English

Abstract

    A molecular investigation on the species of Populus belonging to sectionTacamahaca was undertaken with the aim of inferring genetic relationships within the section. The ISSR and cpDNA RFLP-based UPGMA analyses were performed for seven Populus species, with 50 specimens representing 10 accessions from southeastern Qinghai-Tibetan Plateau, China. The results provided molecular evidence suggesting that Populus schneideri is highly genetically similar toPopulus kangdingensis, as also indicated by previous studies with respect to their morphological characters. Similarly, the combination of cpSSR and nuclear SSR analyses showed that Populus trinervis and Populus simonii have a close genetic affinity, indicating their closed sister relationships. Although Populus yunnanensisis distinct from the other species based on nuclear ISSR analysis; it formed a clade with P. simonii and P. trinervis. This reflects similar maternal phylogeny among the three species. In addition, the cluster analyses clearly showed a close relationship among accessions of the same species and suggested monophyly inPopulus przewalskii and Populus cathayana. Our results demonstrated that the combination of cpDNA-RFLP and ISSR molecular markers enables a clear estimation of genetic relationships among Populus species and they provided information for preliminary conclusions that will be helpful in guiding future research.   Key words: Populus, section Tacamahaca, genetic relationships.