Abstract
BackgroundHerbivory 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.ResultsHere, 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. Interestingly, two of the four parental accessions and multiple RILs in each population exhibited lower trichome density following leaf damage, a response not previously described in A. thaliana. Importantly, a single QTL was mapped for the response phenotype and allelic variation at this locus appears to determine response trajectory in RILs. The data also show that epistatic interactions are a significant component of the genetic architecture of trichome density.ConclusionsTogether, our results provide further insights into the genetic architecture of constitutive trichome density and new insights into induced trichome density in A. thaliana specifically and to our understanding of the genetic underpinnings of natural variation generally.
Highlights
Herbivory imposes an important selective pressure on plants
Residual heterozygosity across all markers was 1.12% in the Hi-0 x Ob-0 (HO) population and 1.36% in the St-0 × Sf-2 (SS) population (Table 1). This is low and similar to that reported for other Recombinant Inbred Line (RIL) populations [15,32,33] but slightly higher than the
HO RILs exhibited segregation distortion localized to regions of chromosomes I, IV and V with preferred parental alleles varying by genomic region
Summary
Herbivory imposes an important selective pressure on plants. In Arabidopsis thaliana leaf trichomes provide a key defense against insect herbivory; trichome production incurs a fitness cost in the absence of herbivory. A fitness cost for trichomes has been shown in the wild relatives A. kamchatica [6] and A. halleri ssp gemmifera [7], with evidence of divergent selection for trichome density identified in A. kamchatica and A. lyrata [8] Reflecting these conflicting selection pressures, constitutive trichome density is highly variable among natural accessions of A. thaliana with a strong genetic basis to the observed variation under controlled conditions [9,10,11]. Induction of trichome initiation has not been demonstrated in the field in A. thaliana [3], trichome production is induced by artificial wounding of early leaves [12] Such phenotypic plasticity implies a mechanism by which A. thaliana may offset some of the cost of producing trichomes, investing in higher density only when required. The genetic basis of induced trichome density and plasticity of trichome density have not been studied, these are perhaps more meaningful traits in nature, as they capture the ability of plants to respond to the dynamic selective forces at play
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call