title: Myo-inositol oxygenase is important for the removal of excess myo-inositol from syncytia induced by Heterodera schachtii in Arabidopsis roots.
abstract: The enzyme myo-inositol oxygenase is the key enzyme of a pathway leading from myo-inositol to UDP-glucuronic acid. In Arabidopsis, myo-inositol oxygenase is encoded by four genes. All genes are strongly expressed in syncytia induced by the beet cyst nematode Heterodera schachtii in Arabidopsis roots. Here, we studied the effect of a quadruple myo-inositol oxygenase mutant on nematode development. We performed metabolite profiling of syncytia induced in roots of the myo-inositol oxygenase quadruple mutant. The role of galactinol in syncytia was studied using Arabidopsis lines with elevated galactinol levels and by supplying galactinol to wild-type seedlings. The quadruple myo-inositol oxygenase mutant showed a significant reduction in susceptibility to H. schachtii, and syncytia had elevated myo-inositol and galactinol levels and an elevated expression level of the antimicrobial thionin gene Thi2.1. This reduction in susceptibility could also be achieved by exogenous application of galactinol to wild-type seedlings. The primary function of myo-inositol oxygenase for syncytium development is probably not the production of UDP-glucuronic acid as a precursor for cell wall polysaccharides, but the reduction of myo-inositol levels and thereby a reduction in the galactinol level to avoid the induction of defence-related genes.
authors.affiliation: Division of Plant Protection, Department of Crop Sciences, University of Natural Resources and Life Sciences, A-1019, Vienna, Austria.
authors.forename: Shahid
authors.initials: S
authors.lastname: Siddique
authors.affiliation: Plant Physiology, University of Salzburg, Hellbrunnerstr. 34, A-5020, Salzburg, Austria.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Endres
authors.affiliation: Department of Botany, Warsaw University of Life Sciences (SGGW), 02-787, Warsaw, Poland.
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Sobczak
authors.affiliation: INRES, Department of Molecular Phytomedicine, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115, Bonn, Germany.
authors.forename: Zoran S
authors.initials: ZS
authors.lastname: Radakovic
authors.affiliation: Department of Molecular Systems Biology, University of Vienna, A-1090, Vienna, Austria.
authors.forename: Lena
authors.initials: L
authors.lastname: Fragner
authors.affiliation: INRES, Department of Molecular Phytomedicine, University of Bonn, Karlrobert-Kreiten-Str. 13, 53115, Bonn, Germany.
authors.forename: Florian M W
authors.initials: FMW
authors.lastname: Grundler
authors.affiliation: Department of Molecular Systems Biology, University of Vienna, A-1090, Vienna, Austria.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Weckwerth
authors.affiliation: Plant Physiology, University of Salzburg, Hellbrunnerstr. 34, A-5020, Salzburg, Austria.
authors.forename: Raimund
authors.initials: R
authors.lastname: Tenhaken
authors.affiliation: Division of Plant Protection, Department of Crop Sciences, University of Natural Resources and Life Sciences, A-1019, Vienna, Austria.
authors.forename: Holger
authors.initials: H
authors.lastname: Bohlmann
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000469:parasitology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007294:Inositol / Q000378:metabolism*; D050562:Inositol Oxygenase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009348:Nematoda / Q000502:physiology*; D018517:Plant Roots / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D007294:Inositol; D050562:Inositol Oxygenase
keywords: Arabidopsis; Heterodera schachtii; ascorbic acid; galactinol; myo-inositol oxygenase; roots; syncytium