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Genetic diversity among venezuelan rice cultivars based on parentage coefficient estimation and analysis using microsatellite molecular markers (SSR)

Abstract:

Genetic relationships among 19 rice (Oryza sativa L.) varieties released in Venezueladuring the last 26 years were studied using pedigree and microsatellite molecular markers(SSR) analysis. Co-ancestry values among parents used in crosses that originated these cultivars varied between 0 and 24%, with an average of 9%. In turn, the coefficient of parentage between cultivar pairs ranged from 7.45% to 56.65%, with an average of 20.09%. Cluster analysis using the coefficient of parentage as a measure of similarity indicated that Venezuelan varieties can be grouped into eight distinctive sets. It was found that 29 out of 44 SSR markers were polymorphic, originating 84 polymorphic fragments. Alleles generated by each primer showed between 2 and 6 bands, with average of 3.1. Multiple correspondence analyses showed that three eigenvalues explained 59% of variance allowing grouping of the studied varieties in six discrete sets. It was observed that molecular analysis is more precise and informative than pedigree analysis; however, it does not distinguish between identity by descend or identity by state. Therefore, some genotypes could be grouped together even thought they do not have a common ancestor. These results show that Venezuelan rice varieties are related. Genetic diversity analysis yields highly similar groups, with He= 0.46958. Nonetheless, there are largely divergent materials and in consequence intercrossing and selection under local conditions could produce new cultivars with a higher yield potential, higher stability and better adaptability to the local growing conditions.