n-linolenoyl-l-glutamine and volicitin

Plants attacked by insect herbivores release a blend of volatile organic compounds (VOCs) that serve as chemical cues for host location by parasitic wasps, natural enemies of the herbivores. Volicitin, N-(17-hydroxylinolenoyl)-L-glutamine, is one of the most active VOC elicitors found in herbivore regurgitants. Our previous study revealed that hydroxylation on the 17th position of the linolenic acid moiety of N-linolenoyl-L-glutamine increases by more than three times the elicitor activity in corn plants. Here, we identified N-(18-hydroxylinolenoyl)-L-glutamine (18OH-volicitin) from larval gut contents of tobacco hornworm (THW), Manduca sexta. Eggplant and tobacco, two solanaceous host plants of THW larvae, and corn, a non-host plant, responded differently to this new elicitor. Eggplant and tobacco seedlings emitted twice the amount of VOCs when 18OH-volicitin was applied to damaged leaf surfaces compared to N-linolenoyl-L-glutamine, while both these fatty acid amino acid conjugates (FACs) elicited a similar response in corn seedlings. In both solanaceous plants, there was no significant difference in the elicitor activity of 17OH- and 18OH-volicitin. Interestingly, other lepidopteran species that have 17OH-type volicitin also attack solanaceous plants. These data suggest that plants have developed herbivory-detection systems customized to their herbivorous enemies.

Topics: alpha-Linolenic Acid; Animals; Glutamine; Herbivory; Linolenic Acids; Manduca; Nicotiana; Plant Physiological Phenomena; Plants; Seedlings; Solanum melongena; Volatile Organic Compounds; Zea mays

The recognition of insect and pathogen attack requires the plant's ability to perceive chemical cues generated by the attacker. In contrast to the recognition of microbe-associated molecular patterns and effectors, little is known about the molecular recognition of herbivore-associated elicitors (HAEs) and the signaling mechanisms operating in plants after their perception. HAE perception depends strongly on the natural history of both plants and insects and it is therefore expected that many of the responses induced by different HAEs are specific to the species involved in the interaction. The interaction between Nicotiana attenuata and the specialist lepidopteran Manduca sexta presents a relevant biological system to understand HAE perception and signal transduction systems in plants.

Topics: alpha-Linolenic Acid; Animals; Cyclopentanes; Feeding Behavior; Gene Expression Regulation, Plant; Genes, Plant; Glutamine; Host-Parasite Interactions; Linolenic Acids; Manduca; Nicotiana; Oxylipins; Plant Leaves; Signal Transduction

The indole-3-glycerol phosphate lyase Igl is the structural gene of volatile indole biosynthesis in the tritrophic interaction in maize. The gene is activated on transcriptional level with the same kinetics and to the same level by the fatty acid-amino acid conjugates (FAC's) volicitin (17S)-(N-(17-hydroxylinolenoyl)-L-glutamine) and N-linolenoyl-L-glutamine. Both conjugates are present in the regurgitates of herbivorous caterpillars. Modifications of the fatty acid moiety of the FACs greatly reduces the elicitation of Igl and only the L-stereo-isomer of the FACs shows biological activity in the system. Volicitin treatment leads to a fast increase of AOS and AOC transcription levels and methyl jasmonate application induces Igl transcription. Hence, the induction of jasmonate biosynthesis appears to be an integral part of the elicitor mediated increase of Igl gene transcription.

Topics: Acetates; alpha-Linolenic Acid; Amino Acids, Cyclic; Animals; Aristolochic Acids; Aspirin; Cyclooxygenase Inhibitors; Cyclopentanes; Genes, Plant; Glutamine; Indole-3-Glycerol-Phosphate Synthase; Indoles; Intramolecular Oxidoreductases; Lepidoptera; Linolenic Acids; Oxylipins; Pyrazoles; Stereoisomerism; Structure-Activity Relationship; Transcriptional Activation; Zea mays