title: Rapid incorporation of glucosinolates as a strategy used by a herbivore to prevent activation by myrosinases.
abstract: Various plants have a binary defence system that consists of a substrate and a glucosidase, which is activated upon tissue disruption thereby forming reactive hydrolysis products. Insects feeding on such plants have to overcome this binary defence system or prevent the activation. In this study, we investigated the strategy used by a herbivore to deal with such binary defence. We studied, how the larvae of the sawfly Athalia rosae (Hymenoptera: Tenthredinidae) circumvent the activation of glucosinolates by myrosinase enzymes, which are found in their Brassicaceae host plants. Myrosinase activities were low in the front part of the larval gut but activities increased over the gut passage. In contrast, the glucosinolates were only highly concentrated in the first gut part and were rapidly incorporated into the haemolymph before the food reached the second half of the gut. Thus, the uptake and concentration of glucosinolates, i.e., sequestration, must occur in the front part of the gut. Using Matrix Assisted Laser Desorption Ionization-Mass Spectrometry Imaging (MALDI-MSI), we could demonstrate that the incorporated glucosinolate sinalbin circulates in the haemolymph where it accumulates around the Malpighian tubules. This study highlights the pivotal role of the gut of an adapted herbivore as a regulatory functional organ to cope with plant toxins. MALDI-MSI turned out as a highly useful technique to visualise glucosinolates in a herbivore, which has to deal with plants exhibiting a binary defence system, and may be applied to follow the fate of plant metabolites in other insect species in the future.
authors.affiliation: Department of Chemical Ecology, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany.
authors.forename: Mohamed K
authors.initials: MK
authors.lastname: Abdalsamee
authors.affiliation: Center for Biotechnology and Department for Proteome and Metabolome Research, Bielefeld University, Universitätsstr. 27, 33615 Bielefeld, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Giampà
authors.affiliation: Center for Biotechnology and Department for Proteome and Metabolome Research, Bielefeld University, Universitätsstr. 27, 33615 Bielefeld, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Niehaus
authors.affiliation: Department of Chemical Ecology, Bielefeld University, Universitätsstr. 25, 33615 Bielefeld, Germany. Electronic address: caroline.mueller@uni-bielefeld.de.
authors.forename: Caroline
authors.initials: C
authors.lastname: Müller
mesh_terms: D000818:Animals; D002794:Choline / Q000031:analogs & derivatives / Q000378:metabolism; D004064:Digestive System / Q000737:chemistry* / Q000201:enzymology*; D005961:Glucosinolates / Q000378:metabolism / Q000494:pharmacology*; D006026:Glycoside Hydrolases / Q000378:metabolism; D006458:Hemolymph / Q000737:chemistry; D060434:Herbivory; D006927:Hymenoptera / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D007814:Larva / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000201:enzymology; D031226:Sinapis / Q000737:chemistry* / Q000201:enzymology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: D005961:Glucosinolates; D006026:Glycoside Hydrolases; C022739:thioglucosidase; D002794:Choline; C003313:sinalbin
keywords: Adaptation; Athalia rosae; Glucosinolate-myrosinase system; Imaging; Sequestration