@unpublished{23174,
  abstract     = {Roots must continuously adapt their growth and have evolved the ability to rapidly respond to diverse environmental and hormonal cues, including the phytohormone auxin. Auxin-induced cellular responses involve membrane depolarization, cytosolic calcium (Ca²⁺) elevation, and extracellular pH increase, but how these processes lead to rapid growth regulation remains unclear. Here, we show that cytosolic Ca²⁺ acts as a universal signal integrating diverse cues for rapid regulation of root growth. Using live imaging, microfluidics, and optogenetics in Arabidopsis, we demonstrate that a swift rise in cytosolic Ca²⁺ is the primary target of auxin signaling affecting growth inhibition. Disruption of Ca²⁺ influx abolishes these responses, whereas light-gated Ca²⁺ influx from the apoplast or endoplasmic reticulum stores inhibits growth. Multiple unrelated stimuli—including auxin, extracellular ATP, RALF peptides, and hydrogen peroxide—converge on this Ca²⁺-dependent mechanism. Cytosolic Ca²⁺ elevation thus represents a necessary and sufficient step for rapid growth inhibition, revealing a unifying principle of root signaling.},
  author       = {Randuch, Marek and Kulich, Ivan and Vladimirtsev, Dmitrii and Huang, Shouguang and Hedrich, Rainer and Friml, Jiří},
  booktitle    = {bioRxiv},
  title        = {{Cytosolic Ca2+ as a universal signal for rapid root growth regulation}},
  doi          = {10.1101/2025.10.17.683082},
  year         = {2025},
}