Molecular marker heterozygosity and heterotic performance in Philippine rice hybrids
1999
Moreno, L.S. | Ordonez, S.A. Jr. | Redona, E.D. (Philippine Rice Research Inst., Maligaya, Munoz, Nueva Ecija 3119 (Philippines))
The magnitude of heterosis in F1 hybrids have been acknowledge to be associated with genetic diversity. Simple sequence repeats (SSR's) or microsatellites are among the DNA marker types effective in assessing diversity at the DNA level. In this study, the relationship of SSR heterozygosity and heterotic potential fo eight vegetative and reproductive traits in 48 rice hybrids derived from 5 cytoplasmic-genetic male sterile (CMS) and 10 male parents was examined. These parental lines represented the breadth of genetic diversity in current Philippine hybrid rice germplasm. F1 heterozygosity was deduced from parental genotypes at 44 microsatellite loci spanning the 12 rice chromosomes. Based on at least 75 percent genetic similarity, the CMS and male parents clustered into 2 and 8 groups, respectively. SSR heterozygosity and heterotic performance (superiority over the male parents) in the 48 hybrids were significantly correlated for the number of productive tillers per plant (r=0.37] and leaf area index (r=0.34]. When only hybrids with positive heterosis were analyzed to remove maintainer effects, marker heterozygosity and heterosis were significantly correlated for maturity (r=0.60], leaf area index (r=0.45*], and number of productive tillers per plant (r=0.43*]. However, insignificant correlations were observed for plant height, root length, root weight, harvest index, and grain yield. Correlations were also insignificant when heterosis was based on the check varieties, PSBRc28 and PSBRc 72H (Mestizo). These results suggest that while SSTs are useful for genetic diversity assessment, markers unlinked to specific traits may not be very effective in predicting heterostic performance for these traits in the diverse hybrid rice germplasm pool studied
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