Molecular Systematics Analysis Of Astragalus L. In Qinghai-Tibet Plateau

In this research, Astragalus in Qinghai-Tibet Plateau are used as materials based on classical taxonomy. Analyze the ITS amplification sequences and trnL-F amplification sequences. ITS sequences are sequencing one-way by primers. TrnL-F sequences are sequencing two-way by primers. The sequence alignments are finished by ClastalX2 and individual base are corrected manually. ITS sequences and trnL-F sequences are both select Caragana as outgroup. The phylogenetic trees are built by PAUP4.0 with MP. Combination of morphological characteristics and geographical distribution, we can draw the following conclusions:1. Subgen. Pogonophace taxton is an independent and natural taxon. It is reasonable as an independent genus and occupies a unique geographical and ecological distribution area. The morphological characterizations are uniform. Flora of China follows the taxonomic treatment. From the phylogenetic trees, we can see that the Subgen. Pogonophace taxton are identical. Though individual materials are out of the ordinary, it is identical on the whole and has strong bootstrap supports. It supports this kind of taxon idea.2. The Sect. Polycladi and the Subgen Hypoglottis should be in the same section. From the morphological characterization, their stipules are different. In Sect. Polycladi, the stipules are free from petiole or nearly so. In Subgen Hypoglottis, all or those of lower leaves are high connate behind stem. From the phylogenetic trees, this two subgenera are identical and there are no clear boundaries. It supports the idea of Flora of China that the two subgenera should be in the same section. So it is unreasonable based on the morphological characterization only.3. Most spaces in Subgen. Pogonophace should be transferred to Phyllolobium from Astragalus and other Subgenera in Astragalus are not supported. Section in Astragalus should be revised. In the Phylogenetic trees, the taxon of Sect. Polycladi are identical with Sect. Komaroviella and Sect. Poliothris. So they should be united to one group.4. The subgenera with medifixed hairs may be derived from Subgen. Astragalus or Subgen. Hypoglottis. It shows the xerophytes direction and has adaptive differentiation in the arid and semi-arid habitats. Subgen. Astragalus or Subgen. Hypoglottis are more diverse according to the habitat, and evolution mainly adapt to the Alpine-cold habitats.