Genetic erosion in northern marginal population of the common wild rice Oryza rufipogon Griff, and its conservation, revealed by the change of population genetic structure

In order to monitor genetic erosion within the northern marginal population of common wild rice Oryza rufipogon Griff. from Dongxiang, Jiangxi Province. China. allozyme diversity encoded by 22 loci was analyzed electrophoretically from all the existing subpopulations in 1980. 1985 and 1994. The sample collected from the nine large subpopulations in 1980 showed the highest levels of genetic diversity (A = 1.27, P = 18.20 %. Ho = 0.042 and He = 0.049) and a slight deviation From Hardy-Weinberg expectation (F = 0.143), the sample from five moderate ones in 1985 displayed medium levels of genetic diversity (A = 1.14, P = 13.60%, Ho = 0.008 and He = 0.049) and a great deviation from Hardy-Weinberg expectation (F = 0.837). and the sample from two small ones in 1994 demonstrated the lowest levels of genetic diversity (A = 1.09. P = 9.10%. Ho = 0.000 and He = 0.043) and the largest deviation from Hardy-Weinberg expectation (F= 1.000). The results not only documented the genetic erosion stemmed from the extinction of the subpopulations, but also revealed the drastic change of the population genetic structure due to the reduction of the population. Finally. some conservation strategies for the population are proposed.