Calcium Signaling in Plant-Insect Interactions

In plant–insect interactions, calcium (Ca(2+)) variations are among the earliest events associated with the plant perception of biotic stress. Upon herbivory, Ca(2+) waves travel long distances to transmit and convert the local signal to a systemic defense program. Reactive oxygen species (ROS), Ca(2+) and electrical signaling are interlinked to form a network supporting rapid signal transmission, whereas the Ca(2+) message is decoded and relayed by Ca(2+)-binding proteins (including calmodulin, Ca(2+)-dependent protein kinases, annexins and calcineurin B-like proteins). Monitoring the generation of Ca(2+) signals at the whole plant or cell level and their long-distance propagation during biotic interactions requires innovative imaging techniques based on sensitive sensors and using genetically encoded indicators. This review summarizes the recent advances in Ca(2+) signaling upon herbivory and reviews the most recent Ca(2+) imaging techniques and methods.