铁是植物生长发育所必需的微量元素，也是维持人类健康所必需的营养元素。挖掘铁信号途径的关键调控基因并阐明其功能，对于铁高效利用和富铁作物新品种的培育具有重要意义。OsFIT是一个正调控水稻铁稳态的关键转录因子，但其在缺铁条件下是如何被转录激活的并不清楚。我们利用酵母单杂交筛选到一个可以结合OsFIT启动子的功能未知的转录因子，将其命名为OsURF（Oryza sativa Upstream Regulator of FIT）。OsURF的功能缺失导致典型的缺铁敏感表型和缺铁响应基因表达的下调，表明OsURF正调控铁稳态。在此基础上，本项目拟采用分子生物学、遗传学及生物化学的方法和手段，进一步研究OsURF与OsFIT的遗传关系，并系统解析OsURF在铁稳态调控中的生物学功能及分子机制。研究结果有望进一步丰富水稻铁稳态调控网络，同时为富铁水稻新品种的培育提供基因资源和理论依据。

Iron (Fe) is an essential micronutrient for both plants and human. Identification and characterization of the key components in the Fe signaling pathway will contribute to the cultivation of iron-rich crops. OsFIT (Oryza sativa Fer-Like Fe Deficiency-Induced Transcription Factor) is a crucial positive regulator of Fe homeostasis in rice; however, it remains unclear how the transcription of OsFIT is activated by Fe deficiency. A transcription factor with unknown functions, which bond to the promoter of OsFIT in the yeast-one-hybrid assays, was identified and named OsURF (Oryza sativa Upstream Regulator of FIT). Loss-of-function mutation of OsURF caused the enhanced sensitivity to Fe deficiency and the reduced expression of Fe deficiency responsive genes, suggesting that OsURF positively regulates Fe homeostasis. This project will further reveal the molecular mechanism of OsURF mediating Fe homeostasis by the combination of molecular biology, plant physiology and genetics. The predicted achievement will shed light on the Fe signaling network in rice, and contribute to the molecular breeding of iron-rich rice.