Variation in Arabidopsis developmental responses to oomycete infection: Resilience vs changes in life history traits

Abstract

Summary: Although plant resistance to aggressors has been well described, there is still little knowledge about the mechanisms underlying their tolerance to pathogens. Tolerance often appears to be mediated by changes in life history traits, shifting host resource investment from growth to reproduction, but whether host phenotype modifications induced after attack are adaptive is not always clear. Here, we investigated the details of the impact of Hyaloperonospora arabidopsidis infection on several biomass, phenology and architectural traits of Arabidopsis thaliana, for three pathogen genotypes and three host plant genotypes that have been shown previously to differ greatly in fecundity and tolerance to infection. We found that, although host genotype explains most of the variance in life history traits, these three lines differ critically in their response to infection, with delays and biomass losses at bolting, together with changes in inflorescence architecture, observed at one extreme host line, and an advantage at bolting for infected plants and no inflorescence alteration for the other. These results suggest that the differences in tolerance observed previously in this pathosystem do not involve plasticity in inflorescence architecture, but may arise from induced changes at the vegetative stage, before plant transition to reproduction. © 2012 New Phytologist Trust.