Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2007
Publication Date: 8/7/2007
Citation: Alborn, H.T., Hansen, T.H., Jones, T.H., Bennett, D.C., Tumlinson, J.H., Schmelz, E.A., Teal, P.E. 2007. Disulfooxy fatty acids from the American bird grasshopper Schistocerca americana, elicitors of plant volatiles. Proceedings of the National Academy of Sciences. 104(32):12976-12981. Interpretive Summary: In response to insect feeding plants often produce biochemical defenses that reduce further damage and yield losses. Many plants respond to insect damage by an induced release of volatiles that can serve as a direct defense as well as serve as long range attractants for natural enemies of the pest. Scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL, have discovered a new class of chemical compounds (named caeliferins) from the regurgitant of the grasshopper, Schistocerca Americana, that induce corn seedlings to emit blends of volatile organic compounds, qualitatively and quantitatively similar to the blends released by grasshopper- and caterpillar-damaged seedlings. Caeliferins that are the first identified non-lepidopteran elicitors were also found in other grasshoppers in the suborder Caelifera, but not so far in any other species in the order Orthoptera or in any other investigated insects. This new category of insect herbivore-produced elicitors of plant responses provides further evidence of the ability of plants to detect and respond to a broad range of compounds produced by insect herbivores. Importantly, the discovery of new insect produced elicitors increases our ability to understand and manipulate the biochemistry behind plants defensive strategies with the goal to improve as well as optimize their defensive responses to attack by phytophagous insects.
Technical Abstract: A new class of compounds has been isolated from the regurgitant of the grasshopper species Schistocerca americana. These compounds (named here caeliferins) are comprised of saturated and monounsaturated, sulfated alpha-hydroxy fatty acids in which the omega carbon is functionalized with either a sulfated hydroxyl or a carboxyl conjugated to glycine via an amide bond. The regurgitant contains a series of these compounds with fatty acid chains of 15 to 20 carbons and in varying proportions. Of these, the 16-carbon analogs are predominant and also most active when applied to damaged leaves of corn seedlings. The seedlings are induced to emit blends of volatile organic compounds, similar to the blends released by grasshopper and Lepidoptera caterpillar damaged seedlings. Caeliferins are the first non-lepidopteran elicitors identified in insect herbivores. This adds a new category of insect herbivore-produced elicitors of plant responses, providing further evidence of the ability of plants to detect and respond to a broad range of insect herbivore produced compounds.