The genetic differentiation of dongxiang wild rice (Oryza rufipogon Griff.) and its implications for In-Situ conservation

Chinese. 东乡野生稻是世界上分布最北的普通野生稻居群，研究其遗传分化不仅能够阐明居群的起源、演化规律，而且可为其保护提供理论依据。利用SSR（简单序列重复）分子标记对江西东乡普通野生稻仅存的2个原位保护居群进行了30个位点的遗传多样性分析和遗传分化研究。东乡野生稻2个居群内和居群间的遗传多样性指数分别为0.4120和0.0564，居群间遗传分化系数仅为0.1219，即87%以上的遗传变异存在于居群内。POPGENE聚类分析结果也显示，东乡野生稻的2个居群实际属于一个大群体，水桃树居群可看作庵家山居群的一个分支。利用同样方法对庵家山居群人为隔离的3个小群体进行的研究结果表明，虽然3个小群体间遗传分化系数也很低（0.0975），仍然属于同一居群，但人工隔离引起的小生境变化已使得3个群体发生了遗传分化。在建立东乡野生稻原生境保护点时，一方面，应以有效保护庵家山居群为重点，另一方面，对庵家山居群的保护应充分考虑原居群的生态环境，拆除原有围墙，进行生态恢复。

English. Dongxiang wild rice (Oryza rufipogon Griff.) distributes at 28°14′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. Studies on the genetic differentiation could not only reveal the principle of origination and evolution of the populations, but also provide theoretical evidence of their conservation. To analyze the genetic differentiation of the populations, 30 pairs of SSR 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, three 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 three sub-populations. 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.