title: Host-parasite coevolutionary conflict between Arabidopsis and downy mildew.
abstract: Plants are constantly exposed to attack by an array of diverse pathogens but lack a somatically adaptive immune system. In spite of this, natural plant populations do not often suffer destructive disease epidemics. Elucidating how allelic diversity within plant genes that function to detect pathogens (resistance genes) counteracts changing structures of pathogen genes required for host invasion (pathogenicity effectors) is critical to our understanding of the dynamics of natural plant populations. The RPP13 resistance gene is the most polymorphic gene analyzed to date in the model plant Arabidopsis thaliana. Here we report the cloning of the avirulence gene, ATR13, that triggers RPP13-mediated resistance, and we show that it too exhibits extreme levels of amino acid polymorphism. Evidence of diversifying selection visible in both components suggests that the host and pathogen may be locked in a coevolutionary conflict at these loci, where attempts to evade host resistance by the pathogen are matched by the development of new detection capabilities by the host.
authors.affiliation: Warwick, HRI University of Warwick, Wellesbourne, Warwick, CV35 9EF, UK.
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Allen
authors.forename: Peter D
authors.initials: PD
authors.lastname: Bittner-Eddy
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Grenville-Briggs
authors.forename: Julia C
authors.initials: JC
authors.lastname: Meitz
authors.forename: Anne P
authors.initials: AP
authors.lastname: Rehmany
authors.forename: Laura E
authors.initials: LE
authors.lastname: Rose
authors.forename: Jim L
authors.initials: JL
authors.lastname: Beynon
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D019470:Biolistics; D005075:Biological Evolution; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D005800:Genes, Fungal; D017343:Genes, Plant; D008969:Molecular Sequence Data; D009868:Oomycetes / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D010935:Plant Diseases / Q000382:microbiology; D011110:Polymorphism, Genetic; D021382:Protein Sorting Signals; D012641:Selection, Genetic
chemical_list: D029681:Arabidopsis Proteins; D005656:Fungal Proteins; D021382:Protein Sorting Signals; C408688:RPP13 protein, Arabidopsis