[Analysis of genetic variation in rice paddy landraces across 30 years as revealed by microsatellite DNA markers].

To reveal the genetic variation of rice paddy landraces across 30 years, we compared the genetic variation of between 6 paddy rice landraces grown in Yuanyang Hani's terraced fields in Yuanyang County, Yunnan Province in the 1970s (past-grown landraces) and 6 paired ones that have been grown during the past decade (current-grown landraces) using 60 SSR markers. The results showed that one to four alleles were amplified in 60 loci and 159 alleles in all the landraces tested. The number of alleles from the current-grown landraces decreased by 7 alleles compared to the past-grown landraces. The average number of alleles (Na), effective number of alleles (Ne), locus polymorphism information content (PIC), and genotype diversity (H') of the past-grown landraces were higher than those of the current-grown landraces, with Na of 2.567>2.450, Ne of 2.052>1.968, PIC of 0.469>0.439, and H' of 0.768>0.722. The average genetic similarity coefficient (GS) of the past-grown landraces was 0.437 with a range from 0.200 to 0.700 based on the 60 SSR markers, and the average GS of the current-grown landraces was 0.473 with a range from 0.117 to 0.667. In conclusion, the genetic diversity in current-grown landraces was decreased compared to the past-grown landraces, and the degree of variation in some of the allele locus varied in different rice landraces as a result of 30 years' natural and artificial selection.