The phytohormone auxin plays a pivotal role in governing plant growth and development. Although the TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX (TIR1/AFB) receptors function in both the nucleus and cytoplasm, the mechanism governing the distribution of TIR1/AFBs between these cellular compartments remains unknown. In this study, we demonstrate that auxin-mediated oxidation of TIR1/AFB2 is essential for their targeting to the nucleus. We showed that small active molecules, reactive oxygen species (ROS) and nitric oxide (NO), are indispensable for the nucleo-cytoplasmic distribution of TIR1/AFB2 in trichoblasts and root hairs. Further studies revealed that this process is regulated by the FERONIA receptor kinase–NADPH oxidase signaling pathway. Interestingly, ROS and NO initiate oxidative modifications in TIR1 and AFB2, facilitating their subsequent nuclear import. The oxidized forms of TIR1 and AFB2 play a crucial role in enhancing the function of TIR1 and AFB2 in transcriptional auxin responses. Collectively, our study reveals a novel mechanism by which auxin stimulates the transport of TIR1/AFB2 from the cytoplasm to the nucleus, orchestrated by the FERONIA–ROS signaling pathway.

中文翻译：

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FERONIA 介导的 TIR1/AFB2 氧化刺激拟南芥中的生长素信号传导

植物激素生长素在控制植物生长和发育中起着关键作用。尽管转运抑制剂反应 1/生长素信号 F-BOX (TIR1/AFB) 受体在细胞核和细胞质中均发挥作用，但控制 TIR1/AFB 在这些细胞区室之间分布的机制仍不清楚。在这项研究中，我们证明了生长素介导的 TIR1/AFB2 氧化对于它们靶向细胞核至关重要。我们发现活性小分子、活性氧（ROS）和一氧化氮（NO）对于毛细胞和根毛中 TIR1/AFB2 的核质分布是不可或缺的。进一步的研究表明，这一过程受到FERONIA受体激酶-NADPH氧化酶信号通路的调节。有趣的是，ROS 和 NO 启动 TIR1 和 AFB2 的氧化修饰，促进它们随后的核输入。 TIR1 和 AFB2 的氧化形式在增强 TIR1 和 AFB2 在转录生长素反应中的功能方面发挥着至关重要的作用。总的来说，我们的研究揭示了生长素刺激 TIR1/AFB2 从细胞质到细胞核的转运的新机制，该机制由 FERONIA-ROS 信号通路协调。