@unpublished{23175,
  abstract     = {Plants must continually balance growth with arrest, especially under stress. Auxin signaling acts as a central regulatory hub in this process, yet the mechanisms that dynamically tune early auxin signalling in real time remain unknown. Here, we used the light-gated, Ca2+-permeable Channelrhodopsin 2 variant XXM2.0 to optogenetically impose defined Ca2+ signatures on Arabidopsis root cells. Repetitive light activation triggered cytosolic Ca2+ signals that in turn suppressed auxin-induced membrane depolarization and Ca2+ transients. Moreover, prolonged optogenetic Ca2+ stimulation affects auxin-responsive transcriptional reprogramming. As phenotypic output, reversible inhibition of root growth by suppressing cell division and elongation was observed. We further identify a candidate CaM7–CNGC14 module that likely mediates Ca2+-dependent gating of early auxin signalling. Our study thus introduces a synthetic biology approach to decompose calcium–auxin crosstalk in plant cells, and demonstrates that optogenetically imposed cytosolic Ca2+ signals act as dynamic regulators of auxin susceptibility in roots.},
  author       = {Song, Huifang and Baudon, Angel and Freund, Matthias and Randuch, Marek and Pěnčík, Aleš and Ondřej, Novák and He, Zhaohui and Kaufmann, Kerstin and Li, Nan and Gilliham, Matthew and Friml, Jiří and Hedrich, Rainer and Huang, Shouguang},
  booktitle    = {bioRxiv},
  title        = {{Ca2+ signature gates early auxin signaling in Arabidopsis roots}},
  doi          = {10.1101/2025.10.04.680446},
  year         = {2026},
}