title: The allene oxide cyclase of barley (Hordeum vulgare L.)--cloning and organ-specific expression.
abstract: The naturally occurring enantiomer of the various octadecanoids and jasmonates is established in a biosynthetic step catalyzed by the allene oxide cyclase (AOC). The AOC converts an allene oxide formed by an allene oxide synthase (AOS). Here, we show cloning and characterization of cDNAs encoding the AOC and a third AOS, respectively, in addition to the two AOSs previously published (Plant J. 21, 199-213, 2000). The ORF of the AOC-cDNA of 717 bp codes for a protein of 238 amino acid residues carrying a putative chloroplast target sequence. Overexpression without chloroplast target sequence revealed AOC activity. The AOC was found to be a single copy gene which mapped on chromosome 6H. AOC mRNA accumulation appeared in leaf segments upon treatment with various jasmonates, octadecanoids and ABA or during stress such as treatment with sorbitol or glucose solutions. Infection with powdery mildew activated AOC expression in susceptible and resistant lines of barley which correlated with PR1b expression. Among different tissues of barley seedlings, the scutellar node and leaf base accumulated AOC mRNA preferentially which correlated with accumulation of mRNAs for other biosynthetic enzymes (lipoxygenases, AOSs). AOC mRNA accumulation appeared also abundantly in parts of the root containing the tip and correlated with elevated levels of jasmonates. The data suggest a link of AOC expression and JA formation and support role of JA in stress responses and development of barley.
authors.affiliation: Institute of Plant Science and Crop Research, Corrensstrasse 3, D-06466 Gatersleben, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Maucher
authors.forename: Irene
authors.initials: I
authors.lastname: Stenzel
authors.forename: Otto
authors.initials: O
authors.lastname: Miersch
authors.forename: Niels
authors.initials: N
authors.lastname: Stein
authors.forename: Manoj
authors.initials: M
authors.lastname: Prasad
authors.forename: Uwe
authors.initials: U
authors.lastname: Zierold
authors.forename: Patrick
authors.initials: P
authors.lastname: Schweizer
authors.forename: Conrad
authors.initials: C
authors.lastname: Dorer
authors.forename: Bettina
authors.initials: B
authors.lastname: Hause
authors.forename: Claus
authors.initials: C
authors.lastname: Wasternack
mesh_terms: D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003517:Cyclopentanes / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism; D015870:Gene Expression; D018745:Genome, Plant; D001467:Hordeum / Q000201:enzymology* / Q000235:genetics; D019746:Intramolecular Oxidoreductases / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D007527:Isoenzymes; D008084:Lipoxygenase / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D054883:Oxylipins; D018514:Plant Structures / Q000201:enzymology; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014018:Tissue Distribution
chemical_list: D003517:Cyclopentanes; D018744:DNA, Plant; D005231:Fatty Acids, Unsaturated; D007527:Isoenzymes; D054883:Oxylipins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C025999:12-oxophytodienoic acid; C011006:jasmonic acid; D008084:Lipoxygenase; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase