title: Neomycin inhibition of (+)-7-iso-jasmonoyl-L-isoleucine accumulation and signaling.
abstract: The majority of plant defenses against insect herbivores are coordinated by jasmonate (jasmonic acid, JA; (+)-7-iso-jasmonoyl-L-isoleucine, JA-Ile)-dependent signaling cascades. Insect feeding and mimicking herbivory by application of oral secretions (OS) from the insect induced both cytosolic Ca(2+) and jasmonate-phytohormone elevation in plants. Here it is shown that in Arabidopsis thaliana upon treatment with OS from lepidopteran Spodoptera littoralis larvae, the antibiotic neomycin selectively blocked the accumulation of OS-induced Ca(2+) elevation and level of the bioactive JA-Ile, in contrast to JA level. Furthermore, neomycin treatment affected the downstream expression of JA-Ile-responsive genes, VSP2 and LOX2, in Arabidopsis. The neomycin-dependent reduced JA-Ile level is partially due to increased CYP94B3 expression and subsequent JA-Ile turn-over to12-hydroxy-JA-Ile. It is neither due to the inhibition of the enzymatic conjugation process nor to substrate availability. Thus, blocking Ca(2+) elevation specifically controls JA-Ile accumulation and signaling, offering an insight into role of calcium in defense against insect herbivory.
authors.affiliation: Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07745, Jena, Germany, jvadassery@ice.mpg.de.
authors.forename: Jyothilakshmi
authors.initials: J
authors.lastname: Vadassery
authors.forename: Michael
authors.initials: M
authors.lastname: Reichelt
authors.forename: Guillermo H
authors.initials: GH
authors.lastname: Jimenez-Aleman
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Boland
authors.forename: Axel
authors.initials: A
authors.lastname: Mithöfer
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017360:Arabidopsis / Q000737:chemistry* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D003517:Cyclopentanes / Q000737:chemistry / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D060434:Herbivory; D007532:Isoleucine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D009355:Neomycin / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction; D018411:Spodoptera / Q000254:growth & development; D013379:Substrate Specificity
chemical_list: D000900:Anti-Bacterial Agents; D029681:Arabidopsis Proteins; D003517:Cyclopentanes; C463539:VSP2 protein, Arabidopsis; C532883:jasmonoyl-isoleucine; D007532:Isoleucine; D003577:Cytochrome P-450 Enzyme System; C560423:cytochrome P-450 94B3, Arabidopsis; D009355:Neomycin; D002118:Calcium