title: An Arabidopsis callose synthase.
abstract: Beta-1,3-glucan polymers are major structural components of fungal cell walls, while cellulosic beta-1,4-glucan is the predominant polysaccharide in plant cell walls. Plant beta-1,3-glucan, called callose, is produced in pollen and in response to pathogen attack and wounding, but it has been unclear whether callose synthases can also produce cellulose and whether plant cellulose synthases may also produce beta-1,3-glucans. We describe here an Arabidopsis gene, AtGsl5, encoding a plasma membrane-localized protein homologous to yeast beta-1,3-glucan synthase whose expression partially complements a yeast beta-1,3-glucan synthase mutant. AtGsl5 is developmentally expressed at highest levels in flowers, consistent with flowers having high beta-1,3-glucan synthase activities for deposition of callose in pollen. A role for AtGsl5 in callose synthesis is also indicated by AtGsl5 expression in the Arabidopsis mpk4 mutant which exhibits systemic acquired resistance (SAR), elevated beta-1,3-glucan synthase activity, and increased callose levels. In addition, AtGsl5 is a likely target of salicylic acid (SA)-dependent SAR, since AtGsl5 mRNA accumulation is induced by SA in wild-type plants, while expression of the nahG salicylate hydroxylase reduces AtGsl5 mRNA levels in the mpk4 mutant. These results indicate that AtGsl5 is likely involved in callose synthesis in flowering tissues and in the mpk4 mutant.
authors.affiliation: Department of Plant Physiology, Institute of Molecular Biology, University of Copenhagen, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Ostergaard
authors.forename: Morten
authors.initials: M
authors.lastname: Petersen
authors.forename: Ole
authors.initials: O
authors.lastname: Mattsson
authors.forename: John
authors.initials: J
authors.lastname: Mundy
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D015152:Blotting, Northern; D054714:Echinocandins; D005656:Fungal Proteins / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005816:Genetic Complementation Test; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D020156:Salicylic Acid / Q000494:pharmacology; D029702:Schizosaccharomyces pombe Proteins
chemical_list: D054714:Echinocandins; D005656:Fungal Proteins; D008565:Membrane Proteins; D018749:RNA, Plant; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D005964:Glucosyltransferases; C020570:1,3-beta-glucan synthase; C091618:FKS1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D020156:Salicylic Acid