Relationship Among Species Of Sect. Populus Using Rapd Markers

Sect. populus species are adaptable and widely distributed in china, which have important production significance. Many countries and regions have introduced and cultivated them because of their fast growth, adaptability and widly using. They are important for shelterbelt, water and soil conservation, forestation and timber. According to traditional classification, Sect. populus are divided into Subsect. Albidae Dode and Subsect. Trepidae Dode, among them, P. alba L. and P. alba var. pyramidalis Bge(the variant of P. alba L) are the representative species for Subsect. Albidae Dode and P. davidiana Dode, P. adonpoda Maxim are the representative species for Subsect. Trepidae Dode. Another three natural hybrid are P. canescens(Ait.) Smith, P. tomentosa Carr and P. hopeiensis Hu et Chow, accord to morphology, which respectively classified into Subsect. Albidae Dode [P. canescens(Ait.) Smith, P. tomentosa Carr] and Subsect. Trepidae Dode(P. hopeiensis Hu et Chow).Sect. populus are variety and widely distributed, there were many hybridization and genetic variation happened between species, which made the origin and relationship are still controversial in part of Sect. populus species. In this experiment, random amplified polymorphic DNA markers were used to analysis the relationship among species in Sect. populus. This study will provide a reference to Sect. populus species about the taxonomy, hybrid origin in molecular level. The main results are as follows.1. Established a effective method to extract the genome DNA from the poplar for RAPD.2. 26 primers were selected from 90 primers for RAPD. In these 26 primers, OPA05 produced the least number of bands (only 3 bands) and S24 produced the largest number of bands (up to 14). Among the total of 222 bands, there are 200 bands (90.09%) were detected to be polymorphic, which revealed the complexity and diversity of Sect. populus species'genetic background.3. The phylogenetic dendrogram generated from UPGMA demonstrates that the diversity between all species is larger than the clones from every species. All these 10 species were divided into two categories: The first category including P. davidiana Dode, P. adonpoda Maxim, and P. hopeiensis Hu et Chow; and the second category including P. tomentosa Carr, P. alba , P. canescen Smith, P. alba var. pyramidalis Bge, P. alba×P. tomentosa Carr, P. alba×P. alba var. pyramidalis Bge and P. alba×P. glandulosa.The genetic distances demonstrate that P. canescens(Ait.) Smith is closer to P. alba L (GD=0.2291) than P. davidiana Dode (GD=0.5608), it is consistent with the traditional classification that classified P. canescens(Ait.) Smith into Subsect. Albidae Dode. The five different clones of P. tomentosa Carr were divided into 2 groups and they all closer to P. alba L (GD=0.4566) than P. davidiana Dode (GD=0.5569), it is demonstrates the P. tomentosa Carr is a hybrid origin species. The genetic distance between P. alba var. pyramidalis Bge and P. alba L are very close (GD=0.2899), which is the second only to the distance between P. alba var. pyramidalis Bge and P. alba×P. alba var. pyramidalis Bge, which supports the view that P. alba var. pyramidalis Bge as variant of P. alba L. P. hopeiensis Hu et Chow are closest to P. davidiana Dode (SC=0.6840), it is consistent with the traditional classification that classified P. hopeiensis Hu et Chow into Subsect. Trepidae Dode. The three artificial hybrids are closer to Subsect. Albidae Dode than Subsect. Trepidae Dode, P. alba×P. tomentosa and P. alba×P. glandulosa are the closest in the three artificial hybrids.