title: Chemical defense balanced by sequestration and de novo biosynthesis in a lepidopteran specialist.
abstract: The evolution of sequestration (uptake and accumulation) relative to de novo biosynthesis of chemical defense compounds is poorly understood, as is the interplay between these two strategies. The Burnet moth Zygaena filipendulae (Lepidoptera) and its food-plant Lotus corniculatus (Fabaceae) poses an exemplary case study of these questions, as Z. filipendulae belongs to the only insect family known to both de novo biosynthesize and sequester the same defense compounds directly from its food-plant. Z. filipendulae and L. corniculatus both contain the two cyanogenic glucosides linamarin and lotaustralin, which are defense compounds that can be hydrolyzed to liberate toxic hydrogen cyanide. The overall amounts and ratios of linamarin and lotaustralin in Z. filipendulae are tightly regulated, and only to a low extent reflect the ratio in the ingested food-plant. We demonstrate that Z. filipendulae adjusts the de novo biosynthesis of CNglcs by regulation at both the transcriptional and protein level depending on food plant composition. Ultimately this ensures that the larva saves energy and nitrogen while maintaining an effective defense system to fend off predators. By using in situ PCR and immunolocalization, the biosynthetic pathway was resolved to the larval fat body and integument, which infers rapid replenishment of defense compounds following an encounter with a predator. Our study supports the hypothesis that de novo biosynthesis of CNglcs in Z. filipendulae preceded the ability to sequester, and facilitated a food-plant switch to cyanogenic plants, after which sequestration could evolve. Preservation of de novo biosynthesis allows fine-tuning of the amount and composition of CNglcs in Z. filipendulae.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Copenhagen, Denmark; VILLUM Research Center "Plant Plasticity", Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Joel
authors.initials: J
authors.lastname: Fürstenberg-Hägg
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Copenhagen, Denmark; VILLUM Research Center "Plant Plasticity", Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Mika
authors.initials: M
authors.lastname: Zagrobelny
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Copenhagen, Denmark; VILLUM Research Center "Plant Plasticity", Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Jørgensen
authors.affiliation: Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Vogel
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Copenhagen, Denmark; VILLUM Research Center "Plant Plasticity", Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Birger Lindberg
authors.initials: BL
authors.lastname: Møller
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, Copenhagen Plant Science Centre, University of Copenhagen, Copenhagen, Denmark; VILLUM Research Center "Plant Plasticity", Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Bak
mesh_terms: D000818:Animals; D007887:Fabaceae / Q000378:metabolism* / Q000502:physiology*; D005960:Glucosides / Q000378:metabolism; D006027:Glycosides / Q000378:metabolism; D007814:Larva / Q000378:metabolism / Q000502:physiology; D007915:Lepidoptera / Q000378:metabolism* / Q000502:physiology*; D000070116:Lotus / Q000378:metabolism / Q000502:physiology; D009036:Moths / Q000378:metabolism* / Q000502:physiology*; D009570:Nitriles / Q000378:metabolism
chemical_list: D005960:Glucosides; D006027:Glycosides; D009570:Nitriles; C005091:linamarin; C001556:lotaustralin