水稻粒型与产量和品质密切相关，相关基因的鉴定和分子机制研究可为水稻产量和品质的改良提供遗传信息。在前期研究中，项目组从以籼稻广陆矮4号为受体、粳稻日本晴为供体的染色体片段代换系中鉴定了一个新的水稻细长粒型QTL位点LNG7，来源于日本晴的等位基因可增加粒长，减小粒宽，导致长宽比增加，形成细长粒型，但对粒重没有影响；同时降低垩白度，改良稻米外观品质。通过图位克隆，将其精细定位于第7染色体上35Kb的物理区间，并初步确定了一个候选基因。本项目拟通过互补试验确定LNG7的目标基因；综合利用农艺学、分子遗传学和功能基因组学技术手段，阐明LNG7调控细长粒型的生物学功能；利用转录组学和蛋白互作分析构建LNG7参与细长粒型调控的遗传网络；通过构建近等基因系，双突、多突突变体，阐明LNG7与其它粒型基因的互作效应，明确它们对产量和稻米品质的影响，评价其育种价值。最终为水稻品质改良提供重要遗传信息。

Rice is one of the most important crops in China. Grain shape is closely related to grain yield and quality in rice. Identification and mechanism of the genes responsible for grain shape provides genetic information to improve rice grain yield and quality. Previously, we identified a novel QTL, LNG7 (Long and narrow grain on chromosome 7), regulating grain shape, using chromosome segment substitution lines derived from a japonica cultivar, Nipponbare, as the donor, and an indica cultivar, Guangluai 4, as the receptor. The Nipponbare LNG7 allele increased grain length and reduced grain width, but it had no effect on grain weight. As a result, the introgression line carrying Nipponbare LNG7 allele produced longer and narrower grains. In addition, the chalkiness degree was obviously decreased and appearance quality was improved. LNG7 was fine-mapped into a 35Kb segment on chromosome 7, and one putative gene in this region was considered as the candidate. . In this project, we will use complementary test to confirm the target gene of LNG7. Agronomic, molecular and genomic technologies will be employed to investigate the biological function of LNG7. The genetic networks of LNG7 in regulating slender grains will be uncovered through transcriptomics and protein-protein interaction analyses. We will develop a set of genetic materials, including near iso-genic lines and multiple mutants, to reveal the interaction effects between LNG7 and other grain shape related genes. The breeding value of LNG7 will be investigated after estimating the effects of LNG7 on grain yield and quality. Our results will provide important information for the improvement of rice appearance quality.