title: The effect of environmental heterogeneity on RPW8-mediated resistance to powdery mildews in Arabidopsis thaliana.
abstract: OBJECTIVE
  The biotic and abiotic environment of interacting hosts and parasites may vary considerably over small spatial and temporal scales. It is essential to understand how different environments affect host disease resistance because this determines frequency of disease and, importantly, heterogeneous environments can retard direct selection and potentially maintain genetic variation for resistance in natural populations.
  
  
  METHODS
  The effect of different temperatures and soil nutrient conditions on the outcome of infection by a pathogen was quantified in Arabidopsis thaliana. Expression levels of a gene conferring resistance to powdery mildews, RPW8, were compared with levels of disease to test a possible mechanism behind variation in resistance.
  
  
  RESULTS
  Most host genotypes changed from susceptible to resistant across environments with the ranking of genotypes differing between treatments. Transcription levels of RPW8 increased after infection and varied between environments, but there was no tight association between transcription and resistance levels.
  
  
  CONCLUSIONS
  There is a strong potential for a heterogeneous environment to change the resistance capacity of A. thaliana genotypes and hence the direction and magnitude of selection in the presence of the pathogen. Possible causative links between resistance gene expression and disease resistance are discussed in light of the present results on RPW8.
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich Research Park, UK. t.jorgensen@uea.ac.uk
authors.forename: Tove H
authors.initials: TH
authors.lastname: Jorgensen
mesh_terms: D017360:Arabidopsis / Q000382:microbiology* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000235:genetics; D001203:Ascomycota / Q000472:pathogenicity*; D060467:Disease Resistance; D018506:Gene Expression Regulation, Plant; D059647:Gene-Environment Interaction; D017343:Genes, Plant; D014644:Genetic Variation; D010935:Plant Diseases / Q000382:microbiology*; D012987:Soil / Q000737:chemistry; D013696:Temperature; D014158:Transcription, Genetic; D006113:United Kingdom
chemical_list: D029681:Arabidopsis Proteins; D012987:Soil