Comparative assessment of SSR diversity in aromatic rice germplasm

The genetic diversity in 370 aromatic rice germplasms introduced from home and abroad, was investigated by using a total of 60 SSR markers. 361 alleles were detected, with the number of alleles (Na) per loci ranging from 2 to 10. The Nei's genetic diversity index (He) among loci varied widely from 0.104 at RM308 to 0.885 at RM2634 with an average value of 0.663. There was an obvious difference in SSR allelic diversity between indica and japonica rice. Indica rice showed more variation than japonica rice both for Na and He. Meanwhile, the genetic diversity of the landraces was higher than that of the improved varieties, and Na of the improved varieties was 86.5% of the landraces. Analysis of molecular variance indicated that 43.08% of the variation was from genetic differences between subspecies. It was also demonstrated that the genetic differentiation among different rice ecological regions ranged from 1.69% to 14.40%. There was significant differentiation between Southern China and Southwestern China, Central China and Southwestern China, respectively. Cluster analysis showed that 370 aromatic rice varieties were mainly classified into indica and japonica, and aromatic rice varieties from the same areas or the neighboring provinces were basically assigned to the same group.