Abstract: Ex-situ conservation of Oryza rufipogon genetic resources has been well done and about 6000 accessions were preserved in the National Genebank and vegetative nurseries. However, whether they could be representative for the whole genetic integrity of Oryza rufipogon has also been concerned. In this study, two populations with their in-situ and ex-situ conserved groups in Dongxiang County, Jiangxi Province, were selected to study the genetic diversity by using SSR. The results indicated that, the genetic diversity indices of in-situ and ex-situ conserved groups of Anjiashan population were 0.5000 and 0.3555, respectively. The genetic diversity index of ex-situ conserved group was only 71.1% of that of in-situ conserved group. Moreover, all ex-situ preserved samples were clustered together in the dendrogram and was one branch of the whole "tree". For Shuitaoshu population, the distance of genetic diversity index of in-situ group (0.4100) and that of ex-situ group (0.4577) was very small, and all ex-situ samples clustered together with in-situ samples. It seems that the ex-situ conserved group could be representative for the genetic diversity of the original population. However, six of the fourteen ex-situ samples were close to the samples with the successive numbers, meaning that about 42.9% ex-situ samples were redundant. Furthermore, genetic diversity study on the total samples of in-situ and ex-situ collections from above two sites also showed similar results with those of Anjiashan site. Based on the above results, it is concluded that the genetic diversities of ex-situ preserved groups used in this study can not be representative for the genetic diversities of the original populations, and thus referres that the genetic variation contained in the preserved O. rufipogon genetic resources in China is relatively low and there are some redundant samples in the genebanks. Therefore, re-collection of genetic resources of O. rufipogon and getting rid of the redundant samples based on evaluation are necessary.

Key words: Oryza rufipogon, SSR, Genetic diversity, In-situ conservation, Ex-situ conservation