Abstract:

To estimate QTL for the pollen sterility, an F₂ population of 180 plants from an indica / japonica hybrid was tested with 110 molecular markers. By the genome wide screening, three QTLs were identified for the pollen sterility on chromosomes 3, 5, 7, respectively. In addition, a total of nine QTL for segregation distortion via male gametes were mapped on rice chromosomes, of which seven QTLs were suggested to be the same type of gamete abortion as found at ga-14 and ga-11. The distortion data seemed to be more sensitive to detection of pollen abortion genes in the F₁ hybrid than the morphological inspection of pollen. Two QTLs for the segregation distortion on chromosomes 5 and 6 indicated an abnormally high frequency of heterozygous genotype. At a locus indicated by qHPS-5, japonica-type homozygote showed a lower fertility level than the heterozygotes and indica-type homozygote. The molecular markers identified here would be useful in introducing a set of new and known sterility-neutral alleles to solve the pollen sterility problem in subspecific F₁ hybrids. Further, the present results could be helpful to combine as many neutral alleles for distortion as possible on whole genome basis to stabilize the pollen fertility as a whole.

Key words: Rice (Oryza sativa L.), Quantitative trait loci (QTL), Molecular marker, Pollen sterility, Hybrid sterility