大青杨及其近缘种的遗传变异和系统关系研究

THE GENETIC VARIABILITY AND PHYLOGENETIC RELATIONSHIP IN POPULUS USSURIENSIS KOM.AND ITS RELATIVES

对杨属青杨派主要树种大青杨、甜杨、香杨和马氏杨种间及种内遗传变异进行了ＲＡＰＤ检测，结果表明：７个随机引物对４个树种ＤＮＡ扩增产物绝大部分呈现为单型性，而有３个引物扩增产物显示出丰富的种间多型性；所有引物均在４个树种内扩增出不同程度的多态性。统计分析建立的系统树还说明了４树种可能的亲缘关系及系统发育史，同时，各树种内也均存在着遗传多样性。这对今后进行这些树种的遗传改良具有重要意义。此外还得出：分子水平分类的结果与经典分类一致：４个树种中马氏杨出现最早，甜杨次之，香杨再次之，大青杨最晚；大青杨与香杨亲缘关系最近，因此，以往认为大青杨与甜杨亲缘关系最近的说法有必要重新审视。

RAPD analysis was applied to the major species in the section Tacahamac of the genus Populus,such as P.suaveolens Fisch.,P.ussuriensis Kom.,P.Koreana Rehd.and P.maximowiczii Henry in order to assess the degree of genetic variability between and within these species.Most of the amplification products generated from the four species using the seven primers are monomorphic,but three out of the 7 tested appeared to produce a considerabledegree of polymorphism at the interspecific level and all the tested primers could produce varying extent of polymorphism at the interspecific level within all the four species.A dendrogram displaying hierarchial associations was generated using NT-SYS computer programme and more apparently revealed genetic variability between and within the four species.The result is of significance to the future improvement of these species.In addition,the resulting analysis was in broad agreement with previous classification of the species studied,confirming the validity of the method. The results showed that P.Koreana Rehd.appear as the closest relative of P.suaveolens Fish.,followed by P.ussuriensis Kom. and further away, P.maximowiczii Henry.questioning the current classification, in which P.suaveolens Fisch.and P.ussuriensis Kom.share the closest relationship among the species in the section Tacqhamac.