Studies On Chromosome Variation And Its Significance On Taxonomy Of 27 Populations Belonging To 6 Species Of Saussurea DC. In The Eastern Of Qinghai-Tibetan Plateau

The genus Saussurea distribute in Asia and Europe. Most of them are annual, biennial and perennial herbs and only a few species are semishrubs. Many species in this genus are promising medicinal plants. As to the studies on Saussurea DC., much have been done concerning their pharmacological, physiological, molecular, cytological and morphological properties. However, the composition of this genus is complex and there are still some gaps in the taxonomic system under genus and their evolution. Studies on chromosome variation of Saussurea populations are of great significance for further research into the origin, phylogeny, taxonomy and exploitation of this genus. Consequently, this paper systematically investigated chromosome number, presence of B chromosome or SAT, karyotype variation, arm ratio, relatived length, and karyotypic asymmetry and geographical distribution of 27 populations belonging to 6 species of Saussurea DC. in the eastern of Qinghai-Tibetan Plateau. The results are listed as follows:1 Chromosome number of 27 populations belonging to 6 species of Saussurea DC. varied greatly, ranging from 24, 26, 28 to 32.2 The 27 populations belonging to 6 species of Saussurea DC. had large difference in karyotype. Most populations investigated in this paper had 2A karyotype, and only a few are 3A, 2B and 3B.3 A pair of B chromosomes were respectively found only in the population 13 and 16 of S. hieracioides for the fisrt time among 27 populations belonging to 6 species of Saussurea DC.4 No satellites were been found in these 27 populations belonging to 6 species of Saussurea DC.5 From the view of geographical positions, adjacent populations have not only similar but also varied karyotypes.6 Varied karyotype features indicated genus Saussurea originated early and internally diverged greatly.