Glutamate triggers long-distance, calcium-based plant defense signaling

Rapid, long-distance signaling in plants A plant injured on one leaf by a nibbling insect can alert its other leaves to begin anticipatory defense responses. Working in the model plant Arabidopsis , Toyota et al. show that this systemic signal begins with the release of glutamate, which is perceived by glutamate receptor–like ion channels (see the Perspective by Muday and Brown-Harding). The ion channels then set off a cascade of changes in calcium ion concentration that propagate through the phloem vasculature and through intercellular channels called plasmodesmata. This glutamate-based long-distance signaling is rapid: Within minutes, an undamaged leaf can respond to the fate of a distant leaf. Science , this issue p. 1112 ; see also p. 1068