Validation and Fine Mapping a Multifunction Region qPCG10 / qDC10 Conferring Chalkiness and Grain Shape of Rice

Chalkiness and grain shape are two important appearance traits of milled rice (Oryza sativa L.), and grain shape is generally considered to greatly affect chalkiness of endosperm. This study was conducted to validate and fine map an important multifunction region located on the long arm of rice chromosome 10, qPCG10/qDC10, conferring grain shape and chalkiness that has not been well characterized. The quantitative trait loci validations were first performed using BC₂F₂ and BC₂F₂:₃ populations derived from indica maternal line Teqing and recurrent paternal line IR24. Plants with overlapping heterozygous segments in the interval of RM3773 to RM6673 were selected from the BC₄F₂ population to develop near-isogenic lines for fine mapping of qPCG10/qDC10. Using two-way ANOVA of phenotypic variance among three genotype groups in each near-isogenic line set, qPCG10/qDC10 was delimited to a 93.4-kb region flanked by RM25828 and RM3123 and showed significant effects on grain width, grain length, 1000-grain weight, percentage of chalky grain, and degree of chalkiness. We speculated that the multifunction region may harbor a novel gene causing chalkiness and grain shape. The present study will facilitate the cloning of qPCG10/qDC10 and the exploration of the molecular mechanisms underlying rice grain chalkiness.