Disclosed is substantially pure DNA encoding an Arabidopsis thaliana Rps2 polypeptide, substantially pure Rps2 polyneptide; and methods of using such DNA to express the Rps2 polypeptide in plant cells and whole plants to provide, in transgenic plants, disease resistance to pathogens. Also disclosed are conserved regions characteristic of the RPS family and primers and probes for the identification and isolation of additional RPS disease-resistance genes.