title: Coordinated activation of metabolic pathways for antioxidants and defence compounds by jasmonates and their roles in stress tolerance in Arabidopsis.
abstract: Jasmonic acid (JA) and methyl jasmonate (MeJA), collectively termed jasmonates, are ubiquitous plant signalling compounds. Several types of stress conditions, such as wounding and pathogen infection, cause endogenous JA accumulation and the expression of jasmonate-responsive genes. Although jasmonates are important signalling components for the stress response in plants, the mechanism by which jasmonate signalling contributes to stress tolerance has not been clearly defined. A comprehensive analysis of jasmonate-regulated metabolic pathways in Arabidopsis was performed using cDNA macroarrays containing 13516 expressed sequence tags (ESTs) covering 8384 loci. The results showed that jasmonates activate the coordinated gene expression of factors involved in nine metabolic pathways belonging to two functionally related groups: (i) ascorbate and glutathione metabolic pathways, which are important in defence responses to oxidative stress, and (ii) biosynthesis of indole glucosinolate, which is a defence compound occurring in the Brassicaceae family. We confirmed that JA induces the accumulation of ascorbate, glutathione and cysteine and increases the activity of dehydroascorbate reductase, an enzyme in the ascorbate recycling pathway. These antioxidant metabolic pathways are known to be activated under oxidative stress conditions. Ozone (O3) exposure, a representative oxidative stress, is known to cause activation of antioxidant metabolism. We showed that O3 exposure caused the induction of several genes involved in antioxidant metabolism in the wild type. However, in jasmonate-deficient Arabidopsis 12-oxophytodienoate reductase 3 (opr3) mutants, the induction of antioxidant genes was abolished. Compared with the wild type, opr3 mutants were more sensitive to O3 exposure. These results suggest that the coordinated activation of the metabolic pathways mediated by jasmonates provides resistance to environmental stresses.
authors.affiliation: Tokyo Institute of Technology, Graduate School of Bioscience and Biotechnology, Yokohama, Kanagawa, 226-8501, Japan. ysasaki@bio.titech.ac.jp
authors.forename: Yuko
authors.initials: Y
authors.lastname: Sasaki-Sekimoto
authors.forename: Nozomi
authors.initials: N
authors.lastname: Taki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Obayashi
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Aono
authors.forename: Fuminori
authors.initials: F
authors.lastname: Matsumoto
authors.forename: Nozomu
authors.initials: N
authors.lastname: Sakurai
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Masami Yokota
authors.initials: MY
authors.lastname: Hirai
authors.forename: Masaaki
authors.initials: M
authors.lastname: Noji
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
authors.forename: Tatsuru
authors.initials: T
authors.lastname: Masuda
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Takamiya
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shibata
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohta
mesh_terms: D000085:Acetates / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism*; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D005961:Glucosinolates / Q000378:metabolism; D007211:Indoles / Q000378:metabolism; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D054883:Oxylipins; D010126:Ozone / Q000633:toxicity; D013455:Sulfur / Q000378:metabolism
chemical_list: D000085:Acetates; D000975:Antioxidants; D003517:Cyclopentanes; D018744:DNA, Plant; D005961:Glucosinolates; D007211:Indoles; D054883:Oxylipins; D010126:Ozone; C011006:jasmonic acid; D013455:Sulfur; C072239:methyl jasmonate; D001205:Ascorbic Acid