title: Dynamics of disease resistance polymorphism at the Rpm1 locus of Arabidopsis.
abstract: The co-evolutionary 'arms race' is a widely accepted model for the evolution of host-pathogen interactions. This model predicts that variation for disease resistance will be transient, and that host populations generally will be monomorphic at disease-resistance (R-gene) loci. However, plant populations show considerable polymorphism at R-gene loci involved in pathogen recognition. Here we have tested the arms-race model in Arabidopsis thaliana by analysing sequences flanking Rpm1, a gene conferring the ability to recognize Pseudomonas pathogens carrying AvrRpm1 or AvrB. We reject the arms-race hypothesis: resistance and susceptibility alleles at this locus have co-existed for millions of years. To account for the age of alleles and the relative levels of polymorphism within allelic classes, we use coalescence theory to model the long-term accumulation of nucleotide polymorphism in the context of the short-term ecological dynamics of disease resistance. This analysis supports a 'trench warfare' hypothesis, in which advances and retreats of resistance-allele frequency maintain variation for disease resistance as a dynamic polymorphism.
authors.affiliation: Committee on Genetics, University of Chicago, Illinois 60637, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Stahl
authors.forename: G
authors.initials: G
authors.lastname: Dwyer
authors.forename: R
authors.initials: R
authors.lastname: Mauricio
authors.forename: M
authors.initials: M
authors.lastname: Kreitman
authors.forename: J
authors.initials: J
authors.lastname: Bergelson
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000382:microbiology; D029681:Arabidopsis Proteins; D005787:Gene Frequency; D017343:Genes, Plant; D008954:Models, Biological; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics*; D011110:Polymorphism, Genetic; D011549:Pseudomonas / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; C095014:RPM1 protein, Arabidopsis