title: Glucosinolate Desulfation by the Phloem-Feeding Insect Bemisia tabaci.
abstract: Glucosinolates are plant secondary defense metabolites confined nearly exclusively to the order Brassicales. Upon tissue rupture, glucosinolates are hydrolyzed to various bioactive breakdown products by the endogenous plant enzyme myrosinase. As the feeding of chewing insect herbivores is associated with plant tissue damage, these insects have developed several independent strategies for coping with the glucosinolate-myrosinase defense system. On the other hand, our knowledge of how phloem-feeding insects interact with the glucosinolate-myrosinase system is much more limited. In fact, phloem feeders might avoid contact with myrosinase altogether so their susceptibility to intoxication by glucosinolate hydrolysis products is unclear. Previous studies utilizing Arabidopsis thaliana plants accumulating high levels of aliphatic- or indolic-glucosinolates indicated that both glucosinolate groups have moderate negative effects on the reproductive performance of Bemisia tabaci, a generalist phloem-feeding insect. To get a deeper understanding of the interaction between B. tabaci and glucosinolate-defended plants, adults were allowed to feed on artificial diet containing intact glucosinolates or on Brussels sprout and A. thaliana plants, and their honeydew was analyzed for the presence of possible metabolites. We found that B. tabaci is capable of cleaving off the sulfate group of intact glucosinolates, producing desulfoglucosinolates that cannot be activated by myrosinases, a mechanism described to date only in several chewing insect herbivores. The presence of desulfated glucosinolates in the honeydew of a generalist phloem-feeder may indicate the necessity to detoxify glucosinolates, likely due to some level of cellular damage during feeding, which results in glucosinolate activation, or as a mechanism to circumvent the non-enzymatic breakdown of indolic glucosinolates.
authors.affiliation: Department of Entomology, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel. osnat226@gmail.com.
authors.forename: Osnat
authors.initials: O
authors.lastname: Malka
authors.affiliation: Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745, Jena, Germany.
authors.forename: Anton
authors.initials: A
authors.lastname: Shekhov
authors.affiliation: Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745, Jena, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Reichelt
authors.affiliation: Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745, Jena, Germany.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gershenzon
authors.affiliation: Max Planck Institute for Chemical Ecology, Hans-Knoell-Str. 8, 07745, Jena, Germany.
authors.forename: Daniel Giddings
authors.initials: DG
authors.lastname: Vassão
authors.affiliation: Department of Entomology, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel.
authors.forename: Shai
authors.initials: S
authors.lastname: Morin
mesh_terms: D000818:Animals; D002853:Chromatography, Liquid; D005247:Feeding Behavior; D005961:Glucosinolates / Q000378:metabolism*; D006430:Hemiptera / Q000502:physiology*; D013058:Mass Spectrometry; D013431:Sulfates / Q000378:metabolism*
chemical_list: D005961:Glucosinolates; D013431:Sulfates
keywords: Aliphatic-glucosinolates; Bemisia tabaci; Detoxification; Indolic-glucosinolates; Phloem-feeders; Plant secondary metabolite; Sulfatase