珙桐种质资源保存样本策略的研究

珙桐 (Davidiainvolucrata) 是我国特有的珙桐科单型属植物, 起源古老, 是第三纪热带植物区系的孑遗种, 被列为国家一级保护植物。利用RAPD技术, 通过 11个多态引物对 5个天然珙桐种群的遗传多样性、种群内和种群间的遗传变异进行了研究。结果表明 :珙桐天然种群具有丰富的遗传多样性, 但群体间的差异明显, 2 6 %的遗传变异存在于群体间。研究将珙桐划分为东南部和西北部两大种源区。通过对珙桐群体间及群体内的聚类分析, 结合遗传标记的捕获曲线研究提出了珙桐种质资源保存的样本策略。原地保存可以选择甘肃文县、四川峨眉山和贵州梵净山 3个种群作为保存对象, 每个群体保存面积 3hm2 以上 ;异地保存应抽取甘肃文县、四川峨眉山、湖北神农架、贵州梵净山等 4个群体, 每个群体抽样 30个以上个体, 株间最小间距 30m以上, 共计保存 15 0个个体, 分别在东南部和西北部建立一个异地保存点。

SAMPLING STRATEGY FOR PRESERVATION OF GERM PLASM FROM DAVIDIA INVOLUCRATA

Davidia involucrata is a monotypic genus that is a relict from the tropical flora of the Tertiary Period. As a plant endemic to China, it is classified as a first-grade state protection plant. An analysis on genetic diversity and genetic variation within and among populations from five natural populations of D. involucrata was conducted using RAPD marker based on 11 polymorphic random primers. The results showed that populations of D. involucrata had rich genetic diversity, but those significant differences among populations accounted for 26% of the genetic variation. Two large provenance plots in the southeast and northwest were established for the study. Based on cluster analysis of genetic diversity of populations of D. involucrata and curve analysis of the genetic markers, we put forward a sampling strategy for the preservation of germplasm of D. involucrata. For on-site preservation, three populations should be selected for each of the following areas: Wenxian County in Gansu Province, Emeishan in Shichuan Province and Fanjingshan in Guizhou Province. Each population to be preserved should occupy a minimum 3 hm 2. Off-site preservation should sample a minimum of 30 individuals from each of the following populations: Wenxian County, Emeishan and Shennongjia (in Hubei Province) and Fanjingshan for a total of 150 individuals. Individuals should be planted at a minimum space of 30 m. Also, we suggest that two off-site preservation areas should be established: one in the southeast and one in the northwest regions of China.