title: Arabidopsis CYP86A2 represses Pseudomonas syringae type III genes and is required for cuticle development.
abstract: Pseudomonas syringae relies on type III secretion system to deliver effector proteins into the host cell for parasitism. Type III genes are induced in planta, but host factors affecting the induction are poorly understood. Here we report on the identification of an Arabidopsis mutant, att1 (for aberrant induction of type three genes), that greatly enhances the expression of bacterial type III genes avrPto and hrpL. att1 plants display enhanced disease severity to a virulent strain of P. syringae, suggesting a role of ATT1 in disease resistance. ATT1 encodes CYP86A2, a cytochrome P450 monooxygenase catalyzing fatty acid oxidation. The cutin content is reduced to 30% in att1, indicating that CYP86A2 plays a major role in the biosynthesis of extracellular lipids. att1 has a loose cuticle membrane ultrastructure and shows increased permeability to water vapor, demonstrating the importance of the cuticle membrane in controlling water loss. The enhanced avrPto-luc expression is specific to att1, but not another cuticle mutant, wax2. The results suggest that certain cutin-related fatty acids synthesized by CYP86A2 may repress bacterial type III gene expression in the intercellular spaces.
authors.affiliation: Department of Plant Pathology, Kansas State University, Manhattan, KS, USA.
authors.forename: Fangming
authors.initials: F
authors.lastname: Xiao
authors.forename: S Mark
authors.initials: SM
authors.lastname: Goodwin
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Xiao
authors.forename: Zhaoyu
authors.initials: Z
authors.lastname: Sun
authors.forename: Douglas
authors.initials: D
authors.lastname: Baker
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Tang
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Jenks
authors.forename: Jian-Min
authors.initials: JM
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000382:microbiology; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D017343:Genes, Plant; D008563:Membrane Lipids / Q000032:analysis; D008969:Molecular Sequence Data; D009154:Mutation; D018515:Plant Leaves / Q000648:ultrastructure; D018547:Plant Stems / Q000254:growth & development* / Q000648:ultrastructure; D044224:Pseudomonas syringae / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
chemical_list: D008563:Membrane Lipids; C000521:cutin; D003577:Cytochrome P-450 Enzyme System