title: Trade-off between constitutive and inducible resistance against herbivores is only partially explained by gene expression and glucosinolate production.
abstract: The hypothesis that constitutive and inducible plant resistance against herbivores should trade-off because they use the same resources and impose costs to plant fitness has been postulated for a long time. Negative correlations between modes of deployment of resistance and defences have been observed across and within species in common garden experiments. It was therefore tested whether that pattern of resistance across genotypes follows a similar variation in patterns of gene expression and chemical defence production. Using the genetically tractable model Arabidopsis thaliana and different modes of induction, including the generalist herbivore Spodoptera littoralis, the specialist herbivore Pieris brassicae, and jasmonate application, constitutive and inducibility of resistance was measured across seven A. thaliana accessions that were previously selected based on constitutive levels of defence gene expression. According to theory, it was found that modes of resistance traded-off among accessions, particularly against S. littoralis, in which accessions investing in high constitutive resistance did not increase it substantially after attack and vice-versa. Accordingly, the average expression of eight genes involved in glucosinolate production negatively predicted larval growth across the seven accessions. Glucosinolate production and genes related to defence induction on healthy and herbivore-damaged plants were measured next. Surprisingly, only a partial correlation between glucosinolate production, gene expression, and the herbivore resistance results was found. These results suggest that the defence outcome of plants against herbivores goes beyond individual molecules or genes but stands on a complex network of interactions.
authors.affiliation: Institute of Biology, University of Neuchâtel, 2000 Neuchatel, Switzerland sergio.rasmann@unine.ch.
authors.forename: Sergio
authors.initials: S
authors.lastname: Rasmann
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Biophore building, 1015 Lausanne, Switzerland.
authors.forename: Estelle
authors.initials: E
authors.lastname: Chassin
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Biophore building, 1015 Lausanne, Switzerland.
authors.forename: Julia
authors.initials: J
authors.lastname: Bilat
authors.affiliation: Neuchâtel Platform of Analytical Chemistry, University of Neuchatel, 2000 Neuchatel, Switzerland.
authors.forename: Gaétan
authors.initials: G
authors.lastname: Glauser
authors.affiliation: Department of Plant Molecular Biology, University of Lausanne, Biophore building, 1015 Lausanne, Switzerland.
authors.forename: Philippe
authors.initials: P
authors.lastname: Reymond
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D003517:Cyclopentanes / Q000494:pharmacology; D005247:Feeding Behavior; D018506:Gene Expression Regulation, Plant; D005961:Glucosinolates / Q000378:metabolism*; D060434:Herbivory; D054883:Oxylipins / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018411:Spodoptera / Q000502:physiology
chemical_list: D003517:Cyclopentanes; D005961:Glucosinolates; D054883:Oxylipins; D010937:Plant Growth Regulators; C011006:jasmonic acid
keywords: Glucosinolates; VSP2; jasmonic acid; plant defences; plant–herbivore interaction; specificity of resistance