title: Molecular interactions between the specialist herbivore Manduca sexta (Lepidoptera, Sphingidae) and its natural host Nicotiana attenuata. III. Fatty acid-amino acid conjugates in herbivore oral secretions are necessary and sufficient for herbivore-specific plant responses.
abstract: Feeding by the tobacco specialist Manduca sexta (Lepidoptera, Sphingidae) and application of larval oral secretions and regurgitant (R) to mechanical wounds are known to elicit: (a) a systemic release of mono- and sesquiterpenes, (b) a jasmonate burst, and (c) R-specific changes in transcript accumulation of putatively growth- and defense-related mRNAs in Nicotiana attenuata Torr. ex Wats. We identified several fatty acid-amino acid conjugates (FACs) in the R of M. sexta and the closely related species Manduca quinquemaculata which, when synthesized and applied to mechanical wounds at concentrations comparable with those found in R, elicited all three R-specific responses. Ion-exchange treatment of R, which removed all detectable FACs and free fatty acids (FAs), also removed all detectable activity. The biological activity of ion-exchanged R could be completely restored by the addition of synthetic FACs at R-equivalent concentrations, whereas the addition of FAs did not restore the biological activity of R. We conclude that the biological activity of R is not related to the supply of FAs to the octadecanoid cascade for endogenous jasmonate biosynthesis, but that FACs elicit the herbivore-specific responses by another mechanism and that the insect-produced modification of plant-derived FAs is necessary for the plant's recognition of this specialized herbivore.
authors.affiliation: Department of Molecular Ecology, Max Planck Institut for Chemical Ecology, Carl Zeiss Promenade 10, D-07745 Jena, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Halitschke
authors.forename: U
authors.initials: U
authors.lastname: Schittko
authors.forename: G
authors.initials: G
authors.lastname: Pohnert
authors.forename: W
authors.initials: W
authors.lastname: Boland
authors.forename: I T
authors.initials: IT
authors.lastname: Baldwin
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001643:Bridged Bicyclo Compounds / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000378:metabolism; D006790:Host-Parasite Interactions / Q000502:physiology*; D018402:Manduca / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D008969:Molecular Sequence Data; D054883:Oxylipins; D014026:Nicotiana / Q000469:parasitology*; D014158:Transcription, Genetic
chemical_list: D000596:Amino Acids; D001643:Bridged Bicyclo Compounds; D003517:Cyclopentanes; D005230:Fatty Acids, Nonesterified; D005232:Fatty Acids, Volatile; D054883:Oxylipins; C423904:alpha-bergamotene; C011006:jasmonic acid