Study On Cytology And Chromosome Evolution Of Some Species Primula In Hengduan Mountains

Hengduan Mountains(HDM)in the southwest of China,is one of the most important biodiversity center.For its complicated geological history,diversifed habitats and climatic conditions,this region holds very rich species diversity and unique,where is an ideal area to study species differentiation and formation.This area is also the center of modern distribution and diversity of the genus Primula.In this paper,we selected 22 pupulation of 13 species Primula,focus on cytology and flow cytometry study,its purpose is to provides cytological evidence for the understanding the origin and evolution of Primula in this region.The main results were as follows:1.The cytological data of 7 species : P.sinoplantaginea,2n = 22;P.chionantha,2n = 22;P.agleniana,2n = 22;P.gemmifera var.amoena,2n = 20;P.forrestii,2n = 22;P.bullata,2n = 20;P.blinii,2n = 18,are reported for the first time.Besides,we studied 22 populations with chromosome basic numbers of x = 9,10,11,12,the 2n = 18,20,22,24,and the results showed all of species were diploidy,and their karyotypes were 1A,1B,2A,2B.2.The ploidy and genome size were determined by flow cytometry.According to the flow cytometry result,all species were diploidy.The genomic values of Primula showed that the genome values ranged from 2157.38 Mbp to 9394.12 Mbp,the 2C values from2.21-9.61 pg.3.The statistical results showed that the number of chromosomes varies greatly with obviously aneuploidy changes,but all are diploid in HDM.According to the global ploidy statistics,the proportion of the diploid was also more than 50%,and the polyploidy ratio was not high.It shows that the phenomenon of polyploidy is not the adaptation mechanism of the Primula,both in HDM or the whole word.