Abstract: Genetic diversity in the five natural populations of Rhododendron fortunei in Zhejiang province of China were analyzed using inter simple sequence repeat ( ISSR) molecular markers. A total of 170 loci, 150 of which were polymorphic ones, were detected in natural populations of Rhododendron fortunei using 12
ISSR primers. Total percentage of polymorphic loci ( P, % ) was 88.24% in the species, while Shannon's information index ( I) and Nei's gene diversity ( h) were 0.4317 and 0.2848, respectively. These indicated that the genetic diversity of Rhododendron fortunei was relatively high. In the contrary, the genetic diversity at population level of Rhododend ron fortuneiwas relatively low. The mean value of P% , I and h were 48.23% ,0.2682 and 0.1818, respectively. Analysis of molecular variance (AMOVA) demonstrated that the among population component accounted for 40.03% of the total variations, while the within population component accounts for 59.97%. The genetic differentiation was relatively high and the gene flow was low ( 0.8824 ).
These results suggested that population isolation and inbreeding regression may play the main roles in the genetic differentiation among Rhododendron fortunei populations. The pair-wise mean genetic distance among populations was 0.1755. The clustering analysis showed that KCS population and TTS population were in one group, FYS population and BSZ population in another group, and GK population separated from all the other populations in the dendrogram.

Key words: Rhododendron fortunei, Natural population, Genetic diversity, Genetic differentiation, ISSR