Effect of host plant on defense elicitors

The ability of plants to detect herbivores and respond with appropriate defenses is essential for their survival. Plants are exposed to a wide array of herbivores, and the ways in which they recognize and respond to such a diverse array of antagonists is not fully understood. This research addresses the possibility that plants may use a relatively general recognition system that allows them to respond appropriately to different classes of insect herbivores. We hypothesize that plants may “tag” or modify insect saliva and this in turn affects the plant’s ability to detect herbivory probably in a way that allows them to generalize their responses to attack. In order to test this hypothesis, cabbage looper (Trichoplusia ni) larvae were grown on tomato (Solanum lycopersicum) and cabbage (Brassica oleracea var capitata). Then, tomato and cabbage plants were challenged with larvae that had been feeding on either of these plants. Samples were taken 12 and 24 hours after treatment and analyzed for polyphenol oxidase activity. These experiments will determine if insects trigger defenses differentially depending on which species they had fed on previous to experiment. This research is a key first step toward improved insight into the complex mechanisms through which plants recognize and respond to insect herbivores.