QTL Analysis For Chalkiness Of Rice And Fine Mapping Of QACE9

Chalkiness is one of the most important appearance quality indicators, particularly for the nutritional value and economic value of the rice varieties. As an important quality traits, chalkiness is also an important standard of rice quality classification, and there are significant correlation between rice chalkiness and other rice quality characters. The formation of rice chalkiness of the complicated physiological process is synergistic effected by the related biosynthesis and accumulation of starch, dynamics of grain filing and relation between "sink-source". Rice chalkiness is a complicated quantitative trait, which is controlled by genetic factor, but the external environment factors also has important influence. There are many genes controlling rice chalkiness, which have an impact on starch synthesis, sterility and grain size, have been cloned. Both in domestic and foreign, the research of QTL mapping have made important progress, which have important values in the future rice quality improvement.In this study, using recombinant inbred lines (RELs) of PA64s and 9311, we identified 19 QTLs on chromosomes 1,4,6,7,9 and 12, which accounted for 5.1% to 30.6% of the phenotypic variations. A novel major QTL qACE9 for the area of chalky endosperm (ACE) was detected in Hainan and Hangzhou, and both mapped in the overlapping region on chromosome 9. It was further fine mapped to an interval of 22 kb between two insertion-deletion (InDel) markers IND9-4 and IND9-5 using a BC4F2 population. Gene prediction analysis identified five putative genes, among which only one gene (OsAPS1), whose product responsible for starch synthesis, was detected two nucleotide substitutions causing amino acid change between the parents. Therefore, OsAPS1 was selected as a novel candidate gene for qACE9.