title: Cytochrome P450 CYP94B3 mediates catabolism and inactivation of the plant hormone jasmonoyl-L-isoleucine.
abstract: The phytohormone jasmonoyl-L-isoleucine (JA-Ile) signals through the COI1-JAZ coreceptor complex to control key aspects of plant growth, development, and immune function. Despite detailed knowledge of the JA-Ile biosynthetic pathway, little is known about the genetic basis of JA-Ile catabolism and inactivation. Here, we report the identification of a wound- and jasmonate-responsive gene from Arabidopsis that encodes a cytochrome P450 (CYP94B3) involved in JA-Ile turnover. Metabolite analysis of wounded leaves showed that loss of CYP94B3 function in cyp94b3 mutants causes hyperaccumulation of JA-Ile and concomitant reduction in 12-hydroxy-JA-Ile (12OH-JA-Ile) content, whereas overexpression of this enzyme results in severe depletion of JA-Ile and corresponding changes in 12OH-JA-Ile levels. In vitro studies showed that heterologously expressed CYP94B3 converts JA-Ile to 12OH-JA-Ile, and that 12OH-JA-Ile is less effective than JA-Ile in promoting the formation of COI1-JAZ receptor complexes. CYP94B3-overexpressing plants displayed phenotypes indicative of JA-Ile deficiency, including defects in male fertility, resistance to jasmonate-induced growth inhibition, and susceptibility to insect attack. Increased accumulation of JA-Ile in wounded cyp94b3 leaves was associated with enhanced expression of jasmonate-responsive genes. These results demonstrate that CYP94B3 exerts negative feedback control on JA-Ile levels and performs a key role in attenuation of jasmonate responses.
authors.affiliation: Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Abraham J K
authors.initials: AJ
authors.lastname: Koo
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Cooke
authors.forename: Gregg A
authors.initials: GA
authors.lastname: Howe
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D007532:Isoleucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008660:Metabolism; D006899:Mixed Function Oxygenases / Q000378:metabolism; D008957:Models, Genetic; D054883:Oxylipins / Q000378:metabolism; D010641:Phenotype; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D015398:Signal Transduction; D018411:Spodoptera
chemical_list: D003517:Cyclopentanes; D005227:Fatty Acids; D054883:Oxylipins; D010937:Plant Growth Regulators; D010940:Plant Proteins; C532883:jasmonoyl-isoleucine; D007532:Isoleucine; C011006:jasmonic acid; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C560423:cytochrome P-450 94B3, Arabidopsis