The plant hormone auxin orchestrates almost all aspects of plant growth and development. AUXIN RESPONSE FACTORs (ARFs) control the transcription of auxin-responsive genes, forming cytoplasmic condensates to modulate auxin sensitivity and diversify auxin response regulation. However, the dynamic control of ARF distribution across different subcellular compartments remains largely obscure. Here, we show that three MULTIPLE C2 DOMAIN AND TRANSMEMBRANE REGION PROTEINs (MCTPs), MCTP3, MCTP4, and MCTP6, control ARF nucleocytoplasmic partitioning and determine lateral root development. MCTP3/4/6 are highly expressed in lateral roots and specifically interact with ARF7 and ARF19 to dissolve their cytoplasmic condensates. This promotes ARF nuclear localization in lateral root primordia and enhances auxin signaling during lateral root formation. Our findings confer MCTP as a key switch to modulate auxin responses and outline an MCTP-ARF signaling cascade that is crucial for the establishment of the plant root system.

中文翻译：

---

MCTP 控制侧根发育过程中生长素反应因子的核质分配


植物激素生长素几乎协调植物生长和发育的所有方面。生长素反应因子 （ARF） 控制生长素反应基因的转录，形成细胞质凝聚物以调节生长素敏感性并使生长素反应调节多样化。然而，ARF 在不同亚细胞区室中分布的动态控制在很大程度上仍然不清楚。在这里，我们展示了三种多 C2 结构域和跨膜区蛋白 （MCTP），MCTP3、MCTP4 和 MCTP6 控制 ARF 核质分配并决定侧根发育。MCTP3/4/6 在侧根中高度表达，并与 ARF7 和 ARF19 特异性相互作用以溶解它们的细胞质凝聚物。这促进了 ARF 核在侧根原基中的定位，并增强了侧根形成过程中的生长素信号传导。我们的研究结果赋予 MCTP 作为调节生长素反应的关键开关，并概述了对建立植物根系至关重要的 MCTP-ARF 信号级联。