Host-pathogen interactions in natural populations of Linum marginale and Melampsora lini: II. Local and regional variation in patterns of resistance and racial structure

Abstract

Spatial variation in the resistance structure of wild flax populations to the rust fungus Melampsora lini, and in the racial structure of this pathogen, was investigated by sampling populations distributed throughout the Kosciusko National Park, New South Wales, Australia. The distribution of the four common races of M. lini was consistent with the hypothesis that a fitness cost was associated with unnecessary virulence. In general, however, differences in the structure of pathogen populations from genetically very similar host populations implied that, in addition to host resistance genes, other evolutionary forces are also important in determining the genetic structure of individual pathogen populations. -from Authors