松科系统发育的分子生物学证据

PHYLOGENY OF THE PINACEAE EVIDENCED BY MOLECULAR BIOLOGY

运用PCR方法分别从松科8属、9种植物中扩增出一长约2550hp的cpDNA片段,这一片段包括rbcL、trnR、部分accD及基因间的非编码区(相对于黑松cpDNA中的同源片段而言)。运用18种限制性内切酶对这一cpDNA片段进行酶切分析,共获得86个酶切位点,其中54个为变异位点。运用PAUP(version 3.1.1)和Mega(version 1.01)软件对数据进行分析,结果Wagner简约树和Neighbor-joining树反映出的松科系统发育关系基本一致:银杉属、松属、黄杉属和落叶松属形成一个单系群,且银杉属与松属的亲缘关系更近于与另外二属的关系,但这一结果未得到Bootstrap分析的较强支持;落叶松属近缘于黄杉属;冷杉属近缘于油杉属。此外,松科中的冷杉亚科和落叶松亚科均不是单系类群,将松科划分为冷杉亚科、落叶松亚科和松亚科三个亚科的系统(郑万钧,傅立国,1978)是不自然的。

The molecular phylogeny of the Pinaceae represented by nine species of eight genera was investigated through PCR-RFLP analysis of a cpDNA fragment, which was approximately 2550 bp long and homologous with the DNA fragment from the upstream of rbcL to part of accD in cpDNA of Pinus thunbergii Identified by 18 restriction endonucleases were 86 recognition sites, of which 54 were polymorphic. The restriction site data were analyzed with PAUP (version 3.1.1) and Mega (version 1.01). As a result, the most parsimonious Wagner tree constructed by branch-and-bound search is similar to the neighbor-joining tree in topology. Cathaya, Pinus, Larix and Pseudotsuga form a monophyletic group, and Larix is closely related to Pseudotsuga Cathaya is more closely related to Pinus than to Pseudotsuga and Larix, but the close relationship between Cathaya and Pinus is not well supported by the bootstrap test. Abies has a close relationship to Keteleeria Moreover, the system proposed by Zheng and Fu (1978) that the family Pinaceae was divided into three subfamilies, i.e., Abietoideae, Laricoideae and Pinoideae, is artificial, because the former two are not monophyletic.