Kailasam Sakthivel, Chien Wei-Fu, Yeh Kuo-Chen
Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan.
Front Plant Sci. 2019 Jan 31;10:8. doi: 10.3389/fpls.2019.00008. eCollection 2019.
Plant growth requires optimal levels of iron (Fe). Fe is used for energy production, numerous enzymatic processes, and is indispensable for cellular metabolism. Recent studies have established the mechanism involved in Fe uptake and transport. However, our knowledge of Fe sensing and signaling is limited. Dissecting Fe signaling may be useful for crop improvement by Fe fortification. Here, we report two small-molecules, R3 and R6 [where R denotes repressor of ], identified through a chemical screening, whose use blocked activation of the Fe-deficiency response in . Physiological analysis of plants treated with R3 and R6 showed that these small molecules drastically attenuated the plant response to Fe starvation. Small-molecule treatment caused severe chlorosis and strongly reduced chlorophyll levels in plants. Fe content in shoots was decreased considerably by small-molecule treatments especially in Fe deficiency. Small-molecule treatments attenuated the Fe-deficiency-induced expression of the Fe uptake gene . Analysis of FER-LIKE IRON-DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT) and subgroup Ib () gene () expression showed that R3 affects the FIT-network, whereas R6 affects both the FIT and Ib bHLH networks. An assessment of the effects of the structural analogs of R3 and R6 on the induction of Fe-dependent chlorosis revealed the functional motif of the investigated chemicals. Our findings suggest that small-molecules selectively modulate the distinct signaling routes that operate in response to Fe-deficiency. R3 and R6 likely interrupt the activity of key upstream signaling regulators whose activities are required for the activation of the Fe-starvation transcriptional cascade in Arabidopsis roots.
植物生长需要最佳水平的铁（Fe）。铁用于能量生产、众多酶促过程，并且对细胞代谢不可或缺。最近的研究已经确立了铁吸收和运输所涉及的机制。然而，我们对铁感知和信号传导的了解有限。剖析铁信号传导可能有助于通过铁强化来改良作物。在这里，我们报告了通过化学筛选鉴定出的两种小分子R3和R6 [其中R表示……的阻遏物]，它们的使用阻断了……中铁缺乏反应的激活。用R3和R6处理的植物的生理分析表明，这些小分子极大地减弱了植物对铁饥饿的反应。小分子处理导致严重的黄化现象，并使植物中的叶绿素水平大幅降低。小分子处理尤其在缺铁情况下显著降低了地上部的铁含量。小分子处理减弱了铁缺乏诱导的铁吸收基因的表达。对类铁缺乏诱导转录因子（FIT）和Ib亚组（）基因（）表达的分析表明，R3影响FIT网络，而R6影响FIT和Ib bHLH网络。对R3和R6的结构类似物对铁依赖性黄化诱导作用的评估揭示了所研究化学物质的功能基序。我们的研究结果表明，小分子选择性地调节响应铁缺乏而运作的不同信号传导途径。R3和R6可能会中断关键上游信号调节因子的活性，这些因子的活性是拟南芥根中铁饥饿转录级联激活所必需的。
