title: Global analysis of Arabidopsis/downy mildew interactions reveals prevalence of incomplete resistance and rapid evolution of pathogen recognition.
abstract: Interactions between Arabidopsis thaliana and its native obligate oomycete pathogen Hyaloperonospora arabidopsidis (Hpa) represent a model system to study evolution of natural variation in a host/pathogen interaction. Both Arabidopsis and Hpa genomes are sequenced and collections of different sub-species are available. We analyzed ∼400 interactions between different Arabidopsis accessions and five strains of Hpa. We examined the pathogen's overall ability to reproduce on a given host, and performed detailed cytological staining to assay for pathogen growth and hypersensitive cell death response in the host. We demonstrate that intermediate levels of resistance are prevalent among Arabidopsis populations and correlate strongly with host developmental stage. In addition to looking at plant responses to challenge by whole pathogen inoculations, we investigated the Arabidopsis resistance attributed to recognition of the individual Hpa effectors, ATR1 and ATR13. Our results suggest that recognition of these effectors is evolutionarily dynamic and does not form a single clade in overall Arabidopsis phylogeny for either effector. Furthermore, we show that the ultimate outcome of the interactions can be modified by the pathogen, despite a defined gene-for-gene resistance in the host. These data indicate that the outcome of disease and disease resistance depends on genome-for-genome interactions between the host and its pathogen, rather than single gene pairs as thought previously.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America.
authors.forename: Ksenia V
authors.initials: KV
authors.lastname: Krasileva
authors.forename: Connie
authors.initials: C
authors.lastname: Zheng
authors.forename: Lauriebeth
authors.initials: L
authors.lastname: Leonelli
authors.forename: Sandra
authors.initials: S
authors.lastname: Goritschnig
authors.forename: Douglas
authors.initials: D
authors.lastname: Dahlbeck
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Staskawicz
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D005075:Biological Evolution; D018548:Cotyledon / Q000382:microbiology; D060467:Disease Resistance / Q000276:immunology*; D060146:Ecotype; D054884:Host-Pathogen Interactions; D044742:Peronospora / Q000254:growth & development / Q000502:physiology*; D010641:Phenotype; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D020598:Proto-Oncogene Proteins c-myb / Q000378:metabolism; D013045:Species Specificity; D013170:Spores / Q000502:physiology; D013194:Staining and Labeling
chemical_list: C511988:ATR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D020598:Proto-Oncogene Proteins c-myb