Diffusion and bulk flow of amino acids mediate calcium waves in plants

Abstract

In plants, a variety of stimuli trigger long-range calcium signals that travel rapidly along the vasculature to distal tissues via poorly understood mechanisms. Here, we use quantitative imaging and analysis to demonstrate that traveling calcium waves are mediated by diffusion and bulk flow of amino acid chemical messengers. We propose that wounding triggers release of amino acids that diffuse locally through the apoplast, activating the calcium-permeable channel GLUTAMATE RECEPTOR-LIKE 3.3 as they pass. Over long distances through the vasculature, the wound-triggered dynamics of a fluorescent tracer show that calcium waves are likely driven by bulk flow of a channel-activating chemical. We observed that multiple stimuli trigger calcium waves with similar dynamics, but calcium waves alone cannot initiate all systemic defense responses, suggesting that mobile chemical messengers are a core component of complex systemic signaling in plants.

Integration of Electrical Signals and Phytohormones in the Control of Systemic Response

“…GLR1.2 and GLR1.3 are positive regulators of JA biosynthesis upon cold stress [54]. As seen, GLRs mediating [Ca 2+ ] cyt elevation are universal positive regulators of JA production under various biotic and abiotic stresses, although one study also showed that GLR-mediated Ca 2+ waves alone are insufficient to trigger JA signaling [55].…”

A bi-kinase module sensitizes and potentiates plant immune signaling

“…3F). The speed of this newly identified flg22 response is significantly slower compared to 200-1000 µM/s that have been determined for systemic electrical, ROS or Ca 2+ signals propagating through vascular bundles in response to other stimuli (20)(21)(22)(23)(24)(25)(26)(27). Therefore, this value likely defines the cell-to-cell transcellular propagation velocity of PAMP triggered Ca 2+ /ROS signals.…”

Damage activatesEVG1to suppress vascular differentiation during regeneration inArabidopsis thaliana

“…Here, we identified EVG1 as a stress responsive gene that repressed vascular differentiation. Upon wounding, induction of EVG1 was rapid, occurring between 10 minutes to 6 hours after cutting (Figure 1 and 6), suggesting hormones, reactive oxygen species or control by other rapid response factors such as cell wall or turgor pressure changes (Hoermayer et al, 2020;Zhang et al, 2022;Bellandi et al, 2022).…”