灌浆效率低、产量不稳定是现在超级稻生产面临的主要问题之一，研究表明在水稻灌浆期适度干旱可促进非结构性碳水化合物（NSC）的再利用并提高水稻弱势粒的灌浆效率，然而，我们至今对适度干旱以及这两个生物过程的关系及调控分子机理仍不甚了解。针对这一问题，本项目拟利用多种组学方法及关联分析方法全局性、系统性地研究超级稻和常规稻茎鞘中所有基因和蛋白的表达量及DNA甲基化对它们的调控机理，后续将利用反向遗传学技术验证组学结果中的关键基因，并用生理生化和分子生物学技术检测茎鞘及强弱势粒中NSC和淀粉代谢相关酶活性及植物激素等干旱相关代谢产物的含量变化。通过以上实验我们希望能够揭示适度干旱调控NSC再利用和弱势粒灌浆的分子机理，构建超级稻中茎鞘NSC再利用和弱势粒灌浆的调控网络。本项目成果不仅对揭示水稻弱势粒种子灌浆规律有着重要的科学意义，还可为超级稻稳定高产栽培提供理论基础。

Low grain filling efficiency can lead to yield fluctuation and is an important problem in super rice production. It has been reported that moderate drought during grain filling can promote remobilization of pre-stored non-structural carbohydrate (NSC) in the straws and enhance grain filling of inferior spikelets. However, it is still not clear about the molecular mechanism of moderate drought-enhanced NSC remobilization and the regulation of the inferior spikelet grain filling. It has also been known that DNA methylation and demethylation plays important role in the control of gene expressions during seed development and fruit maturation. In this study, we propose to use DNA methylation sequencing, RNA-seq, SWATH-MS and the combined analysis of these comics technologies to investigate all the gene expression and fates of proteins in rice straws and inferior spikelets under moderate drought stress. The key genes from omics results will be further verified by reverse genetic technologies. The enzyme activities of NSC and starch metabolism, plant hormones and drought-related metabolites such as ROS, MDA, proline will be also investigated by using physiological, biochemical and molecular approaches. This project could provide novel insights into the genetic mechanism regulating NSC remobilization and grain filling of rice and identify crucial regulators for future super rice improvement.