Genetic Diversity of Rice Landraces from Lowland and Upland Accessions of China

Genetic diversity of rice landraces from lowland and upland accessions of China was investigated using 66 polymorphic simple sequence repeat (SSR) markers. The total number of alleles detected from all 324 tested accessions was 555 with an average allele number (Na) of 8.409 per locus, the average effective number of alleles (Ne) of 3.574 and the average Shannon's information index (I) of 1.378. The genetic diversity was higher for the indica landraces compared to the japonica landraces, and the upland landraces were more genetically diverse than the lowland landraces. The SSR markers, RM72, RM232, RM219, RM241, RM224 and RM3 showed the highest rates of polymorphism and these SSR markers were suitable to assess the genetic diversity of rice germplasm resources. A dendrogram of 324 accessions of lowland and upland landraces showed that all rice accessions were mainly subdivided into two groups, japonica and indica, with some being intermediate. The distribution of lowland and upland landraces among the japonica and indica rice groups was distinct, with obvious differentiation between the lowland and upland landraces in japonica rice, but no such clear distinction in indica rice.