Karyotype analysis of eight populations of six Salvia species in the Hengduan Mountains

Salvia is the largest genus of the Lamiaceae. Several species of Salvia are used as traditional Chinese medicine, as well as ornamental species. To explore the evolution pattern of species in Hengduan Mountains at the cytological level and to discuss the taxonomic relationship between morphological taxonomy and molecular systematics, based on extensive collection of chromosome literature, the karyotypes of six species (eight populations) of Salvia collected from Hengduan Mountains were analyzed by using conventional plant pressing method, and the chloroplast phylogenetic trees of Salvia distributed in China were constructed. The statistical results were as follows: (1) About 23% of the chromosome data of Salvia was reported all over the world, in which the chromosome reporting rate of Salvia in China was 32.10%. The reporting rate of Salvia in Hengduan Mountains was 40.54%. (2) The chromosome basic number of Salvia were mainly x=8 and x=11, and the chromosome cardinal numbers of Salvia plants distributed in China were x=8. The experimental results were as follows: (1) The karyotype data of S. wardii was reported for the first time. (2) The diploid population of S. evansiana was found for the first time in Deqen, Yunnan. The chromosome evolutionary association analysis was carried out by combining cytological data with chloroplast evolution tree, and it was demonstrated that polyploidy might not be the main mechanism of Salvia adapting to high altitude environment. It showed that polyploid was not the main evolutionary pathway of Salvia plants species formation, but mainly at the level of diploid. So we speculated that the doubling of genome might be one of the reasons for the inconsistency between species morphology taxology and molecular phylogeny taxology. This study enriches the chromosome karyotype data of Salvia in Hengduan Mountains, discusses the evolutionary relationship of chromosome characteristics combined with regional molecular phylogenetic tree, has made exploration for further study of the karyotype evolution of Salvia species in the future, and complements the basic data for the deduction and analysis of the chromosome cardinal number of ancestral species.