Constraints on the evolution of disease resistance in an annual legume

Abstract

An extensive survey of variation in disease resistance within one population of the annual legume Amphicarpaea bracteata revealed that only 11 per cent of the plants were resistant toward one native isolate of the pathogen Synchytrium decipiens. All plants completely lacked resistance toward two other native pathogen isolates. However, strong resistance to these pathogens was found among A. bracteata genotypes in nearby populations. These results imply that limits on the input of new resistance genes into local populations due to spatially-restricted gene flow may be a basic constraint on the evolution of disease resistance in this plant. © 1993 The Genetical Society of Great Britain.