title: Loss of a callose synthase results in salicylic acid-dependent disease resistance.
abstract: Plants attacked by pathogens rapidly deposit callose, a beta-1,3-glucan, at wound sites. Traditionally, this deposition is thought to reinforce the cell wall and is regarded as a defense response. Surprisingly, here we found that powdery mildew resistant 4 (pmr4), a mutant lacking pathogen-induced callose, became resistant to pathogens, rather than more susceptible. This resistance was due to mutation of a callose synthase, resulting in a loss of the induced callose response. Double-mutant analysis indicated that blocking the salicylic acid (SA) defense signaling pathway was sufficient to restore susceptibility to pmr4 mutants. Thus, callose or callose synthase negatively regulates the SA pathway.
authors.affiliation: Department of Plant Biology, Carnegie Institution, Stanford, CA 94305, USA.
authors.forename: Marc T
authors.initials: MT
authors.lastname: Nishimura
authors.forename: Monica
authors.initials: M
authors.lastname: Stein
authors.forename: Bi-Huei
authors.initials: BH
authors.lastname: Hou
authors.forename: John P
authors.initials: JP
authors.lastname: Vogel
authors.forename: Herb
authors.initials: H
authors.lastname: Edwards
authors.forename: Shauna C
authors.initials: SC
authors.lastname: Somerville
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D001203:Ascomycota / Q000502:physiology*; D016923:Cell Death; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005936:Glucans / Q000378:metabolism; D005964:Glucosyltransferases / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010935:Plant Diseases; D018515:Plant Leaves / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins; D015398:Signal Transduction
chemical_list: D005936:Glucans; D008565:Membrane Proteins; D029702:Schizosaccharomyces pombe Proteins; C048306:callose; D005964:Glucosyltransferases; C020570:1,3-beta-glucan synthase; D020156:Salicylic Acid