Shared signals and the potential for phylogenetic espionage between plants and animals

Until recently, the study and understanding of plant and animalsignalling and response mechanisms have developed independently.Recent biochemical and molecular work is producing a growinglist of elements involved in responses to biotic and abioticstimuli that are very similar across kingdoms. Some of the moreinteresting examples of these include prostaglandin/octadecanoid-mediatedresponses to wounding, steroid-based signalling systems, andpathogen-recognition mechanisms. Some of these similaritiesprobably represent evolutionary convergence; others may be ancestralto plants and animals. Ecological and evolutionary implicationsof such overlaps include the existence of pathogens that cancause disease in plants and animals, the ability of herbivoresto manipulate plant responses, usurpation of microbial mechanismsand genes by herbivorous animals and plants, evolution of plantdefenses exploiting shared signals in animals, and the medicinaluse of plants by humans. Comparative study of the signallingand response mechanisms used by plants, animals, and microbesprovides novel and useful insights to the ecology and evolutionof interactions across kingdoms.