Abstract: Dongxiang wild rice (Oryza rufipogon, Griff.) distributes at 28ì14N in Dongxiang County, Jiangxi Province, where is recognized to be the northernmost habitats for O. rufipogon populations in China, as well as in the World. Nine populations with total 3 hm2 distribution area were found in Dongxiang County during 1970s. However, due to expanding agricultural activities, only 2 populations named Anjiashan and Shuitaoshu were remained at present. To study the genetic diversity of the populations, 30 pairs of SSR (Simple Sequence Repeats) primers were used to amplify the selected samples and POPGENE ver1.31 statistic software was applied to cluster the SSR data. The results indicated that the genetic diversity indices within and between populations were 0.4120 (HS) and 0.0564 (DST) respectively，and the coefficient of genetic differentiation (GST) was 0.1219, meaning that the genetic variability between populations was low. The cluster analysis also showed that Shuitaoshu population is one branch of Anjiashan population, inferring that the two natural populations were once from a large population. For Anjiashan population, 3 sub-populations were formed because of the construction of the in-situ facilities (brick walls) in 1985. The same methods were also applied to analyze the genetic diversity of the sub-populations in Anjiashan population. The results showed that the coefficient of genetic differentiation (GST) was only 0.0975, the sub-populations still belonged to the same population but gene differentiation actually happened. Though the brick walls have played significant roles for the conservation of wild rice in Dongxiang, it caused the genetic differentiation among 3 sub-populations. Therefore, two aspects should be considered during designing in-situ conservation strategies for Dongxiang wild rice: (i) Anjiashan population should be effectively conserved first, and (ii) the brick wall built in 1985 should be removed and the original ecosystem should be recovered for Anjiashan population.

Key words: Wild Rice, SSR, Genetic Diversity, Genetic Differentiation, In-situ Conservation