Abstract: The genetic similarity of 313 japonica developing varieties from 17 countries and 2 international organizations was analyzed using SSR markers. With 34 SSR primers which were polymorphic and uniformly distributed in rice genome, total 198 alleles were detected among these developing varieties with the average number of alleles per pair of primers was 5.8235. RM320, RM531, RM1, RM21 and RM336 possessed more alleles, which were 16, 13, 12, 10 and 10 respectively. RM320, RM336, RM286, RM531 and RM21 showed higher genetic diversity indexes, which were 2.3668, 2.0041, 1.9684, 1.9508 and 1.7203 respectively. The latitudes of Korea, Democratic People’s Republic of Korea, Japan, Russia, China, America, Hungary, Bulgaria, France, Italy and Turkey (group I) were higher than 30ºN, in which the genetic similarity coefficients of japonica developing varieties ranged from 0.697 to 0.918 with the average of 0.797. The latitudes of Nepal, Egypt, Mexico and Senegal (group II) were between 15ºN and 30ºN, in which the genetic similarity coefficients of japonica developing varieties ranged from 0.381 to 0.618 with the average of 0.503. The latitudes of Brazil, West Africa Rice Center(WARDA), International Center for Tropical Agriculture(CIAT) and Chile (group III) were lower than 15ºN, in which the genetic similarity coefficients of japonica developing varieties ranged from 0.649 to 0.757 with the average of 0.701. The genetic similarity coefficients of japonica developing varieties among different countries or organizations of different groups were smaller than them among different countries or organizations of the same group on the whole. The rice varieties from higher latitude countries were clustered together, while the rice varieties from lower latitude countries or organizations were clustered together. The results indicated the genetic similarities among japonica developing varieties had a close relationship with the geographical position, especially with the latitude of these japonica developing varieties.

Key words: 粳稻, 遗传相似性, 地理来源, 纬度, 微卫星标记