title: Tissue-specific transcript profiling for ABC transporters in the sequestering larvae of the phytophagous leaf beetle Chrysomela populi.
abstract: BACKGROUND
  Insects evolved ingenious adaptations to use extraordinary food sources. Particularly, the diet of herbivores enriched with noxious plant secondary metabolites requires detoxification mechanisms. Sequestration, which involves the uptake, transfer, and concentration of occasionally modified phytochemicals into specialized tissues or hemolymph, is one of the most successful detoxification strategies found in most insect orders. Due to the ability of ATP-binding cassette (ABC) carriers to transport a wide range of molecules including phytochemicals and xenobiotics, it is highly likely that they play a role in this sequestration process. To shed light on the role of ABC proteins in sequestration, we describe an inventory of putative ABC transporters in various tissues in the sequestering juvenile poplar leaf beetle, Chrysomela populi.
  
  
  RESULTS
  In the transcriptome of C. populi, we predicted 65 ABC transporters. To link the proteins with a possible function, we performed comparative phylogenetic analyses with ABC transporters of other insects and of humans. While tissue-specific profiling of each ABC transporter subfamily suggests that ABCB, C and G influence the plant metabolite absorption in the gut, ABCC with 14 members is the preferred subfamily responsible for the excretion of these metabolites via Malpighian tubules. Moreover, salicin, which is sequestered from poplar plants, is translocated into the defensive glands for further deterrent production. In these glands and among all identified ABC transporters, an exceptionally high transcript level was observed only for Cpabc35 (Cpmrp). RNAi revealed the deficiency of other ABC pumps to compensate the function of CpABC35, demonstrating its key role during sequestration.
  
  
  CONCLUSIONS
  We provide the first comprehensive phylogenetic study of the ABC family in a phytophagous beetle species. RNA-seq data from different larval tissues propose the importance of ABC pumps to achieve a homeostasis of plant-derived compounds and offer a basis for future analyses of their physiological function in sequestration processes.
authors.affiliation: Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knoell-Str. 8, D-07745 Jena, Thuringia, Germany.
authors.forename: Anja S
authors.initials: AS
authors.lastname: Strauss
authors.affiliation: Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knoell-Str. 8, D-07745 Jena, Thuringia, Germany.
authors.forename: Ding
authors.initials: D
authors.lastname: Wang
authors.affiliation: Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knoell-Str. 8, D-07745 Jena, Thuringia, Germany.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Stock
authors.affiliation: Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knoell-Str. 8, D-07745 Jena, Thuringia, Germany.
authors.forename: René R
authors.initials: RR
authors.lastname: Gretscher
authors.affiliation: Leibniz Institute for Age Research - Fritz Lipmann Institute, Beutenbergstr. 11, D-07745 Jena, Thuringia, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Groth
authors.affiliation: Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knoell-Str. 8, D-07745 Jena, Thuringia, Germany.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Boland
authors.affiliation: Max Planck Institute for Chemical Ecology, Beutenberg Campus, Hans-Knoell-Str. 8, D-07745 Jena, Thuringia, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Burse
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000818:Animals; D001517:Coleoptera / Q000235:genetics* / Q000254:growth & development; D020869:Gene Expression Profiling; D007814:Larva / Q000235:genetics*; D010802:Phylogeny; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D018528:ATP-Binding Cassette Transporters; D012333:RNA, Messenger