Analysis of resistance gene-mediated defense responses in Arabidopsis thaliana plants carrying a mutation in CPR5

• Published in: Molecular plant-microbe interactions Vol. 11; no. 12; pp. 1196 - 1206
• Main Authors: Boch, J, Verbsky, M.L, Robertson, T.L, Larkin, J.C, Kunkel, B.N
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01-12-1998; The American Phytopathological Society
• Subjects: Agronomy. Soil science and plant productions; Arabidopsis thaliana; biochemical pathways; Biological and medical sciences; biological resistance; defense mechanisms; disease lesion mimic; disease resistance; Fundamental and applied biological sciences. Psychology; genes; genetic regulation; genetic resistance; Genetics and breeding of economic plants; gl3; lesions; loci; mutation; necrosis; pathogenesis-related proteins; Pest resistance; Plant pathogens; Pseudomonas syringae; Pseudomonas syringae pv. maculicola; Pseudomonas syringae pv. tomato; screening; systemic acquired resistance (SAR); trichomes; Varietal selection. Specialized plant breeding, plant breeding aims; Pseudomonadales; Plant pathogen; Regulator gene; Host agent relation; Induced resistance; Arabidopsis thaliana; Signal transduction; Regulation(control); Cruciferae; Pseudomonas syringae; Dicotyledones; Angiospermae; Bacteria; Pseudomonadaceae; Defense mechanism; Spermatophyta; Experimental plant
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/mpmi.1998.11.12.1196

In resistant plants, pathogen attack often leads to rapid activation of defense responses that limit multiplication and spread of the pathogen. To investigate the signaling mechanisms underlying this process, we carried out a screen for mutants in the signaling pathway governing resistance in Arabidopsis thaliana to the bacterial pathogen Pseudomonas syringae. This involved screening for suppressor mutations that restored resistance to a susceptible line carrying a mutation in the RPS2 resistance gene. A mutant that conferred resistance by activating defense responses in the absence of pathogens was isolated. This mutant, which carries a mutation at the CPR5 locus and was thus designated cpr5-2, exhibited resistance to P. syringae, spontaneous development of necrotic lesions, elevated PR gene expression in the absence of pathogens, and abnormal trichomes. Resistance gene-mediated defenses, including the hypersensitive response, restriction of pathogen growth, and induction of defense-related gene expression, were functional in cpr5-2 mutant plants. Additionally, in cpr5-2 plants RPS2-mediated induction of PR-1 expression was enhanced, whereas RPM1- mediated induction of ELI3 was not. These findings suggest that CPR5 encodes a negative regulator of the RPS2 signal transduction pathway.