title: Ascorbate deficiency influences the leaf cell wall glycoproteome in Arabidopsis thaliana.
abstract: The cell wall forms the first line of interaction between the plant and the external environment. Based on the observation that ascorbate-deficient vtc mutants of Arabidopsis thaliana have increased cell wall peroxidase activity, the cell wall glycoproteome of vtc2-2 was investigated. Glycoproteins were purified from fully expanded leaves by Concanavalin A affinity chromatography and analysed by liquid chromatography quadrupole time-of-flight mass spectrometry. This procedure identified 63 proteins with predicted glycosylation sites and cell wall localization. Of these, 11 proteins were differentially expressed between vtc2-2 and wild type. In particular, PRX33/34 were identified as contributing to increased peroxidase activity in response to ascorbate deficiency. This is the same peroxidase previously shown to contribute to hydrogen peroxide generation and pathogen resistance. Three fasciclin-like arabinogalactan proteins (FLA1, 2 and 8) had lower abundance in vtc2-2. Inspection of published microarray data shows that these also have lower gene expression in vtc1 and vtc2-1 and are decreased in expression by pathogen challenge and oxidative stresses. Ascorbate deficiency therefore impacts expression of cell wall proteins involved in pathogen responses and these presumably contribute to the increased resistance of vtc mutants to biotrophic pathogens.
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK.
authors.forename: Nighat
authors.initials: N
authors.lastname: Sultana
authors.forename: Hannah V
authors.initials: HV
authors.lastname: Florance
authors.forename: Alex
authors.initials: A
authors.lastname: Johns
authors.forename: Nicholas
authors.initials: N
authors.lastname: Smirnoff
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism* / Q000528:radiation effects; D006023:Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D006909:Hydroxyproline / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D018515:Plant Leaves / Q000166:cytology* / Q000378:metabolism* / Q000528:radiation effects; D021381:Protein Transport / Q000528:radiation effects; D020543:Proteome / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment; D013347:Subcellular Fractions / Q000378:metabolism / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; D006023:Glycoproteins; D010455:Peptides; D020543:Proteome; D010544:Peroxidases; D001205:Ascorbic Acid; D006909:Hydroxyproline
keywords: Arabinogalactan; cell wall proteome; glycoproteins; hydrogen peroxide; pathogen response; peroxidase; reactive oxygen; vitamin C; vtc mutants