植物細胞が細菌病原体を警告する信号メカニズムを発見(Plant ‘first responder’ cells warn neighbors about bacterial pathogens)

2025-12-02 パデュー大学

<関連情報>

• https://ag.purdue.edu/news/2025/12/plant-first-responder-cells-warn-neighbors-about-bacterial-pathogens.html
• https://www.science.org/doi/10.1126/scisignal.adw2270

防御シグナルや傷害によって引き起こされる細胞質Ca2+の局所進行波は、シロイヌナズナにおいて異なるメカニズムによって伝播する Local traveling waves of cytosolic Ca2+ elicited by defense signals or wounding are propagated by distinct mechanisms in Arabidopsis

Weiwei Zhang, Nilay Kumar, Jessica R. Helwig, Alexis Hoerter, […] , and Christopher J. Staiger
Science Signaling  Published:2 Dec 2025
DOI:https://doi.org/10.1126/scisignal.adw2270

Editor’s summary

Pattern-triggered immunity in plants depends on intracellular Ca²⁺ signaling downstream of pattern recognition receptors that are activated by microbe- or damage-associated molecular patterns (MAMPs or DAMPs). Zhang et al. characterized MAMP- and DAMP-induced Ca²⁺ waves in Arabidopsis thaliana cotyledons. The waves initiated in a small number of epidermal cells and slowly propagated to nearby cells in an approximately radial pattern at a constant speed. In contrast, Ca²⁺ waves elicited by wounding of a single cell spread much faster and traveled farther but decreased in speed with distance from the wound. The findings suggest that distinct patterns of Ca²⁺ waves may contribute to stimulus-specific defense responses (see the Focus by Gilroy). —Annalisa M. VanHook

Abstract

Cytosolic calcium ion (Ca²⁺) signatures with specific spatiotemporal patterns play crucial roles in plant responses to biotic and abiotic stresses. The perception of microbe- or damage-associated molecular patterns (MAMPs or DAMPs, respectively) initiates cytosolic Ca²⁺ fluxes that are essential for the induction and spread of pattern-triggered immunity, the first line of plant defense against pathogens, at the cellular, organ, and systemic levels. Here, we quantitatively assessed Ca²⁺ signatures at the single-cell level, as well as the local traveling Ca²⁺ waves induced by uniform MAMP or DAMP treatment of Arabidopsis thaliana cotyledons. MAMPs and DAMPs induced distinct local spatiotemporal Ca²⁺ responses in epidermal pavement cells, with traveling waves of Ca²⁺ consistently initiated from a randomly distributed subset of cells and spreading in an approximately radial pattern. These local traveling waves propagated at a slow but constant speed of ~1 micrometer per second and spread to a limited number of neighboring cells. In contrast, wound-induced traveling waves of Ca²⁺, which are propagated by the diffusion of molecules that activate Ca²⁺ channels, displayed a diffusion-like decay pattern that moved rapidly away from the wounded cell but with diminishing speed over time and distance. Mathematical modeling supported a Ca²⁺-induced Ca²⁺ release mechanism that recapitulated the constant wave speed induced by MAMPs. These findings contribute to a deeper understanding of plant defense–related Ca²⁺ signaling mechanisms, as well as how defense responses are spatially restricted in tissues.