Thursday, August 5, 2010: 10:50 AM
411, David L Lawrence Convention Center
Background/Question/Methods
Pathogens exert selection for resistance on host plant populations, which results in corresponding selection for virulence in pathogen populations. Host plant hybridization can disrupt such tightly coevolved host-pathogen interactions by creating a genetic continuum between parental host species. However, few studies have explored how pathogens respond to the genetic diversity of closely related species and their naturally occurring hybrids. Here, we report on the abundance and distribution of fungal leaf pathogens infecting Populus fremontii, P. angustifolia and their naturally occurring hybrids in stands along the Weber river in northern Utah, and in common gardens containing replicate clones of individual tree genotypes.
Pathogens exert selection for resistance on host plant populations, which results in corresponding selection for virulence in pathogen populations. Host plant hybridization can disrupt such tightly coevolved host-pathogen interactions by creating a genetic continuum between parental host species. However, few studies have explored how pathogens respond to the genetic diversity of closely related species and their naturally occurring hybrids. Here, we report on the abundance and distribution of fungal leaf pathogens infecting Populus fremontii, P. angustifolia and their naturally occurring hybrids in stands along the Weber river in northern Utah, and in common gardens containing replicate clones of individual tree genotypes.
Results/Conclusions
We found that: 1) different tree genotypes support different fungal pathogen communities, 2) there is significant broad-sense heritability of plant resistance to the fungal pathogen community, and 3) fungal pathogens have shifted from native to non-native hosts. Our results suggest that plant hybridization enables host shifting by providing pathogens with a genetic continuum for adaptation. To our knowledge, our results are the first to demonstrate the broad-sense heritability of plant resistance to natural pathogen communities. Furthermore, these findings suggest both inter- and intraspecific genetic variation in foundational hosts determine the evolutionary trajectory of pathogen communities.
