Genetic independence of naturally correlated variation in resistance to endemic and novel pathogens

With anther-smut disease from wild populations, we used selection experiments and genetic analyses to show that, although positively correlated, novel and endemic-pathogen resistances are genetically independent, with contrasting modes of inheritance.  We demonstrate that polymorphic resistance to a newly introduced disease is genetically determined and not an extension of defenses against the related endemic pathogen, challenging the conventional view of nonhost resistance.

Methods
Data were collected from greenhouse-grown plants of Silene vulgaris, assessing their infection status after inoculation with the fungal pathogen, Microbotryum sp.  Data are presented as counts of healthy or diseased plants, without other processing.