Genetic basis of low-temperature-sensitive sterility in indica-japonica hybrids of rice as ...
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Genetic basis of low-temperature-sensitive sterility in indica-japonica hybrids of rice as determined by RFLP analysis Li, H. B., J. Wang, A. M. Liu, K. D. Liu, Q. Zhang, J. S. Zou. 1997. Theor. Appl. Genet. 95:1092-1097. ABSTRACT Low-temperature-sensitive sterility (LTSS) has become one of the major obstacles in indica-japonica hybrid rice breeding. In this study, we determined, using RFLP markers, the genetic basis of LTSS in two populations from crosses between an indica and japonica parents, the BC1F1 of 3037/02428//3037 and the F2 of 3037/02428. The fertility segregation in the two populations under low-temperature conditions was used as a measurement for temperature sensitivity of the various genotypes in the populations. RFLP survey of bulked extremes from the BC1F1 population identified three genomic regions, 2 on chromosome 1 and one on chromosome 12, that were likely to contain genes for LTSS (or Ste loci). One-way ANOVA and QTL analysis using a total of 19 markers from these three genomic regions resolved three Ste loci in the BC1F1 population and two Ste loci in the F2 population. These loci were distinct from those governing wide-compatibility identified in previous studies, according to the chromosomal locations. Two- and three-way ANOVA showed that these loci acted essentially independent of each other in conditioning LTSS. The main mode of gene action was an interaction between the indica and the japonica alleles within each locus resulting in a drastic fertility reduction in the heterozygote relative to the homozygotes of the respective locus. The results have significant implications in indica-japonica hybrid rice breeding programs. Key words Oryza sativa, hybrid sterility, Ste loci, molecular markers, hybrid rice breeding