title: Defense and resistance-inducing activities in tobacco of the sulfated beta-1,3 glucan PS3 and its synergistic activities with the unsulfated molecule.
abstract: Laminarin, a beta-1,3 glucan with single beta-glucose branches at position 6, was chemically sulfated to produce PS3 with a degree of sulfation of 2.4. PS3 has previously been shown to activate the salicylic acid (SA) signaling pathway in infiltrated tobacco and Arabidopsis thaliana leaf tissues. Here, we investigated whether PS3 induces systemic defense and resistance responses in tobacco. Using a radiolabeled compound, it was first demonstrated that PS3 remains strictly localized to the infiltrated tissues. PS3 is also resistant to beta-glucanase degradation. In transgenic PR1-beta-glucuronidase (GUS) tobacco plants, PS3 causes a strong increase in GUS activity in treated tissues but none in untreated leaves. PS3-infiltrated tissues challenged with tobacco mosaic virus (TMV) 8 d after elicitor application show a decrease in both the lesion number and the lesion size, whereas treatment with laminarin, the unsulfated native glucan, affected only the lesion number. PS3 does not induce systemic acquired resistance to TMV. PS3 and laminarin show synergistic effects in promoting the oxidative burst in tobacco cell suspensions and in increasing the expression of genes encoding O-methyltransferases of the phenylpropanoid pathway in tobacco plants. No synergistic effect was observed on the expression of either the SA-dependent acidic PR1 gene or the ethylene-dependent basic PR5 gene in tobacco plants.
authors.affiliation: Institut de Biologie Moléculaire des Plantes du CNRS, Université Louis Pasteur, 12 rue du Général Zimmer, 67084 Strasbourg, France.
authors.forename: Rozenn
authors.initials: R
authors.lastname: Ménard
authors.forename: Patrice
authors.initials: P
authors.lastname: de Ruffray
authors.forename: Bernard
authors.initials: B
authors.lastname: Fritig
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Yvin
authors.forename: Serge
authors.initials: S
authors.lastname: Kauffmann
mesh_terms: D002478:Cells, Cultured; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D004693:Glucan Endo-1,3-beta-D-Glucosidase / Q000502:physiology; D005936:Glucans / Q000502:physiology*; D005966:Glucuronidase / Q000032:analysis / Q000502:physiology; D008780:Methyltransferases / Q000235:genetics / Q000502:physiology; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000737:chemistry / Q000502:physiology; D010940:Plant Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D011134:Polysaccharides / Q000502:physiology; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000502:physiology; D016897:Respiratory Burst; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014026:Nicotiana / Q000737:chemistry / Q000235:genetics / Q000502:physiology* / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000472:pathogenicity*; D047071:beta-Glucans
chemical_list: D005936:Glucans; D010940:Plant Proteins; D011134:Polysaccharides; D047071:beta-Glucans; C053376:pathogenesis-related proteins, plant; C008247:laminaran; C033363:beta-1,3-glucan; D008780:Methyltransferases; D005966:Glucuronidase; D004693:Glucan Endo-1,3-beta-D-Glucosidase