原、异位保存普通野生稻种质资源的遗传多样性比较研究

 为了明确我国异位保存的普通野生稻是否能够代表原居群遗传多样性的完整性，利用SSR（简单序列重复）方法对江西省东乡县庵家山和水桃树2个普通野生稻居群的原、异位群体进行了遗传多样性比较研究。结果表明，庵家山居群原、异位保存群体的遗传多样性指数分别为0.5000和0.3555,异位保存群体的遗传多样性只有原位保存群体的71.1%，并且异位保存材料在聚类图中聚集在一起，仅为原位保护材料聚类图中的一个分支；虽然水桃树居群原、异位群体的遗传多样性指数分别为0.4100和0.4577,相差较小，并且原、异位保存材料在聚类图中混合聚类，似乎异位保存群体能够代表原居群的遗传多样性，但异位保存的14份材料在聚类图中有6份相邻的材料聚集在一起，说明异位保存取样时没有考虑野生稻植株的空间分布，属于重复取样，重复取样的比率高达42.9%。将2个分布点原、异位材料合并进行遗传多样性研究，结果与庵家山分布点的研究结果基本一致。据此推测我国保存的普通野生稻资源所包含的遗传变异相对较少，重复频率较高。建议进行普通野生稻遗传资源的再收集，并对已保存的野生稻种质资源进行全面鉴定，剔出重复样品。

Comparative Studies on Genetic Diversities Between In-situ and Ex-situ Conserved Germplasm of Oryza rufipogon

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.