Study On Phylogeny And Relationships Of The Genus Populus Natural Stand In Ergis River Watershed

A total of 83 samples belonging to 6 species from 3 sections were collected from natural stands of the genus Populus in Ergis River Watershed in this study, interspecific relationship the forming mechanism of hybrid P.canescens and the classification positions of P. ×jrtyschensis and P.albal were investigated using DNA markers and the main findings were summarized as the following.(1) The SSR analysis showed that the populus natural stands of Ergis River Watershed could be divided into two groups, one is Aigeiros and Tacamahaca, the other is Leuce, so the genetic relationship between Aigeiros and Tacamahaca was closer than that between Leu and Aigeiros or Tacamahaca. It appears that it is more variable in genetic structure of the populations of the P.laurifolia from different entironments than within the populations. In UPGMA tree, P. ×jrtyschensis and P.nigra could be clustered into one group, different from P.laurifolia, supporting the conclusion that P. ×jrtyschensis and P.nigra are the same section, In addition, P. ×jrtyschensis have the more component of P. nigra, and similar to P. nigra in stem form .(2) The similarity coefficient ranging from 0.7-0.96 within the P. alba, 0.68-0.96 within P.tremula , and 0.50-1.00 within P.canescen. The result shows that there are high level of genetic variation of P.canescens, also more among the populations than within populations.(3) Investigation showed that there is no distribution of P.canescens in the distributing range of P.tremula. so it indicated that the pattern of the hybrid between P.tremula and P.alba is that introgression occurs preferentially from P.tremula to P.alba L. via P.tremula pollew. Another reason may be the barrier of P.alba to P.tremula via P.alba pollen, such as different florescence(because elevation of two species is different). In UPGMA tree, 2 samples of P.tremula (H11, H41) are highiy homologous with P.alba E11 (from Manasi gene bank of popular ),and different from populations of P. tremula( H12 H41 H42 . H43), indicating that it is possible for P.tremula obtain P.alba pollen.(4) About the forming mechanism of hybrid P.canescens.we suggest that introgression occurs preferentially from P.alba to P. tremula different from Europe, due to the Bu'erjin populations...