Mapping quantitative trait loci for milling quality, protein content and color characteristics of rice using a recombinant inbred line population derived from an elite rice hybrid

Milling properties, protein content, and flour color are important factors in rice. A marker-based genetic analysis of these traits was carried out in this study using recombinant inbred lines (RILs) derived from an elite hybrid cross 'Shanyou 63', the most-widely grown rice hybrid in production in China. Correlation analysis shows that the traits were inter-correlated, though the coefficients were generally small. Quantitative trait locus (QTL) analysis with both interval mapping (IM) and composite interval mapping (CIM) revealed that the milling properties were controlled by the same few loci that are responsible for grain shape. The QTL located in the interval of RM42-C734b was the major locus for brown rice yield, and the QTL located in the interval of C1087-RZ403 was the major locus for head rice yield. These two QTLs are the loci for grain width and length, respectively. The Wx gene plays a major role in determining protein content and flour color, and is modified by several QTLs with minor effect. The implications of the results in rice breeding were discussed.