Abstract

Percentage of grains with chalkiness (PGWC) is an important factor in determining the appearance quality of milled rice. A total of 10 main-effect quantitative trait loci QTLs were identified in four environments using 71 recombinant inbred lines (RILs) derived from a cross between Asominori (Japonica) and IR24 (Indica). These QTLs were further investigated using target chromosome segmental substitution lines (CSSLs) harboring them. The PGWC of the target CSSLs, harboring qPGWC-9,qPGWC-3 and qPGWC-5 alleles, was significantly different from Asominori (P < 0.05), indicating these three QTLs with relatively high stability. Importantly, PGWC of CSSL64 was significantly higher than that of Asominori in all the eight environments. We constructed an F₂ secondary population derived from Asominori × CSSL64 to explore the genetics of CSSL64 with high PGWC and qPGWC-9 was identified repeatedly in the three consecutive years (2005 to 2007). Further restriction in the interval of RM23958-RM1328 on chromosome 9, explained 19.3% of the phenotypic variance by its F₃ population. These results will be useful in fine-mapping and cloning of the qPGWC-9 allele and marker-assisted selection in rice high quality breeding programs.

Key words: Chromosome segmental substitution line (CSSL), recombinant inbred line (RIL), percentage of grains with chalkiness (PGWC), rice.