Study of Allelic Frequency and Polymorphism of Isozyme Markers in Iranian Rice

Isozymes are useful and important markers for studying genetic structure and breeding of rice. The level of polymorphism is an important character of each marker that represents its validation and relative importance. Allelic frequencies represent genetic structure of populations. Therefore, this investigation was conducted for evaluation of genetic structure and identifying of relative importance of isozyme loci in Iranian landraces of rice. One hundred twenty rice accessions were selected from National Plant Gene Bank of Iran (NPGBI). In each sample, enzyme extract was extracted from 4-6 seedlings. Separation and visualization of isozymes was carried out using Glaszman et al. (1988) protocol, with some minor modifications. In most isozymic loci, allelic frequencies of Iranian landraces had significant differences with average of other Asian rices. Also in each locus, one or two alleles were frequent. Five loci including Amp3, Pgi2, Est2, Amp1 and Amp2 with 60, 55.3, 54.8, 51 and 48 percent were more polymorphic, respectively. Three loci, Amp4, Est5 and Est9 were monomorphic and they are not useful markers for rice. Genetic diversity of Iranian landraces and Asian rices on Cat1, Pgi2, Amp3, Amp4 and Est5 loci have not significant diffrences, however, Pgi1, Est9, Est1 and Amp1 were reverse. Genotypic diversity index was 3.46, which is high in comparison with other Asian rices. These results showed a very high genetic variability and special genetic structure in Iranian landraces of rice. These can be due mainly to independent evolution of Iranian land races in unique ecological region of Iran which differes with the ecological conditions in the origin of rice in Southeast of Asia, India and China.