Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2006
Publication Date: 6/6/2006
Citation: Schmelz, E.A., Carroll, M.J., LeClere, S.L., Phipps, S.M., Meredith, J.A., Chourey, P.S., Alborn, H.T., Teal, P.E. 2006. Fragments of ATP synthase mediate plant perception of insect attack. Proceedings of the National Academy of Sciences. 103(23):8894-8899. Interpretive Summary: In response to insect and pathogen attack, plants often produce rapid biochemical defenses that reduce further damage and yield losses. Targeted improvements in naturally occurring crop resistance will require a mechanistic understanding of these induced defenses. Caterpillar oral secretions (OS) induce rapid biochemical responses in legume crops, such as cowpea (Vigna unguiculata), yet previously identified insect-derived elicitors displayed no activity. It was hypothesized that unidentified and unknown factors in the OS were responsible for this plant perception of insect attack. Scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL, have discovered an 11 amino acid peptide, termed inceptin, in caterpillar oral secretions that triggers defenses in cowpea and beans (Phaseolus vulagris) when applied to leaves at extremely low concentrations. Inceptin is a caterpillar digestive fragment of the essential plant enzyme, chloroplastic ATP synthase. The detection of insect attack mediated by peptide fragments of a plant enzyme demonstrates great similarities with modes of plant phytopathogenic bacteria perception. Importantly, the discovery of inceptin opens the door for the development and genetic manipulation of plants with improved defense responses against caterpillar attack.
Technical Abstract: Pathogen and insect attack induce targeted plant biochemical defenses through the direct perception of pest-derived elicitors. Indirect pathogen recognition also occurs through the surveillance of inappropriately proteolyzed plant proteins. The analogous indirect perception of insects is unknown. We isolated a peptide [+ICDINGVCVDA-] from caterpillar oral secretions(OS) that induces defense-related phytohormone cascades, volatiles and protease inhibitor(PIN) transcripts in cowpea (Vigna unguiculata). Active at 1 fmol leaf-1, this proteolytic product is from a regulatory domain of chloroplastic ATP synthase gamma-subunit (cATPC). Initiation of insect perception via this peptide, termed inceptin, demonstrates that plants also indirectly perceive insects via perturbations in their proteome.