title: Phyllotreta striolata flea beetles use host plant defense compounds to create their own glucosinolate-myrosinase system.
abstract: The ability of a specialized herbivore to overcome the chemical defense of a particular plant taxon not only makes it accessible as a food source but may also provide metabolites to be exploited for communication or chemical defense. Phyllotreta flea beetles are adapted to crucifer plants (Brassicales) that are defended by the glucosinolate-myrosinase system, the so-called "mustard-oil bomb." Tissue damage caused by insect feeding brings glucosinolates into contact with the plant enzyme myrosinase, which hydrolyzes them to form toxic compounds, such as isothiocyanates. However, we previously observed that Phyllotreta striolata beetles themselves produce volatile glucosinolate hydrolysis products. Here, we show that P. striolata adults selectively accumulate glucosinolates from their food plants to up to 1.75% of their body weight and express their own myrosinase. By combining proteomics and transcriptomics, a gene responsible for myrosinase activity in P. striolata was identified. The major substrates of the heterologously expressed myrosinase were aliphatic glucosinolates, which were hydrolyzed with at least fourfold higher efficiency than aromatic and indolic glucosinolates, and β-O-glucosides. The identified beetle myrosinase belongs to the glycoside hydrolase family 1 and has up to 76% sequence similarity to other β-glucosidases. Phylogenetic analyses suggest species-specific diversification of this gene family in insects and an independent evolution of the beetle myrosinase from other insect β-glucosidases.
authors.affiliation: Departments of Entomology, fberan@ice.mpg.de.
authors.forename: Franziska
authors.initials: F
authors.lastname: Beran
authors.affiliation: Departments of Entomology.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Pauchet
authors.affiliation: Biochemistry.
authors.forename: Grit
authors.initials: G
authors.lastname: Kunert
authors.affiliation: Biochemistry.
authors.forename: Michael
authors.initials: M
authors.lastname: Reichelt
authors.affiliation: Mass Spectrometry.
authors.forename: Natalie
authors.initials: N
authors.lastname: Wielsch
authors.affiliation: Departments of Entomology.
authors.forename: Heiko
authors.initials: H
authors.lastname: Vogel
authors.affiliation: Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany;
authors.forename: Andreas
authors.initials: A
authors.lastname: Reinecke
authors.affiliation: Mass Spectrometry.
authors.forename: Aleš
authors.initials: A
authors.lastname: Svatoš
authors.affiliation: Quality, Leibniz Institute of Vegetable and Ornamental Crops Grossbeeren/Erfurt e.V., 14979 Grossbeeren, Germany; and.
authors.forename: Inga
authors.initials: I
authors.lastname: Mewis
authors.affiliation: Bioorganic Chemistry, and.
authors.forename: Daniela
authors.initials: D
authors.lastname: Schmid
authors.affiliation: Entomology, AVRDC-The World Vegetable Center, Tainan 74151, Taiwan.
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Ramasamy
authors.affiliation: Urban Plant Ecophysiology, Humboldt-Universität zu Berlin, 14195 Berlin, Germany;
authors.forename: Christian
authors.initials: C
authors.lastname: Ulrichs
authors.affiliation: Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, 07745 Jena, Germany;
authors.forename: Bill S
authors.initials: BS
authors.lastname: Hansson
authors.affiliation: Biochemistry.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gershenzon
authors.affiliation: Departments of Entomology.
authors.forename: David G
authors.initials: DG
authors.lastname: Heckel
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000737:chemistry*; D044602:Cellulases / Q000378:metabolism; D001517:Coleoptera / Q000201:enzymology / Q000276:immunology* / Q000502:physiology; D020224:Expressed Sequence Tags; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D005961:Glucosinolates / Q000737:chemistry*; D006026:Glycoside Hydrolases / Q000378:metabolism*; D060434:Herbivory; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D005961:Glucosinolates; D010940:Plant Proteins; D044602:Cellulases; D006026:Glycoside Hydrolases; C022739:thioglucosidase
keywords: convergent evolution; host plant specialization