Genetic analysis of rice grain quality

The inheritance of grain quality is more complicated than that of other agr onomic traits in cereals due to epistasis, maternal and cytoplasmic effects . and the triploid nature of endosperm. In the present study, an establishe d rice DH population derived from anther culture of an indica/japonica hybr id was used for genetic analysis of rice grain quality. A total of five par ameters, amylose content (AC), alkali-spreading score (ASS), gel consistenc y (GC), percentage of grain with a white core (PGWC) and the square of the white core (SWC), were estimated for the DH lines and the parent varieties. For each parent, the value of each parameter was relatively stable in thre e locations, Beijing, Hangzhou and Chengdu, while the differences between t he parents were significant for all five parameters. AC showed a bimodal di stribution, and the distribution of ASS was skewed toward the value of JX17 , while the other three parameters displayed continuous distributions among the DH lines with partially transgressive segregations. For AC, a minor an d a major gene were found on chromosomes 5 and 6 respectively. The major ge ne, which should be an allele of wx, explained 91.9% of the total variation . For GC, two QTLs were identified on chromosomes 2 and 7 respectively. For ASS, a minor and a major gene were both located on chromosome 6. The major gene should be the same locus as the alkali degeneration gene talk). Genet ic linkage between alk and wx was found in QTL mapping. For PGWC, two QTLs were located on chromosomes 8 and 12. Only a minor QTL was found for SWC on chromosome 3. The results and the molecular markers presented here may be useful in rice breeding for grain quality improvement.