背景回顾：Nutrient sensing and signaling are essential for adjusting growth and development to available resources. Deprivation of the essential mineral phosphorus (P) inhibits root growth. 

提出问题：The molecular processes that sense P limitation to trigger early root growth inhibition are not known yet. Target of rapamycin (TOR) kinase is a central regulatory hub in eukaryotes to adapt growth to internal and external nutritional cues. How nutritional signals are transduced to TOR to control plant growth remains unclear. 

主要发现：Here, we identify Arabidopsis-root-specific kinase 1 (ARSK1), which attenuates initial root growth inhibition in response to P limitation. 

结果：We demonstrate that ARSK1phosphorylates and stabilizes the regulatory-associated protein of TOR 1B (RAPTOR1B), a component of the TOR complex 1, to adjust root growth to P availability. 

结论：These findings uncover signaling components acting upstream of TOR to balance growth to P availability.

养分感知和信号传导对于调整生长发育以适应可用资源至关重要。必需矿物质磷（P）的缺乏抑制了根系的生长。感知磷限制以诱导早期根系生长抑制的分子过程尚不清楚。TOR激酶是真核生物根据内外信号调整生长的调节中枢。但是，营养信号是如何传导到TOR以控制植物生长的，目前尚不清楚。本文中，作者在拟南芥中鉴定到了一个根特异性的激酶ARSK1，其能够减弱响应低磷的初始根生长抑制。作者发现，ARSK1能够磷酸化并稳定TOR复合物1组分RAPTOR1B蛋白，从而调节根系生长以适应可利用磷。这些发现揭示了TOR上游的信号传导组分，以根据可利用磷平衡植物的生长。