连香树科及其近缘植物matK序列分析和系统学意义

测定和分析了连香树科(Cercidiphyllaeeae)、交让木科(Daplmiphyllaceac)、金缕梅科(Hamamelidaceae)代表植物的叶绿体marK序列(5′端31bps除外)，以木兰属作为外类群，应用邻接法构建分子系统树，结果表明：连香树科与水青树科的亲缘关系较远。连香树科、交让木科和金缕梅科形成了一个自展数据支持率(bootstrap)为100％的单系类群，其中金缕梅科枫香属(Liquidambar)、红花荷属(Rhodoleia)和金缕梅属(Hamamelis)虽构成了一个单系类群，但自展数据支持率仅为68％；连香树科与交让木科构成的单系分支自展数据支持率仅为53％。由于连香树科、交让木科、金缕梅科之间的进化距离相当短，表明这3个科之间亲缘关系密切，内部分支的自展数据支持率不高，表明它们之间准确的亲缘关系有待进一步研究。本研究结果与rbcL、aptB、18S rDNA序列分析结果相似，但自展数据支持率更高，表明marK序列分析可应用于较高等级分类群系统发育关系的研究。

Phylogenetic Affinities of Cercidiphyllaceae Based on matK Sequences

To further resolve the phylogenetic affinities of Cercidiphyllaceae,matK gene sequences generated for Tetracentraceae,Daphniphyllaceae,Cercidiphyllaceae and Liquidambar,Rhodoleia and Hamamelis of Hamamelidaceae,were analyzed using Neighbor-Joining method with Magnolia as an outgroup.The matK consensus tree displays similar topology to those of rbcL,atpB,and 18S rDNA sequences analyses respectively and combined with greater phylogenetic resolution.It shows that Cercidiphyllaceae,Daphniphylliaceae and Hamamelidaceae formed a robust clade,but relationships among them are not resolved;the phylogenetic relationships of Tetracentraceae to Cercidiphyllaceae are not so closed as traditional treatment.Thus,several lines of evidence,derived from both the chloroplast genome and 18S rDNA sequences,suggest the presence of considerably phylogenetic affinities between Cercidiphyllaceae,Daphniphyllaceae,and Hamamelidaceae,further information on some other quickly-evolved genes are needed to resolve phylogenetic relationships among them.The study corroborates the idea that matK sequences have potential in resolving phytogeny at family level.