Convergent evolution of disease resistance genes

The resistance genes Rpg1-b in soybean and RPM1 in Arabidopsis recognize the same bacterial avirulence protein (AvrB). Recent map-based cloning of Rpg1-b has provided the first opportunity to compare functionally analogous R genes in distantly related species. Rpg1-b and RPM1 are not orthologs. Rather, these genes descended from distinct evolutionary lineages in which recognition of AvrB has probably evolved independently. This result, together with new insights into RPM1-mediated recognition of AvrB, provides an exciting opportunity to reconsider classical views on the evolution of pathogen recognition specificity.