垩白是影响稻米品质的最重要因素，垩白米严重影响稻米加工品质和蒸煮食味品质。研究表明，稻米垩白是多基因控制的数量性状，其调控的分子机理仍不清楚。本项目以低垩白品种Lemont为供体亲本、高垩白品种特青为受体亲本构建染色体片段代换系（CSSLs），并在第6染色体长臂末端检测到一个影响稻米垩白度的主效QTL（qCD-6），目前已将该QTL定位于Indel1和RM2744间约625Kb的区间，获得了携带QTL qCD-6的低垩白度代换系BIL16。本研究拟选择携带垩白度QTL qCD-6染色体代换系与特青回交构建次级分离群体，精细定位目标基因；整合染色体代换系、基因定位结果和生物信息学的方法进行基因候选；克隆垩白度qCD-6基因，鉴定其生物学功能；利用RT-PCR技术分析基因表达特征。研究结果将对阐明稻米垩白调控的分子机理，提供新的基因用于低垩白水稻分子育种，培育优质水稻品种具有重要意义。

Chalkiness is one of the most important quality traits of rice, which is directly related to the value of rice and rice grain quality composition. It is one of the major limiting factor of good quality rice breeding. Chalkiness is a typical quantitative trait, the genetic mechanism is relatively complex, its regulation molecular mechanism remains unclear. The Isogenic Introgression Lines (ILs) in the Teqing background with introgressed Lemont segments were analyzed, the QTL (qCD-6) was detected in the end of the long arm of chromosome 6, and the QTL qCD-6 which were detected in the Isogenic Introgression Lines BIL16 with low chalkiness degree. In this study, the cross BIL16 × Teqing was used to build sub-backcross segregating populations and fine mapping chalkiness gene qCD-6. The qCD-6 gene will be found and cloned by using the results of gene mapping and bioinformatics approach. We also will identify its biological function and molecule regulatory pathways involved in the chalkiness degree of rice. The results will not only clarify the molecular mechanism of the regulation of chalky rice, but also provide new genes for molecular breeding in rice.