的居群遗传多样性进行了初步检测, 共检测出清晰、重复性好的DNA带77条, 其中64条为多态性带, 总多态位点百分比PPB=83.12%。遗传多样性分析结果表明: 天麻自然居群的遗传多样性参数分别为:多态位点百分比PPB=59.09%,有效等位基因数Ae =1.29,Nei’s遗传多样度H=0.176,Shannon’s多态信息指数I=0.270,明显高于人工栽培居群(PPB= 35.71%,Ae=1.16,H=0.100,I=0.155), 揭示出栽培居群存在明显的遗传基础狭窄和遗传均质性问题。UPGMA聚类分析表明, 自然居群与栽培居群存在明显的分化而分别聚为两大类群。自然居群间基因分化系数GST=0.2558, 与AMOVA分析所揭示的居群间遗传变异量占总变异的27.25%的结果相近, 说明天麻自然居群间亦存在一定程度的遗传分化; 居群间基因流(Nm)为1.4547, 相对较弱, 可能对自然居群的遗传分化有一定影响。自然居群聚类结果显示出一定程度的地理区域聚类趋势, 但Mantel检验表明自然居群间遗传距离与地理距离并不存在显著相关(r=0.1669, P=0.2110), 揭示出天麻自然居群的分化现状可能是其生活史特性、地理隔离与人为破坏综合作用的结果。栽培居群的遗传均质化趋势, 揭示了引种驯化的瓶颈效应和长期无性繁育所导致的遗传多样性丧失, 也反映出栽培天麻种质的遗传基础狭窄。而栽培居群与自然居群间存在着明显的遗传分化, 反映天麻栽培居群与自然居群间可能存在基因流的阻断。

关键词: 垂直格局, 物种多样性, 小五台山, 北坡

AbstractGastrodia elata (Orchidaceae) is a rare and endangered medicinal plant. Seven ISSR primers were used to examine population genetic parameters of 483 samples across eight natural populations and six cultivated populations of G. elata. The seven primers amplified a total of 77 unambiguous and reproducible bands, among which 64 bands were polymorphic and the percentage of polymorphic loci was PPB=83.12%. The results showed that genetic variation in the natural populations was significantly higher than that in the cultivated populations (PPB=59.09% vs. PPB=35.71%, Ae=1.29 vs. Ae=1.16, H=0.176 vs. H=0.100 and Shannon’s I=0.270 vs. I=0.155), suggesting that the cultivated populations are narrowly genetic-based and genetically uniform. UPGMA cluster analysis showed that natural populations and cultivated populations were distinctly separated into two groups. Coefficient of genetic differentiation among eight natural popula-tions was 0.2558 (GST) which was well in accordance with the result by AMOVA analysis (27.25% of the to-tal genetic variation resided among populations), indicating that natural populations were genetically differ-entiated to a certain extent. Gene flow among natural populations was relatively weak (Nm=1.4547), which might have caused the genetic differentiation among the populations. It is interesting to note that natural populations tended to cluster by geographical locations as revealed in UPGMA dendrogram, while the Mantel test showed no significant correlation between genetic and geographic distances among natural popula-tions(r=0.1669, P=0.2110). This incongruence suggested that the current genetic differentiation among natu-ral populations might have resulted from combined effects, including those of life history traits, geographical isolation and human disruption. The genetic uniformity found in cultivated populations might reflect the loss of genetic diversity caused by a genetic bottleneck during human domestication and clonal reproduction over generations. The narrow genetic base as revealed in cultivated G. elata and the genetic differentiation be-tween cultivated and natural populations might have resulted from a cutoff of gene exchange when domesti-cation began.