trnK基因5′端内含子区序列在榆科(广义)系统发育研究中的应用

The utility of trnK intron 5′ region in phylogenetic analysis of Ulmaceae s.l.

本文测定了广义榆科Ulmaceaes.l.及其近缘类群的trnK基因 5′端内含子区序列。在尝试利用该内含子区进行榆科系统发育研究的同时 ,探讨了其在植物系统学研究中的应用前景。利用PAUP软件进行的系统发育分析仅得到 1棵最简约树。该简约树的树长为 6 6 5步 ,其一致性指数 (CI)和保持性指数(RI)分别为 0 .771 4和 0 .796 5。分析结果表明 :广义榆科为多系群 ;狭义榆科Ulmaceaes.str.为荨麻目Urticales其他类群的姊妹群 ;大麻科Cannabacea嵌在朴科Celtidacea中 ,即朴科为一并系群 ;系统位置有争议的 2个属———白颜树属Gironniera和糙叶树属Aphananthe与朴科类群聚为一支。本研究还表明trnK基因 5′端内含子区序列分析在植物较低分类等级 (如近缘属间 ,属下种间 )

The sequences of chloroplast trnK intron 5′ region were determined for seven genera of Ulmaceae s.l. (12 species), two genera of Cannabaceae, two of Moraceae and one genus from each of the three families, i.e., Urticaceae, Eucommiaceae and Malvaceae. The aligned sequences used in PAUP analyses were 805 bp, and the maximum parsimony analysis resulted in a single most parsimonious tree with tree length=665, CI=0.7714 and RI=0.7965. The topology of the tree is relatively strongly supported by the bootstrap test and congruent with those generated from rbcL sequence analysis and cpDNA restriction site analysis. The phylogenetic tree indicated that Ulmaceae s.l. is polyphyletic, and that the monophyletic Ulmaceae s.str. is sister to the other Urticales taxa. Cannabaceae, represented by Humulus and Cannabis, is nested within Celtidaceae, revealing that Celtidaceae is a paraphyletic group. Gironniera and Aphananthe are both clades of Celtidaceae. The study also suggested that the trnK intron should be suitable for phylogenetic analyses at intergeneric or interspecific levels.