根据DNA的序列资料探讨翅子树族的系统位置

采用DNA分子测序技术对梧桐科5个族30个代表种的rbcL基因及核糖体DNA的内转录间隔区ITS序列(包括ITS1、ITS2和5．8srRNA基因)进行了序列分析。使用PAUP4．0b10软件对序列进行统计和分支分析。用启发式搜索方法寻找最简约树。从严格一致性树来看，梧桐科的全部代表类群主要被分为4支，一支仅为Sterculieae所构成；一支包括Helictereae的全部代表种；一支由Byttnerieae代表种所构成；最后一支由Dombeyeae和单属族翅子树族Pterospermeae所构成。rbcL和ITS系统树的不同仅表现在族内个别代表类群的位置和族的分支方式上。分析结果表明，与Helictereae相比，翅子树属，Pterospermum与Dombeyeae有更近的亲缘关系。然而，在外部形态、内部解剖和胚胎学方面，二者之间又存在诸多差异．故支持将Pterospermum另立为Ptcrospermeae的观点。

Systematic Positions of Pterospermeae (Sterculiaceae)on the Basis of DNA Sequence Data

DNA molecular sequencing method was adopted to analyze the sequences of chloroplast gene rbcl and the internal transcribed spacers (ITS)(including ITS1, ITS2 and 5.8 s rRNA gene) of nuclear ribosomal DNA in 30 typical species of five Sterculiaceae tribes. Software PAUP4.0b10 was used to conduct statistical and ramification analysis of the sequences and the heuristic search was adopted to look for the most parsimonious trees. In light of strict consensus trees, all the typical groups of Sterculiaceae fell into four clades, one consisting of only Sterculiaceae, one containing all the typical Helictereae species, one consisting of all the typical Byttnerieae species and one composed of Dombeyeae and Pterospermeae represented by Pterospermum . The topological difference between rbc L and ITS systematic trees found expression in the positions and ramifications of some typical groups. The analysis results showed that Pterospermum and Dombeyeae were close in consanguinity compared with Helictereae. Moreover, they differed much in morphology, anatomy and embryology and thus the study support the viewpoint that Pterospermum should be re categorized as Pterospermeae.