title: Induction of jasmonate biosynthesis in arbuscular mycorrhizal barley roots.
abstract: Colonization of barley (Hordeum vulgare cv Salome) roots by an arbuscular mycorrhizal fungus, Glomus intraradices Schenck & Smith, leads to elevated levels of endogenous jasmonic acid (JA) and its amino acid conjugate JA-isoleucine, whereas the level of the JA precursor, oxophytodienoic acid, remains constant. The rise in jasmonates is accompanied by the expression of genes coding for an enzyme of JA biosynthesis (allene oxide synthase) and of a jasmonate-induced protein (JIP23). In situ hybridization and immunocytochemical analysis revealed that expression of these genes occurred cell specifically within arbuscule-containing root cortex cells. The concomitant gene expression indicates that jasmonates are generated and act within arbuscule-containing cells. By use of a near-synchronous mycorrhization, analysis of temporal expression patterns showed the occurrence of transcript accumulation 4 to 6 d after the appearance of the first arbuscules. This suggests that the endogenous rise in jasmonates might be related to the fully established symbiosis rather than to the recognition of interacting partners or to the onset of interaction. Because the plant supplies the fungus with carbohydrates, a model is proposed in which the induction of JA biosynthesis in colonized roots is linked to the stronger sink function of mycorrhizal roots compared with nonmycorrhizal roots.
authors.affiliation: Abteilung Sekundärstoffwechsel, Leibniz-Institut für Pflanzenbiochemie, D-06120 Halle, Saale, Germany. bhause@ipb-halle.de
authors.forename: Bettina
authors.initials: B
authors.lastname: Hause
authors.forename: Walter
authors.initials: W
authors.lastname: Maier
authors.forename: Otto
authors.initials: O
authors.lastname: Miersch
authors.forename: Robert
authors.initials: R
authors.lastname: Kramell
authors.forename: Dieter
authors.initials: D
authors.lastname: Strack
mesh_terms: D003517:Cyclopentanes / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D019746:Intramolecular Oxidoreductases / Q000235:genetics / Q000378:metabolism; D038821:Mycorrhizae / Q000254:growth & development*; D054883:Oxylipins; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D013559:Symbiosis
chemical_list: D003517:Cyclopentanes; D005231:Fatty Acids, Unsaturated; C109805:JIP23 protein, Hordeum vulgare; D054883:Oxylipins; D010940:Plant Proteins; D017382:Reactive Oxygen Species; C025999:12-oxophytodienoic acid; C011006:jasmonic acid; D019746:Intramolecular Oxidoreductases; C021377:hydroperoxide isomerase