Downy mildew (Peronospora parasitica) resistance genes in Arabidopsis vary in functional requirements for NDR1, EDS1, NPR1 and salicylic acid accumulation

• Published in: The Plant journal : for cell and molecular biology Vol. 22; no. 6; pp. 523 - 529
• Main Authors: McDowell, John M., Cuzick, Alayne, Can, Canan, Beynon, Jim, Dangl, Jeffery L., Holub, Eric B.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.06.2000; Blackwell Science
• Subjects: Agronomy. Soil science and plant productions; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins; Arabidopsis thaliana; Biological and medical sciences; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; EDS1 gene; Fundamental and applied biological sciences. Psychology; Fungal Proteins - genetics; Fungal Proteins - metabolism; Genetics and breeding of economic plants; jasmonic acid; Mutagenesis; NDR1 gene; NPR1 gene; Oomycetes - pathogenicity; Peronospora parasitica; Pest resistance; Plant Diseases - genetics; Plant pathogens; Plants, Genetically Modified; Protein Kinases; RPP7 gene; RPP8 gene; Saccharomyces cerevisiae Proteins; salicylic acid; Salicylic Acid - metabolism; Signal Transduction; Transcription Factors - genetics; Transcription Factors - metabolism; Varietal selection. Specialized plant breeding, plant breeding aims; Salicylic acid; Plant pathogen; Phycomycetes; Fungi; Arabidopsis thaliana; Signal transduction; Disease resistance; Microorganism resistance; Sensitivity resistance; Gene; Cruciferae; Dicotyledones; Angiospermae; Defense mechanism; Spermatophyta; Mutation; Experimental plant; Biological accumulation; Peronospora parasitica; Thallophyta
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313x.2000.00771.x

Summary To better understand the genetic requirements for R gene‐dependent defense activation in Arabidopsis, we tested the effect of several defense response mutants on resistance specified by eight RPP genes (for resistance to Peronospora parasitica) expressed in the Col‐0 background. In most cases, resistance was not suppressed by a mutation in the SAR regulatory gene NPR1 or by expression of the NahG transgene. Thus, salicylic acid accumulation and NPR1 function are not necessary for resistance mediated by these RPP genes. In addition, resistance conferred by two of these genes, RPP7 and RPP8, was not significantly suppressed by mutations in either EDS1 or NDR1. RPP7 resistance was also not compromised by mutations in EIN2, JAR1 or COI1 which affect ethylene or jasmonic acid signaling. Double mutants were therefore tested. RPP7 and RPP8 were weakly suppressed in an eds1‐2/ndr1‐1 background, suggesting that these RPP genes operate additively through EDS1, NDR1 and as‐yet‐undefined signaling components. RPP7 was not compromised in coi1/npr1 or coi1/NahG backgrounds. These observations suggest that RPP7 initiates resistance through a novel signaling pathway that functions independently of salicylic acid accumulation or jasmonic acid response components.