title: Uncoupling PR gene expression from NPR1 and bacterial resistance: characterization of the dominant Arabidopsis cpr6-1 mutant.
abstract: In Arabidopsis, NPR1 mediates the salicylic acid (SA)-induced expression of pathogenesis-related (PR) genes and systemic acquired resistance (SAR). Here, we report the identification of another component, CPR 6, that may function with NPR1 in regulating PR gene expression. The dominant CPR 6-1 mutant expresses the SA/NPR1-regulated PR genes (PR-1, BGL 2, and PR-5) and displays enhanced resistance to Pseudomonas syringae pv maculicola ES4326 and Peronospora parasitica Noco2 in the absence of SAR induction. cpr 6-1-induced PR gene expression is not suppressed in the cpr 6-1 npr1-1 double mutant but is suppressed when SA is removed by salicylate hydroxylase. Thus, constitutive PR gene expression in cpr 6-1 requires SA but not NPR1. In addition, resistance to P. s. maculicola ES4326 is suppressed in the cpr 6-1 npr1-1 double mutant, despite expression of PR-1, BGL 2, and PR-5. Resistance to P. s. maculicola ES4326 must therefore be accomplished through unidentified antibacterial gene products that are regulated through NPR1. These results show that CPR 6 is an important regulator of multiple signal transduction pathways involved in plant defense.
authors.affiliation: Developmental, Cell, and Molecular Biology Group, Department of Botany, Box 91000, Duke University, Durham, North Carolina 27708-1000, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Clarke
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: D F
authors.initials: DF
authors.lastname: Klessig
authors.forename: X
authors.initials: X
authors.lastname: Dong
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000382:microbiology* / Q000502:physiology; D029681:Arabidopsis Proteins; D002352:Carrier Proteins / Q000235:genetics*; D000081406:Peptidyl-Prolyl Isomerase F; D021983:Cyclophilins; D004843:Epistasis, Genetic; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005799:Genes, Dominant; D017343:Genes, Plant; D009154:Mutation; D009868:Oomycetes / Q000472:pathogenicity; D019696:Peptidylprolyl Isomerase / Q000235:genetics*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics*; D011549:Pseudomonas / Q000472:pathogenicity; D012459:Salicylates / Q000378:metabolism; D020156:Salicylic Acid
chemical_list: D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D000081406:Peptidyl-Prolyl Isomerase F; C105496:NPR1 protein, Arabidopsis; D010940:Plant Proteins; D012459:Salicylates; C053376:pathogenesis-related proteins, plant; D021983:Cyclophilins; D019696:Peptidylprolyl Isomerase; D020156:Salicylic Acid