Molecular systematical Studies of Cupressaceae and Taxodiaceae using DNA sequence information

利用叶绿体atpA、petA、rbcL和rpo 3基因的DNA序列信息，阐明了柏科和杉科两个科的分子进化。主要结果如下：（1）柏科和杉科的分子系统学研究表明，柏科和杉科由5个分支组成，柏科是杉科的一个分支。(2)在petA基因上，钝头Chamaparis obtusa和钝头Chamaparis var.福尔摩沙。利用这些信息，这两个物种被正确识别。(3)在Chamaaparis属的亲缘关系中，阿拉斯加柏树（Chamaaparis nootkatensis）与其余6个物种/变种的亲缘关系较远。该属分为三个分支。(4)利用DNA信息对莱兰柏（Cupressocyparis leylandii）的杂种关系进行了验证。我们发现了莱兰柏的核基因组起源于柏科的蒙特里柏（Cupressus macrocarpa）和阿拉斯加柏（Alaska cypress）的分子证据，证明该种为杂种起源。(5)预测了阿拉斯加扁柏在Chama-paris属中的系统位置。通过分子系统发育树分析，发现该种应归属于柏木属。(6)柏科分为两个单系分支，分布于北方和南半球。南半球的属起初是分歧的。崖柏属和崖柏属是次生分离的，柏属和圆柏属是新形成的。(7)水杨梅属是柏科中分化最晚的一个属，其种类的辐射时间较短。

The molecular evolution of two families, Cupressaceae and Taxodiaceae, was elucidated using DNA sequence information on four chloroplast DNA genes, atpA, petA, rbcL, and rpo3. The principal results are as follows :(1) The molecular phylogeny of families Cupressaceae and Taxodiaceae revealed that they consisted of five clades and that family Cupressaceae was comprised within family Taxodiaceae.(2) In petA gene, the sequence polymorphism was recognized between Chamaecyparis obtusa and C.obtusa var. formosana. Using this information, the two species came to be identified correctly.(3) In the phylogeny of the genus Chamaecyparis, Alaska cypress (Chamaecyparis nootkatensis) was distant-related from the remaining six species/variety phylogenetically. This genus was divided into three clades.(4) The hybridity of Leyland cypress (x Cupressocyparis leylandii) was verified based on DNA information. We found the molecular evidence that the nucleic genome of Leyland cypress originated from Monterey cypress (Cupressus macrocarpa) and Alaska cypress in the Cupressaceae and that this species is of hybrid origin.(5) Systematical position of Alaska cypress was predicted in the genus Chamaecyparis. A new finding that this species should be classified as a member of the genus Cupressus was revealed based on molecular phylogenetic trees.(6) The family Cupressaceae was divided into two monophylic clades distributed in the northern hemisphere and the southern hemisphere. The genera of the southern hemisphere diverged at first. The genera Thujopsis and Thuja secondary separated, and the genera Cupresus and Juniperus were newly formed.(7) The genus Callitris was the latest-diverged in family Cupressaceae and the species of this genus was radiated in a relatively short term.