systemic signalling

The dissemination of chemical signals throughout a plant in response to injury or infection of part of the plant. The signals trigger a systemic defence response that helps the plant to combat spread of the infection or restrict further injury by herbivorous animals. For example, insects chewing on a leaf of a tomato plant elicit the release of a systemic signal that is transported throughout the plant and causes the plant to express genes encoding proteinase inhibitors that interfere with the insect's digestion. Foremost among these systemic signals are the jasmonates and a group of peptides called systemins. See also systemic acquired resistance.