Characterization of eds1, a mutation in Arabidopsis suppressing resistance to Peronospora parasitica specified by several different RPP genes

• Published in: The Plant cell Vol. 8; no. 11; pp. 2033 - 2046
• Main Authors: Parker, J.E. (Norwich Research Park, Norwich, United Kingdom.), Holub, E.B, Frost, L.N, Falk, A, Gunn, N.D, Daniels, M.J
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Physiologists 01-11-1996
• Subjects: ALBUGO; Arabidopsis - genetics; Arabidopsis - immunology; ARABIDOPSIS THALIANA; BRASSICA OLERACEA; BREMIA LACTUCAE; CARTE GENETIQUE; Chromosomes; COTILEDONES; COTYLEDON; Disease resistance; ESPORULACION; FENOTIPOS; Fungi - pathogenicity; GENE; GENE RECESSIF; GENES; GENES RECESIVOS; Genes, Plant; Genetic loci; Genetic mutation; GENETICA; GENETIQUE; Inoculation; LOCI; LOCUS; MAPAS GENETICOS; MUTACION; MUTATION; Parasitism; Pathogens; PERONOSPORA PARASITICA; PHENOTYPE; Plant cells; Plant Diseases - genetics; Plant Proteins - genetics; PLANTAS; PLANTE; Plants; PSEUDOMONAS SYRINGAE; RACE PHYSIOLOGIQUE; RAZAS FISIOLOGICAS; RESISTANCE AUX MALADIES; RESISTENCIA A LA ENFERMEDAD; Seedlings; SEGREGACION; SEGREGATION; SPORULATION
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.8.11.2033

The interaction between Arabidopsis and the biotrophic oomycete Peronospora parasitica (downy mildew) provides an attractive model pathosystem to identify molecular components of the host that are required for genotype-specific recognition of the parasite. These components are the so-called RPP genes (for resistance to P. parasitica). Mutational analysis of the ecotype Wassilewskija (Ws-0) revealed an RPP-nonspecific locus called EDS1 (for enhanced disease susceptibility) that is required for the function of RPP genes on chromosomes 3 (RPP1/RPP14 and RPP10) and 4 (RPP12). Genetic analyses demonstrated that the eds1 mutation is recessive and is not a defective allele of any known RPP gene, mapping to the bottom arm of chromosome 3 (approximately 13 centimorgans below RPP1/RPP14). Phenotypically, the Ws-eds1 mutant seedlings supported heavy sporulation by P. parasitica isolates that are each diagnostic for one of the RPP genes in wild-type Ws-0; none of the isolates is capable of sporulating on wild-type Ws-0. Ws-eds1 seedlings exhibited enhanced susceptibility to some P. parasitica isolates when compared with a compatible wild-type ecotype, Columbia, and the eds1 parental ecotype, Ws-0. This was observed as earlier initiation of sporulation and elevated production of conidiosporangia. Surprisingly, cotyledons of Ws-eds1 also supported low sporulation by five isolates of P. parasitica from Brassica oleracea. These isolates were unable to sporulate on 100 ecotypes of Arabidopsis, including wild-type Ws-0. An isolate of Albugo candida (white blister) from B. oleracea also sporulated on Ws-eds1, but the mutant exhibited no alteration in phenotype when inoculated with several oomycete isolates from other host species The bacterial resistance gene RPM1, conferring specific recognition of the avirulence gene avrB from Pseudomonas syringae pv glycinea, was not compromised in Ws-eds1 plants. The mutant also retained full responsiveness to the chemical inducer of systemic acq