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.