理想株型是水稻高产稳产的关键，株高是理想株型的重要农艺性状，挖掘并有效利用株高基因对完善株型分子调控机制和水稻育种具有重要意义。作为前期基础，本项目组以Kitaake组培后代突变体sgd2为研究材料，通过正向遗传学的方法图位克隆并功能验证了株型新基因SGD2，其功能注释为HD-ZipII类转录因子家族成员HOX3。细胞学实验表明SGD2通过影响细胞生长发育来调控水稻株高和粒型，进一步研究发现SGD2是一个组成型表达基因，主要在未开花的幼穗中表达，亚细胞定位于细胞核。激素处理实验发现，突变体sgd2能够响应外源GA，预示着sgd2的GA信号途径正常，GA合成途径受阻是导致sgd2发生突变的主要因素。本项目拟进一步通过对转录因子SGD2进行深入的功能研究，揭示该基因在水稻GA合成代谢途径中的作用，全面解析SGD2的分子调控机制，阐明SGD2参与的水稻株型遗传网络模型。

Ideal plant architecture is the key to high and stable yield of rice, plant height is an important agronomic character of ideal plant architecture. Previously we have cloned and functionally verified the novel gene SGD2 by the method of forward genetics with the mutant sgd2 from Kitaake. SGD2 was functional annotated as HOX3, a member of the HD-Zip II family transcription factor. Cytological experiments showed that SGD2 regulated rice plant height and grain size by affecting cell growth and development. Further studies showed that SGD2 was a constitutive expression gene, which was mainly expressed in young panicles before flowering, and its subcellular location was in the nucleus. Hormone treatment experiments showed that the mutant sgd2 could respond to exogenous GA, indicating that the GA signal pathway of sgd2 was normal, and the blocked GA synthesis pathway was the main factor leading to the mutation of sgd2. This project intends to further investigate the function of transcription factor SGD2, reveal the role of this gene in the GA biosynthetic pathway of rice, comprehensively analyze the molecular regulation mechanism of SGD2, and clarify the genetic network model of rice plant architecture in which SGD2 is involved.