Analysis of Genetic Structure of Magnolia sprengeri Populations Based on ISSR Markers

Magnolia sprengeri is an important ornamental plant species.In this study 8 ISSR primers were used to examine the genetic diversity and genetic structure of 9 natural M.sprengeri populations which included 71 individuals,collected from Shaanxi,Hubei,Chongqing of China which belong to the main distribution area.A total of 207 valid loci were obtained,of which 195 were exhibited polymorphism.The percentage of polymorphic bands(PPB)were 94.20% at species level and 43.64% at population level,and the mean diversity estimated with Nei's index(H)and Shannon's information index(I)was 0.171 9 and 0.288 2 at species level,and 0.128 4 and 0.198 8 at population level,respectively.Analysis of molecular variance(AMOVA)demonstrated that the proportion of genetic variation was 68.10%(P 0.001)within population,and 31.90%(P 0.001)among populations.The differential index(G ST)among the populations was 0.257 0.All these results indicated that there was a significant genetic differentiation both within and among the populations.The gene flow(N m)among populations was 1.445 6 and the genetic distance among 9 populations was 0.040 0.The UPGMA cluster analysis divided the 9 populations into 3 major groups,which was consistent well with the geographical distribution and floral characters of most of the populations except for some transitional populations.