Root hair (RH) size has vital physiological implications, since it influences the surface area of the root and thus the ability of the plant to absorb water and nutrients from the soil. Arabidopsis ROOT HAIR DEFECTIVE 6‐LIKE 4 (RSL4), a bHLH transcription factor, controls the expression of hundreds of RH genes, and RSL4 expression itself can trigger ectopic RH growth. Recent studies reveal an autocrine mechanism governing plant RH cell growth in which the extracellular peptide RAPID ALKALINIZATION FACTOR 1 (RALF1) and receptor FERONIA (FER) act as a central hub between the cell surface and downstream signaling events. RALF1‐FER promotes the phosphorylation of eIF4E1. Then, phosphorylated eIF4E1 further regulates the synthesis of RH proteins, including RSL4, to promote RH growth. High levels of RSL4 exert a negative feedback on RALF1 expression via directly binding to the RALF1 gene promoter, slowing RH growth and determining final RH cell size.

中文翻译：

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通过RALF-FERONIA-RSL4信号通路自发调节根毛大小。

根毛（RH）的大小具有至关重要的生理意义，因为它会影响根部的表面积，从而影响植物从土壤中吸收水分和养分的能力。拟南芥根毛病缺陷6样4（RSL4）是bHLH转录因子，控制数百个RH基因和RSL4的表达表达本身可以触发异位RH增长。最近的研究揭示了控制植物RH细胞生长的自分泌机制，其中细胞外肽快速碱化因子1（RALF1）和受体FERONIA（FER）充当细胞表面和下游信号传导事件之间的中心枢纽。RALF1-FER促进eIF4E1的磷酸化。然后，磷酸化的eIF4E1进一步调节RH蛋白（包括RSL4）的合成，从而促进RH的生长。高水平的RSL4通过直接与RALF1基因启动子结合，减慢RH的生长并确定最终的RH细胞大小，对RALF1的表达产生负反馈。