Molecular divergence and hybrid performance in rice
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Molecular divergence and hybrid performance in rice Zhang, Q., Y. J. Gao, M. A. Saghai Maroof, S. H. Yang and J. X. Li. 1995. Molecular Breeding 1:133-142. ABSTRACT This study was undertaken to determine the relationship between genetic distance of the parents based on molecular markers and F1 performance in a set of diallel crosses involving eight commonly used parental lines in hybrid rice production. The F1s and their parents were measured for five traits including heading date, plant height, straw weight, grain yield and biomass. The parental lines were assayed for morphisms (RFLPs) and 12 simpl sequence repeats (SSRs), resulting in a total of 105 polymorphic markers well spaced along the 12 rice chromosomes. SSRs detected more polymorphism than RFLPs among the eight lines. A cluster analysis based on marker genotypes separated these eight lines into three groups which agree essentially with the available pedigree information. Correlations were mostly low between general heterozygosity based on all the markers and F1 performance and heterosis. In contrast, very high correlations were detected between midparent heterosis and specific heterozygosity based on the markers that detected significant effects for all the five traits; these correlations may have practical utility in predicting heterosis. The analyses also suggest the existence of two likely heterotic groups in the rice germplasm represented by these eight lines. Key words genetic distance, heterosis, Oryza sativa, restriction fragment length polymorphism (RFLP), simple sequence repeat (SSR).