Fine mapping of qWCR7 , a grain chalkiness QTL in rice

Chalkiness is one of the key determinants of rice quality and is a highly undesirable trait for breeding and marketing. In this study, qWCR7 , a major quantitative trait locus (QTL) of white-core rate (WCR), was genetically validated using a BC 3 F 2 segregation population and further fine mapped using a near isogenic line (NIL) population, of which both were derived from a cross between the donor parent DL208 and the recurrent parent ZS97. qWCR7 was finally narrowed to a genomic interval of ~ 68 kb, containing seven annotated genes. Among those, two genes displayed markedly different expression levels in endosperm of NILs. Transcriptome analysis showed that the synthesis and accumulation of metabolites played a key role in chalkiness formation. The contents of storage components and expression levels of related genes were detected, suggesting that starch and storage protein were closely related to white-core trait. Our findings have laid the foundation of map-based cloning of qWCR7 , which may have potential value in quality improvement during rice breeding.