Efficient uptake, translocation, and distribution of Cu to rice (Oryza sativa) spikelets is crucial for flowering and yield production. However, the regulatory factors involved in this process remain unidentified. In this study, we isolated a WRKY transcription factor gene induced by Cu deficiency, OsWRKY37, and characterized its regulatory role in Cu uptake and transport in rice. OsWRKY37 was highly expressed in rice roots, nodes, leaf vascular bundles, and anthers. Overexpression of OsWRKY37 promoted the uptake and root-to-shoot translocation of Cu in rice under −Cu condition but not under +Cu condition. While mutation of OsWRKY37 significantly decreased Cu concentrations in the stamen, the root-to-shoot translocation and distribution ratio in brown rice affected pollen development, delayed flowering time, decreased fertility, and reduced grain yield under −Cu condition. yeast one-hybrid, transient co-expression and EMSAs, together with in situ RT-PCR and RT-qPCR analysis, showed that OsWRKY37 could directly bind to the upstream promoter region of OsCOPT6 (copper transporter) and OsYSL16 (yellow stripe-like protein) and positively activate their expression levels. Analyses of oscopt6 mutants further validated its important role in Cu uptake in rice. Our study demonstrated that OsWRKY37 acts as a positive regulator involved in the uptake, root-to-shoot translocation, and distribution of Cu through activating the expression of OsCOPT6 and OsYSL16, which is important for pollen development, flowering, fertility, and grain yield in rice under Cu deficient conditions. Our results provide a genetic strategy for improving rice yield under Cu deficient condition.

中文翻译：

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缺铜条件下水稻转录因子OsWRKY37正向调节开花时间和籽粒肥力

水稻 (Oryza sativa) 小穗对铜的有效吸收、易位和分配对于开花和产量至关重要。然而，这一过程中涉及的监管因素仍不清楚。在本研究中，我们分离了一个由铜缺乏诱导的WRKY转录因子基因OsWRKY37，并表征了其在水稻铜吸收和转运中的调节作用。 OsWRKY37 在水稻根、节、叶维管束和花药中高表达。 OsWRKY37 的过表达在−Cu 条件下促进了水稻对Cu 的吸收和从根到茎的易位，但在+Cu 条件下则不然。虽然OsWRKY37突变显着降低了雄蕊中的铜浓度，但糙米的根茎易位和分配比例影响了花粉发育，推迟了开花时间，降低了育性，并降低了-Cu条件下的籽粒产量。酵母单杂交、瞬时共表达和EMSAs，以及原位RT-PCR和RT-qPCR分析表明，OsWRKY37可以直接结合OsCOPT6（铜转运蛋白）和OsYSL16（黄色条纹样蛋白）的上游启动子区域）并积极激活它们的表达水平。对oscopt6突变体的分析进一步验证了其在水稻铜吸收中的重要作用。我们的研究表明，OsWRKY37 通过激活 OsCOPT6 和 OsYSL16 的表达，作为参与 Cu 吸收、根到茎易位和分布的正调节因子，这对于花粉发育、开花、育性和籽粒产量非常重要。缺铜条件下的水稻。我们的结果提供了在缺铜条件下提高水稻产量的遗传策略。