不同地理种群巴山榧树及近缘种叶绿体trnL-trnF序列的分析

Sequences Analysis and Comparison of trnL-trnF of Geographical Populations of Torreya fargesii(Taxaceae) and its Closely Related Species

本文运用PCR产物直接测序法对巴山榧树10个地理种群的trnL-trnF序列进行了测定,并调用GenBank中6个近缘种的trnL-trnF序列,选用MEGA 4.1软件对巴山榧树不同地理种群及近缘种间的trnL-trnF序列进行分析。结果表明,巴山榧树10个地理种群间的遗传分化程度较低,只有34个变异位点,1个信息位点;7个近缘种间的遗传分化较显著,有75个变异位点,30个信息位点。聚类分析将巴山榧树10个地理种群与6个近缘种聚为2个分支,巴山榧树、云南榧和日本榧树聚为一支,榧树、长叶榧树、佛罗里达榧和加州榧聚为另一个分支。trnL-trnF序列系统树不支持将榧树属分为皱乳榧组和榧树组;赞同将云南榧并入巴山榧树,或作为巴山榧树的变种处理;不支持将巴山榧树和云南榧合并在榧树下作为变种的处理意见。

Chloroplast trnL-trnF intergenic spacer sequences of 10 geographical populations of Torreya fargesii were sequenced by using PCR product sequencing method, trnL-trnF sequences of 6 closely related species （T. far- gesii var. yunnanensis, T. nucifera, T. grandis, T. jackii, T. taxifolia and T. californica） were retrieved from Gen- Bank, and MEGA 4.1 was used to analyze the trnL-trnF sequences among these geographical populations of T. far- gesii and its closely related species. The results indicated that the genetic differentiation among these geographical populations of T. fargesii was low, with only 34 variable sites and 1 parsimony informative sites. But the genetic differentiation between 7 closely related species was significant, with 75 variable sites and 30 parsimony infor- mative sites. Based on the results of cluster analysis, 10 geographical populations of T. fargesii and their closely related species could be divided into two major branches. T. fargesii, T. fargesii var. yunnanensis and T. nucifera, were clustered into branch I, while T. grandis, T. jackii, T. taxifolia and T. californica were in branch Ⅱ. The trnL-trnF phylogenetic tree does not support that the Torreya was divided into Section Ruminatae and Torreya. This study supports that T. fargesii var. yunnanensis was combined into T. fargesii, or treated as a variant of T. fargesii, and argues against the classification proposition that T. fargesii and T. fargesii var. yunnanensis were combined into T. grandis.