水稻DZ1及其抑制子基因SOD1调控籽粒大小的分子遗传网络解析

水稻籽粒大小是重要的产量性状，但籽粒大小调控的分子遗传网络目前仍不清楚。申请人实验室已系统分离了水稻籽粒大小改变的突变体。其中，dz1-1突变体产生较大的种子。DZ1基因编码了一个未知功能的转录因子。我们进一步分离了dz1-1的抑制子突变体sod1，SOD1编码了一个预测的转录调控因子。遗传分析表明DZ1和SOD1作用在同一遗传途径。DZ1能够与SOD1在细胞核内互作作用。本项目拟从以下三个方面，解析DZ1和SOD1调控籽粒大小的分子遗传网络。1、解析DZ1和SOD1调控籽粒大小的细胞学和发育生物学基础及其生化活性。2、鉴定DZ1结合的顺式元件，DZ1和SOD1调控的靶基因，建立DZ1和SOD1调控籽粒大小的转录网络。3、鉴定DZ1和SOD1复合体的其他成员，解析DZ1和SOD1互作调控籽粒大小的新机制。该研究有望在水稻籽粒大小调控领域取得重要突破，也将为高产育种提供理论基础和基因资源。

Rice grain size is an important agronomic trait, and control of grain size is also a fundamental question in developmental biology. However, the genetic and molecular mechanisms that set final grain size are largely unknown despite their central importance. To understand the genetic and molecular mechanisms of grain size control, we have isolated a set of mutants with altered grain size in rice and identified numerous genes of grain size control. The dz1-1 mutant shows large grains compared with the wild type. DZ1 encodes a putative transcription factor with unknown functions. To understand the genetic and molecular mechanisms of DZ1 in grain size control, we have isolated the suppressors of dz1-1 (sod). Genetic analyses show that sod1-1 is epistatic to dz1-1 with respect to grain size, indicating that DZ1 and SOD1 act in a common pathway to control grain size. SOD1 encodes a predicted regulator of transcriptional regulation. Further results show that DZ1 interacts with SOD1 in the nuclei. These findings provide an opportunity to reveal novel mechanisms of grain size control in rice. The three major objectives of this project are: 1, To investigate developmental and cellular basis and biochemical activities of DZ1 and SOD1. 2, To identify the binding sites (cis-elements) of DZ1 in genome and build up a transcriptional network for DZ1 and SOD1-mediated grain size control. 3, To identify other components of the DZ1/SOD1 complex and elucidate the molecular mechanisms of DZ1 and SOD1 in grain size control. This study will make a breakthrough in rice grain size control and discover important genes for engineering high crop yield.