Plants signal danger through nervelike process

Abstract

When a caterpillar, or some other pesky herbivore, nibbles on a leaf, the plant sends danger signals to its farthest fronds to activate the plant’s defense mechanisms, such as producing noxious compounds to chase off the pest or turning on pathways to heal damaged tissues. Now a research team led by Masatsugu Toyota at Saitama University reports that this signaling happens through a nervelike process involving glutamate, which is a neurotransmitter in mammals (Science 2018, DOI: 10.1126/science.aat7744). The team either cut the stems of or enticed caterpillars to munch on Arabidopsis plants engineered to express a protein sensor that fluoresces when it binds calcium ions. The plant’s defense mechanisms are triggered in part by increases in calcium ion concentration. Using fluorescent microscopy, the team detected spikes in calcium ion levels immediately at the sites of damage and two minutes later in distant leaves. The timing was too fast to be