淀粉积累是花粉成熟的主要标志并且提供花粉管萌发和生长所需的能量，其积累缺陷会显著影响花粉活力。由于淀粉积累是花粉成熟的关键节点，因而对其调控机制的研究有重要意义。GRAS家族蛋白作为GA信号通路中的关键转录因子广泛参与植物生长发育调控，但对其在花粉淀粉积累中的功能仍未见报导。本项目前期发现GRAS家族蛋白ZmSCL1参与花粉淀粉蓄积调控，该基因主要在花粉中特异表达，其Ac/Ds突变体和RNAi株系花粉的淀粉积累均减弱。此外，ZmSCL1定位于细胞核且不具有转录激活活性，提示其可能通过蛋白互作调控下游基因表达。因此，本项目拟探明突变体中花粉淀粉积累受阻的成因及其对花粉活力的影响。通过筛选ZmSCL1互作蛋白和解析其下游基因表达调控网络，阐明ZmSCL1在花粉淀粉积累过程中的作用和调控机制。本研究对于解释GA信号在淀粉代谢中的作用具有重要意义，同时还可为玉米雄性不育调控提供新机制和基因资源。

The process of starch accumulation is a sign of pollen maturation, and it provides energy for the germination and growth of pollen tubes. The defects of starch accumulation may lead to a significant reduction of pollen vitality. Since, starch accumulation is a critical check point of pollen maturation, identifying the molecular mechanism regulating starch accumulation in pollen is of great theoretical significance. The GRAS family proteins are important transcriptional regulators in GA signal transduction and have diverse functions in plant growth, though the understanding of their roles in regulating starch accumulation in pollen grains is limited. Our previous study showed that ZmSCL1 expressed predominantly in pollen grains. Both ZmSCL1 Ac/Ds insertion mutant and its RNAi transgenic lines exhibited a reduced starch accumulation phenotype, suggesting that ZmSCL1 is critical for the starch metabolism in pollen. Besides, ZmSCL1 is localized in the nucleus, though it does not have transcription activation ability. This result indicates that ZmSCL1 may regulate downstream gene expressions by interacting with other transcription factors. In this proposal, we will investigate the physiological cause of pollen starch accumulation defects in the mutants and RNAi lines, and evaluate whether the pollen vitality was reduced. Moreover, we plan to screen interacting proteins of ZmSCL1 and identify its downstream genes. The prospective result of this research may provide molecular mechanism by which ZmSCL1 regulates starch accumulation in pollen, and explain the roles of GA signaling in pollen starch metabolism. In addition, our study may also provide putative approaches and gene resources for generating male-sterile lines of maize.