Fitness costs of R-gene-mediated resistance in Arabidopsis thaliana

• Published in: Nature (London) Vol. 423; no. 6935; pp. 74 - 77
• Main Authors: Bergelson, J, Tian, D, Traw, M. B, Chen, J. Q, Kreitman, M
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 01.05.2003; Nature Publishing Group
• Subjects: Alleles; Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biological and medical sciences; Flowers & plants; Fundamental and applied biological sciences. Psychology; Generalities. Disease free stocks; Genes; Genes, Plant - genetics; Haplotypes - genetics; Immune system; Immunity, Innate - genetics; Models, Biological; Pathogens; Phenotype; Phytopathology. Animal pests. Plant and forest protection; Polymerase Chain Reaction; Polymorphism, Genetic - genetics; Promoter Regions, Genetic - genetics; Seeds - genetics; Seeds - physiology; Selection, Genetic; Arabidopsis thaliana; Microorganism resistance; Gene; Cruciferae; Dicotyledones; Angiospermae; Spermatophyta; Experimental plant; Cost benefit analysis; Gene expression; Fitness
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature01588

Resistance genes (R-genes) act as an immune system in plants by recognizing pathogens and inducing defensive pathways. Many R-gene loci are present in plant genomes, presumably reflecting the need to maintain a large repertoire of resistance alleles. These loci also often segregate for resistance and susceptibility alleles that natural selection has maintained as polymorphisms within a species for millions of years. Given the obvious advantage to an individual of being disease resistant, what prevents these resistance alleles from being driven to fixation by natural selection? A cost of resistance is one potential explanation; most models require a lower fitness of resistant individuals in the absence of pathogens for long-term persistence of susceptibility alleles. Here we test for the presence of a cost of resistance at the RPM1 locus of Arabidopsis thaliana. Results of a field experiment comparing the fitness of isogenic strains that differ in the presence or absence of RPM1 and its natural promoter reveal a large cost of RPM1, providing the first evidence that costs contribute to the maintenance of an ancient R-gene polymorphism.