由5个DNA片段推断极度濒危植物五针白皮松的系统位置

五针白皮松(Pinus squamata X．W．Li)是上世纪90年代描述的一种中国特有松树，目前野外只有立木32株，处于极度濒危状态。前人认为这个种可能是白松亚属(subgen．Strobus)的白皮松(P．bungeana Zucc．ex Endl．)与松亚属(subgen．Pinus)的云南松(P．yunnanensis Franch．)的过渡类型，并将其归入白皮松组狐尾松亚组(subsect．Balfourianae)。本文试图在前人分子系统学工作的基础上，检测五针白皮松5个DNA片段，叶绿体基因rbcL、matK、rpl20-rps18间隔区和trn V内含子以及核糖体ITS，将五针白皮松放在整个松属中探讨其系统位置。4个叶绿体基因单独分析结果和它们的联合数据分析结果以及根据ITS得到的系统树均表明，五针白皮松是白皮松亚组(subsect．Gerardianae)的一个稳定成员，其可能的姐妹群是西藏白皮松(P．gerardiana Wall．)。对白皮松亚组的地理分布作了初步探讨。

Phylogenetic Relationship of an Extremely Endangered Species, Pinus squamata (Pinaceae) Inferred from Four Sequences of the Chloroplast Genome and ITS of the Nuclear Ribosomal DNA

Pinus squamata X. W. Li, a recently_described species of the Pinaceae, is an extremely endangered pine with only 32 individuals in the wild. This species was thought to be intermediate between P. bungeana Zucc. ex Endl. of subgen. Strobus and P. yunnanensis Franch. of subgen. Pinus by the original author. We made an effort to address the question of the phylogenetic relationship of this peculiar and important species in the context of the major groups of the genus Pinus by using sequences of the rbc L, mat K genes, rpl20_rps18 spacer, trn V intron of the chloroplast genome and the nuclear ribosomal ITS region. The results of the separated analysis and the combined analysis of the four cpDNA sequences and ITS sequence indicated that P. squamata was a stable member of subsect. Gerardianae and P. gerardiana Wall. was the closest species of P. squamata phylogenetically. As a result, the causes of the distribution pattern of subsect. Gerardianae were also discussed.