淀粉是水稻种子中最主要的成分，其结构、理化性质是稻米品质的决定性因素。因此，研究淀粉生物合成过程的分子机制对高产优质育种具有重要指导意义。我们筛选到一个严重腹白、总淀粉含量及千粒重显著降低的突变体oswb1。图位克隆发现OsWB1基因第一外显子发生了一个单碱基替换，导致蛋白翻译提前终止。遗传互补表明该基因能使突变体表型恢复正常。OsWB1在胚乳中特异表达，与已报道的相关基因不等位，转录激活实验证明OsWB1具有转录激活活性，推测OsWB1是一个新的调控水稻胚乳淀粉合成及稻米品质的转录因子。本研究旨在进一步验证OsWB1生物学功能；明确OsWB1的时空表达特性和亚细胞定位；鉴定其互作蛋白；明确其调控的下游靶基因，初步阐明OsWB1对水稻胚乳淀粉合成及稻米品质的调控机理；并对该基因开展单倍体型分析，发掘有利于提高水稻产量与品质的有利等位基因。为培育高产、低垩白水稻品种提供理论基础与基因资源。

Rice grain quality is largely determined by the structure and chemical and physical properties of starch, which is the most abundant composition of rice grains. Elucidating the molecular mechanism of starch biosynthesis is certainly useful for high yield and good quality breeding practice. This proposal aims to clone and functionally characterize a novel gene deriving from a mutant oswb1 with severe chalkiness, decreased starch content and reduced grain weights. Our previous efforts have fine mapped the OsWB1 on Chr.10. A single-base substitution in the 2nd exon caused premature termination of the resulting protein in oswb1. Functional complementarity experiment further proved that OsWB1 was responsible for the phenotypes of oswb1. OsWB1 is specifically transcribed in developing seeds. To the best of our knowledge, OsWB1 is novel gene whose biological function remains untouched so far. Transcriptional activation experiment revealed that OsWB1 had transcriptional activation activity, suggesting that it may work as a transcription factor. In this proposed study, the physicochemical properties will be compared between oswb1 and the wild type to further determine its biological function. The expression profile and subcellular localization of OsWB1 will be analyzed. The interactive protein and direct target genes of OsWB1 will also be investigated to elucidate the underlying mechanism of OsWB1-regulated starch biosynthesis. Furthermore, the genotype or haplotype analysis will be carried out to find applicable alleles for rice yield and quality improvement. The outcome of this project is expected to provide a theoretical basis and genetic resources for the breeding of rice varieties with high-yield and low chalkiness.