The genetic architecture of constitutive and induced trichome density in two new RIL populations of Arabidopsis thaliana: phenotypic plasticity, epistasis, and bidirectional leaf damage response

Background: Herbivory imposes an important selective pressure on plants. In Arabidopsis thaliana leaf trichomes provide a key defense against insect herbivory; however, trichome production incurs a fitness cost in the absence of herbivory. Previous work on A. thaliana has shown an increase in trichome density in response to leaf damage, suggesting a mechanism by which the cost associated with constitutively high trichome density might be mitigated; however, the genetic basis of trichome density induction has not been studied. Results: Here, we describe the mapping of quantitative trait loci (QTL) for constitutive and damage induced trichome density in two new recombinant inbred line populations of A. thaliana; mapping for constitutive and induced trichome density also allowed for the investigation of damage response (plasticity) QTL. Both novel and previously identified QTL for constitutive trichome density and the first QTL for induced trichome density and response are identified. Int...