碳水化合物从叶片（源）到籽粒（库）的有效运输（流）对水稻产量的形成起着重要作用。蔗糖是水稻碳水化合物运输的主要形式，因此水稻蔗糖运输对于籽粒的形成有着重要作用。我们分离到一个未知功能基因（GFD1）突变导致的水稻灌浆缺陷突变体，初步分析显示，GFD1蛋白属于SWEET蛋白家族，具有蔗糖转运活性，同时定位于细胞质膜上。这表明该蛋白很可能参与了水稻的蔗糖运输。我们将在此基础上，采用分子生物学、细胞学、植物生理学以及生物化学方法，研究GFD1蛋白的蔗糖转运特性、基因表达特性、相互作用蛋白以及影响水稻灌浆的生理过程，阐释GFD1蛋白功能和影响水稻籽粒灌浆的分子机制，为通过加强蔗糖从源到库的有效运输提高水稻产量提供新的线索。

The rice yield depends on the carbohydrate transportation (Flow) from leaves (Source) to seeds (Sink). Sucrose is the main form of the carbohydrate transportation，so the sucrose transportation is important for the rice yield formation. A grain filling defect rice mutant was due to a function unknown gene (GFD1, Grain Filling Defect1) mutation. Our study had shown that GFD1 protein had sucrose transporter activity and was located at the plasma membrane. These results suggested that GFD1 protein involved in the sucrose transportation of rice. The methods of molecular biology, cytology, plant physiology and biochemistry will be introduced in this study. Then we will investigate the sucrose transport activity, gene expression characters, interactive protein of GFD1 and the grain filling process of gfd1 mutant, and try to explicit the function of GFD1 protein and the molecular mechanism of grain filling regulation with GFD1. Our study will provide new clue to improve the rice yield by enhancing the sucrose transportation from source to sink.