Host resistance and pathogen virulence across a plant hybrid zone

• Published in: Oecologia Vol. 121; no. 3; pp. 339 - 347
• Main Authors: Carlsson-Graner, U, Burdon, J.J, Thrall, P.H
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01-11-1999; Springer
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; bags; Biological and medical sciences; biological resistance; Bog plants; Bogs; disease resistance; ecotypes; Fundamental and applied biological sciences. Psychology; hill land; Hybridity; Linum; Linum marginale; Melampsora; Melampsora lini; Pathogens; plant pathogenic fungi; Plants; Plants and fungi; Population ecology; Population mean; Population parameters; Population structure; Virulence; Hybrid zone; Hill; Melampsora lini; Plant pathogen; Biological evolution; Bogs; Basidiomycetes; Coevolution; Survival; Fungi; Gene flow; Sensitivity resistance; Linaceae; Dicotyledones; Angiospermae; Spermatophyta; Ecotype; Thallophyta; Linum; Melampsora; Key words Flax rust
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s004420050937

Hybridization between locally adapted plant populations has been postulated to have significant evolutionary consequences, and, in particular, may influence host-pathogen interactions with respect to resistance and virulence structure. This study investigated patterns of resistance and virulence in a hybrid zone between "bog" and "hill" ecotypes of the native Australian flax, Linum marginale, where the host is subject to attack by the rust pathogen, Melampsora lini. Analysis of the resistance structure of adjoining bog, hill and hybrid populations found that bog plants were generally susceptible to pathogen isolates taken from all these sites, but that hybrids exhibited resistance levels similar to the more resistant hill plants. Similarly, the virulence structure of rust isolates collected from the hybrid population was more similar to that of the hill isolates than the bog. Controlled crosses between bog and hill plants showed that crosses in one direction (bog females×hill males) were much more successful than the other. A multi-year reciprocal transplant study further indicated that bog plants had significantly higher survivorship than hill plants, regardless of site. It is suggested that likelihood of differential gene flow and survivorship for bog and hill plants may at least partially explain the maintenance of a relatively narrow hybrid zone.