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 BC3F2 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 similar to 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.

Automated summary

Chalkiness in rice, a highly undesirable trait for breeding and marketing, is determined by the white-core rate (WCR) which was genetically validated and fine mapped in this study. The synthesis and accumulation of metabolites play a key role in chalkiness formation, with starch and storage protein being closely related to the white-core trait. These findings lay the foundation for map-based cloning of qWCR7, which may have potential value in quality improvement during rice breeding.