The genetic structure of Chinese rice cultivars was analyzed according to allozyme variation by starch gel electrophoresis. Twelve polymorphic loci coding for 5 allozymes were surveyed among 6330 Chinese rice cultivars including 5492 traditional rice and 838 inbred varieties. Fiftythree alleles were detected with a genetic diversity index of 0.269. The difference in diversity index was not significant between traditional and inbred rice. But total allele number of traditional rice was higher than that of modern inbred varieties. Comparing the allozyme diversity among six rice ecoregions of China, it is found that the diversity center of allozyme is in southwest ecoregion of China, while most rear alleles existing in the rice cultivation regions of North China and East China. This finding indicates that the north and east rice cultivation regions are probably related with the origin of rice in China. The traditional cultivars were clustered into two major groups, indica and japonica. The diversity of indica was higher than that of japonica. The pronounced nonrandom associations among alleles at many unlinked enzyme loci as well as the significant differences of frequencies at individual locus indicate the significant difference between the subspecies of rice, indica and japonica.
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