OsIRO3 negatively regulates Fe homeostasis by repressing the expression of OsIRO2
OsIRO3 negatively regulates Fe homeostasis by repressing the expression of OsIRO2
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DOI：
10.1111/tpj.15864
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发表时间：
2022-06-30
期刊：
影响因子：
7.2
通讯作者：
Liang, Gang
中科院分区：
文献类型：
--
作者：
Li, Chenyang;Li, Yang;Liang, Gang
铁 (Fe) 对于作物生产力和质量至关重要。然而，缺铁现象在世界范围内普遍存在，特别是在碱性土壤中。植物已经进化出复杂的机制来承受缺铁的条件。 Oryza sativa 铁相关 BHLH 转录因子 3 (OsIRO3/OsbHLH63) 已被确定为缺铁反应信号传导的负调节因子；然而，其根本机制仍不清楚。在本研究中，我们构建了两个 iro3 突变体，它们在缺铁条件下发育出具有坏死病斑的叶子。 OsIRO3 功能丧失导致根部缺铁相关基因上调。 Fe 浓度测量表明，iro3 突变体仅在缺铁条件下增加地上部 Fe 浓度。进一步分析表明，OsIRO3 直接调节铁相关 BHLH 转录因子 2 (OsIRO2) 的表达，该因子编码 Fe 吸收系统的正调节因子。进一步研究表明，OsIRO3 与铁稳态正调节因子 1 (OsPRI1) 和 OsPRI2 相互作用。 OsIRO3 抑制它们对 OsIRO2 的转录激活。 OsIRO3 包含一个 EAR 基序，它招募 TOPLESS/TOPLESS-RELATED (OsTPL/OsTPRs) 辅阻遏物。 EAR 基序的突变减弱了 OsIRO3 的抑制能力。这项工作揭示了 OsIRO3 调节水稻 Fe 稳态的分子机制。
Iron (Fe) is crucial for crop productivity and quality. However, Fe deficiency is prevalent worldwide, particularly in alkaline soil. Plants have evolved sophisticated mechanisms to withstand Fe-deficient conditions. Oryza sativa IRON-RELATED BHLH TRANSCRIPTION FACTOR 3 (OsIRO3/OsbHLH63) has been identified as a negative regulator of Fe deficiency response signaling; however, the underlying mechanism remains unclear. In the present study, we constructed two iro3 mutants, which developed leaves with necrotic lesions under Fe-deficient conditions. Loss-of-function of OsIRO3 caused upregulation of Fe deficiency-associated genes in the root. Fe concentration measurements showed that the iro3 mutants had increased shoot Fe concentration only under Fe-deficient conditions. Further analysis revealed that OsIRO3 directly regulated the expression of IRON-RELATED BHLH TRANSCRIPTION FACTOR 2 (OsIRO2), which encodes a positive regulator of the Fe uptake system. Further investigation demonstrated that OsIRO3 interacted with POSITIVE REGULATOR OF IRON HOMEOSTASIS 1(OsPRI1) and OsPRI2, and. OsIRO3 repressed their transcription activation towards OsIRO2. OsIRO3 contains an EAR motif, which recruits the TOPLESS/TOPLESS-RELATED (OsTPL/OsTPRs) corepressors. Mutation of the EAR motif attenuated the repression ability of OsIRO3. This work sheds light on the molecular mechanism by which OsIRO3 modulates Fe homeostasis in rice.