Comparative Studies on Intra-varietal Heterogeneity between Rice Landraces and Improved Varieties

Yunnan province is the Asian cultivated rice primary and diversity center , some rice landraces have been planted continuously for a long term. These landraces are all important research samples for effective conservation and sustainable development of crop germplasm resources. In this study, twenty-four pairs of SSR markers were used to compare the intra-varietal heterogeneity among 3 rice landraces that have been planted in Yuanyang with a long history and 3 improved varieties that have been eliminated in Yuanyang. A total of 103 SSR alleles have been found. The alleles revealed in rice landraces are much more than that in improved varieties and some SSR alleles have disappeared in improved varieties. The results showed that the intra-varietal heterogeneity in rice landraces is richer than that in improved varieties; therefore, rice landraces have high adaptability with lighter selective pressures.