title: Mutations in jasmonoyl-L-isoleucine-12-hydroxylases suppress multiple JA-dependent wound responses in Arabidopsis thaliana.
abstract: Plants rapidly perceive tissue damage, such as that inflicted by insects, and activate several key defense responses. The importance of the fatty acid-derived hormone jasmonates (JA) in dictating these wound responses has been recognized for many years. However, important features pertaining to the regulation of the JA pathway are still not well understood. One key unknown is the inactivation mechanism of the JA pathway and its relationship with plant response to wounding. Arabidopsis cytochrome P450 enzymes in the CYP94 clade metabolize jasmonoyl-L-isoleucine (JA-Ile), a major metabolite of JA responsible for many biological effects attributed to the JA signaling pathway; thus, CYP94s are expected to contribute to the attenuation of JA-Ile-dependent wound responses. To directly test this, we created the double and triple knock-out mutants of three CYP94 genes, CYP94B1, CYP94B3, and CYP94C1. The mutations blocked the oxidation steps and caused JA-Ile to accumulate 3-4-fold the WT levels in the wounded leaves. Surprisingly, over accumulation of JA-Ile did not lead to a stronger wound response. On the contrary, the mutants displayed a series of symptoms reminiscent of JA-Ile deficiency, including resistance to wound-induced growth inhibition, decreased anthocyanin and trichomes, and increased susceptibility to insects. The mutants, however, responded normally to exogenous JA treatments, indicating that JA perception or signaling pathways were intact. Untargeted metabolite analyses revealed >40% reduction in wound-inducible metabolites in the mutants. These observations raise questions about the current JA signaling model and point toward a more complex model perhaps involving JA derivatives and/or feedback mechanisms. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
authors.affiliation: Division of Plant Sciences, University of Missouri, Columbia, MO, 65211, USA; Interdisciplinary Plant Group, University of Missouri, Columbia, MO, 65211, USA. Electronic address: ap9q2@mail.missouri.edu.
authors.forename: Arati N
authors.initials: AN
authors.lastname: Poudel
authors.affiliation: Division of Biochemistry, University of Missouri, Columbia, MO, 65211, USA; Interdisciplinary Plant Group, University of Missouri, Columbia, MO, 65211, USA. Electronic address: zhangtongzju@gmail.com.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Division of Plant Sciences, University of Missouri, Columbia, MO, 65211, USA. Electronic address: kwasniewskim@missouri.edu.
authors.forename: Misha
authors.initials: M
authors.lastname: Kwasniewski
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan. Electronic address: ryo.nakabayashi@riken.jp.
authors.forename: Ryo
authors.initials: R
authors.lastname: Nakabayashi
authors.affiliation: RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan; Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan. Electronic address: kazuki.saito@riken.jp.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
authors.affiliation: Division of Biochemistry, University of Missouri, Columbia, MO, 65211, USA; Interdisciplinary Plant Group, University of Missouri, Columbia, MO, 65211, USA. Electronic address: kooaj@missouri.edu.
authors.forename: Abraham J
authors.initials: AJ
authors.lastname: Koo
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D003517:Cyclopentanes / Q000008:administration & dosage / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006867:Hydrolases / Q000235:genetics* / Q000378:metabolism; D007532:Isoleucine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010084:Oxidation-Reduction; D054883:Oxylipins / Q000008:administration & dosage / Q000378:metabolism; D030821:Plants, Genetically Modified; D015398:Signal Transduction / Q000235:genetics
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; C532883:jasmonoyl-isoleucine; D007532:Isoleucine; C011006:jasmonic acid; D003577:Cytochrome P-450 Enzyme System; C104673:isoleucine hydroxylase; D006867:Hydrolases
keywords: hormone metabolism; jasmonate; oxylipin; plant signaling; wound response