title: Evidence supporting a role of jasmonic acid in Arabidopsis leaf senescence.
abstract: In this work, the role of jasmonic acid (JA) in leaf senescence is examined. Exogenous application of JA caused premature senescence in attached and detached leaves in wild-type Arabidopsis but failed to induce precocious senescence of JA-insensitive mutant coi1 plants, suggesting that the JA-signaling pathway is required for JA to promote leaf senescence. JA levels in senescing leaves are 4-fold higher than in non-senescing ones. Concurrent with the increase in JA level in senescing leaves, genes encoding the enzymes that catalyze most of the reactions of the JA biosynthetic pathway are differentially activated during leaf senescence in Arabidopsis, except for allene oxide synthase, which is constitutively and highly expressed throughout leaf development. Arabidopsis lipoxygenase 1 (cytoplasmic) expression is greatly increased but lipoxygenase 2 (plastidial) expression is sharply reduced during leaf senescence. Similarly, AOC1 (allene oxide cyclase 1), AOC2, and AOC3 are all up-regulated, whereas AOC4 is down-regulated with the progression of leaf senescence. The transcript levels of 12-oxo-PDA reductase 1 and 12-oxo-PDA reductase 3 also increase in senescing leaves, as does PED1 (encoding a 3-keto-acyl-thiolase for beta-oxidation). This represents the first report, to our knowledge, of an increase in JA levels and expression of oxylipin genes during leaf senescence, and indicates that JA may play a role in the senescence program.
authors.affiliation: Plant Physiology/Biochemistry/Molecular Biology Program, Department of Agronomy, Agricultural Sciences Center-North, University of Kentucky, Lexington, Kentucky 40546-0091, USA.
authors.forename: Yuehui
authors.initials: Y
authors.lastname: He
authors.forename: Hirotada
authors.initials: H
authors.lastname: Fukushige
authors.forename: David F
authors.initials: DF
authors.lastname: Hildebrand
authors.forename: Susheng
authors.initials: S
authors.lastname: Gan
mesh_terms: D000101:Acetyl-CoA C-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism* / Q000494:pharmacology; D023082:Defensins; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D019746:Intramolecular Oxidoreductases / Q000235:genetics / Q000378:metabolism; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D044925:Oxidoreductases Acting on CH-CH Group Donors; D054883:Oxylipins; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D003517:Cyclopentanes; D023082:Defensins; D005231:Fatty Acids, Unsaturated; D054883:Oxylipins; D010940:Plant Proteins; D002734:Chlorophyll; C025999:12-oxophytodienoic acid; C011006:jasmonic acid; D010088:Oxidoreductases; D008084:Lipoxygenase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C106360:12-oxophytodienoate reductase; D000101:Acetyl-CoA C-Acetyltransferase; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase