株高和粒型是水稻重要的农艺性状，阐明其调控机理是进一步提高水稻产量的基础。前期工作中从TP309中获得了一个小粒矮秆突变体sgd2，遗传分析表明该突变是由单隐性核基因控制的。通过图位克隆获得控制株高和粒型的基因SGD2，并通过遗传互补和CRISPR/Cas9敲除实验证实该基因。此外，还发现SGD2可能参与调控GA生物合成和BR信号传导。本研究以sgd2突变体和TP309为材料，利用扫描电镜观察了解株高变矮和籽粒变小的原因。利用GUS组织化学染色和qRT-PCR分析SGD2时空表达模式。测定内源GA和BR含量，结合转录组测序和qRT-PCR分析明确激素相关差异表达基因。对SGD2进行亚细胞定位，并通过酵母双杂交、pull-down和BiFC实验明确SGD2互作蛋白。本项目将阐明SGD2参与调控激素相关基因控制株高和粒型的分子机理，有助于水稻高产育种。

Plant height and grain size are important agronomic traits of rice. To elucidate their regulation mechanism is the basis for further improving rice yield. A small grain dwarf mutant sgd2 was obtained from TP309 in previous work. Genetic analysis showed that the mutation was controlled by a single recessive nuclear gene. SGD2, a gene controlling plant height and grain size, was obtained by map-based cloning and confirmed by genetic complementation and CRISPR/Cas9 knockout experiments. In addition, SGD2 may be involved in regulating GA biosynthesis and BR signal transduction. In this study, the sgd2 mutant and TP309 are used as materials to understand the causes of plant height dwarfing and grain dwarfing by scanning electron microscopy observation. Spatiotemporal expression pattern of SGD2 is analyzed by GUS histochemical staining and qRT-PCR. Endogenous GA and BR contents are determined, and hormone-related differentially expressed genes are identified by transcriptome sequencing and qRT-PCR analysis. Subcellular localization of SGD2 is carried out, and SGD2 interacting proteins are identified by yeast two-hybrid, pull-down and BiFC experiments. This project will elucidate the molecular mechanism of SGD2 involved in regulating hormone-related genes to control plant height and grain size, and contribute to rice high-yield breeding.