# Optogenetic Ca2+ signals in Arabidopsis roots suppress auxin responses and reversibly slow growth

- Published: 2026-11-05 01:57 UTC
- Section: Life & Health › Biology & biochemistry
- Tags: optogenetics in plants, Ca2+ signature, auxin signaling, Arabidopsis roots, XXM2.0 channelrhodopsin, CNGC14, CaM7, root growth inhibition, calcium–auxin crosstalk
- URL: https://realtech.media/news/rt-6fb1a0d6c2ba9be1459f7b38_optogenetic_ca2_signals/

**Authors used the light-gated channel XXM2.0 to impose Ca2+ signals on Arabidopsis root cells and tested how calcium modulates the response to exogenous auxin.**

![Optogenetic Ca2+ signals in Arabidopsis roots suppress auxin responses and reversibly slow growth](https://thumb.wikimedia.org/wikipedia/commons/thumb/e/e9/Arabidopsis_arenosa_kz24.jpg/1920px-Arabidopsis_arenosa_kz24.jpg?utm_source=commons.wikimedia.org&utm_campaign=imageinfo&utm_content=thumbnail)
*Krzysztof Ziarnek, Kenraiz, Wikimedia Commons, CC BY-SA 4.0*

A research team reported in Nature Communications that light-controlled calcium signals in Arabidopsis root cells reduce the response to exogenously applied auxin. The authors expressed XXM2.0, a Ca2+-permeable variant of Channelrhodopsin 2, to impose defined cytosolic Ca2+ signatures on living roots [1]. According to the authors, repetitive light activation triggered cytosolic Ca2+ signals, which suppressed membrane depolarization and Ca2+ transients evoked by exogenous auxin [1].

Plants must balance growth with arrest, especially under stress, and auxin signaling is a central regulatory hub in this process. The mechanisms that tune auxin signaling in real time were unknown. Until now, plant Ca2+ signals have mostly been provoked by chemical probes or by changes in the composition of the extracellular solution. The authors note that these approaches are often invasive, prone to off-target effects, or inevitably alter the plasma membrane potential [1].

## Light-gated channels in root cells

XXM2.0 and the light-gated anion channel GtACR1 were expressed under the UBQ10 promoter. Both were fused at the C-terminus to eYFP and combined with a retinal-generating dioxygenase. Confocal microscopy showed that both channels localized predominantly to the plasma membrane of root cells [1].

The team recorded membrane potential with sharp microelectrodes in the meristematic zone of 3–5-day-old seedlings. A 1-s blue light pulse (100 µE) electrically excited cells expressing either XXM2.0 or GtACR1. Trains of ten pulses at 30-s intervals produced repeated depolarizations, reproducible within the same cell and between different seedlings [1]. Ca2+ signals in XXM2.0 seedlings were followed with the R-GECO1 sensor [1].

## Auxin response and root growth

Prolonged optogenetic Ca2+ stimulation affected auxin-responsive transcriptional reprogramming. As a phenotypic output, the authors observed reversible inhibition of root growth through suppression of cell division and elongation [1].

The authors also identified a candidate CaM7–CNGC14 module that likely mediates Ca2+-dependent gating of responsiveness to exogenous auxin and Ca2+-dependent root growth inhibition [1]. They describe the work as a synthetic biology approach to decompose calcium–auxin crosstalk in plant cells. In their conclusion, optogenetically imposed cytosolic Ca2+ signals act as dynamic regulators of auxin susceptibility in roots [1].

## Sources

1. [Nature Communications](https://doi.org/10.1038/s41467-026-78361-8)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-6fb1a0d6c2ba9be1459f7b38_optogenetic_ca2_signals/