Evolutionary implications of plant host interactions with a generalist pathogen.
Hanna Märkle1,2, Theo L Gibbs1, Joy Bergelson1,2
1Department of Biology, New York University Center for Genomics and Systems Biology, New York, NY, USA.
Proceedings. Biological Sciences
|March 17, 2026
Summary
Shared generalist pathogens can maintain diverse resistance (R) gene polymorphisms across related host species. Alternative host proportions influence R gene evolution, potentially leading to trans-specific R gene polymorphism.
Area of Science:
- Evolutionary biology
- Plant pathology
- Population genetics
Background:
- Host-pathogen interactions drive the evolution of resistance (R) genes and their polymorphisms.
- Some R genes display strong balancing selection and trans-specific polymorphism.
- Understanding the influence of alternative hosts on R gene evolution is crucial.
Purpose of the Study:
- To model how shared host-pathogen interactions shape R gene repertoires and polymorphism in two related host species.
- To identify conditions favoring the maintenance of trans-specific R gene polymorphism.
- To investigate the impact of host population proportions on R gene evolution.
Main Methods:
- Developed a simple mathematical model of host-pathogen interactions.
- Simulated interactions between two closely related host species and a single generalist pathogen.
- Analyzed R gene dynamics, polymorphism maintenance, and fixation patterns under varying host proportions.
Main Results:
- Interactions with a generalist pathogen more effectively sustain polymorphism at shared R genes than at private R genes.
- Shared R genes can lead to trans-specific resistance gene polymorphism.
- Increased prevalence of one host species favors private resistance fixation in the less common host, as the pathogen adapts.
Conclusions:
- Shared generalist pathogens play a key role in maintaining trans-specific R gene polymorphism.
- Host population dynamics significantly influence the evolution of private resistance genes.
- The model provides insights into R gene evolution shaped by pathogen adaptation to alternative hosts.
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