title: Putative sugar transporters of the mustard leaf beetle Phaedon cochleariae: their phylogeny and role for nutrient supply in larval defensive glands.
abstract: BACKGROUND
  Phytophagous insects have emerged successfully on the planet also because of the development of diverse and often astonishing defensive strategies against their enemies. The larvae of the mustard leaf beetle Phaedon cochleariae, for example, secrete deterrents from specialized defensive glands on their back. The secretion process involves ATP-binding cassette transporters. Therefore, sugar as one of the major energy sources to fuel the ATP synthesis for the cellular metabolism and transport processes, has to be present in the defensive glands. However, the role of sugar transporters for the production of defensive secretions was not addressed until now.
  
  
  RESULTS
  To identify sugar transporters in P. cochleariae, a transcript catalogue was created by Illumina sequencing of cDNA libraries. A total of 68,667 transcripts were identified and 68 proteins were annotated as either members of the solute carrier 2 (SLC2) family or trehalose transporters. Phylogenetic analyses revealed an extension of the mammalian GLUT6/8 class in insects as well as one group of transporters exhibiting distinctive conserved motifs only present in the insect order Coleoptera. RNA-seq data of samples derived from the defensive glands revealed six transcripts encoding sugar transporters with more than 3,000 counts. Two of them are exclusively expressed in the glandular tissue. Reduction in secretions production was accomplished by silencing two of four selected transporters. RNA-seq experiments of transporter-silenced larvae showed the down-regulation of the silenced transporter but concurrently the up-regulation of other SLC2 transporters suggesting an adaptive system to maintain sugar homeostasis in the defensive glands.
  
  
  CONCLUSIONS
  We provide the first comprehensive phylogenetic study of the SLC2 family in a phytophagous beetle species. RNAi and RNA-seq experiments underline the importance of SLC2 transporters in defensive glands to achieve a chemical defense for successful competitive interaction in natural ecosystems.
authors.affiliation: Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Thuringia, Germany.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Stock
authors.affiliation: Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Thuringia, Germany.
authors.forename: René R
authors.initials: RR
authors.lastname: Gretscher
authors.affiliation: Genome Analysis Group, Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Thuringia, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Groth
authors.affiliation: Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Thuringia, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Eiserloh
authors.affiliation: Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Thuringia, Germany.
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Boland
authors.affiliation: Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Thuringia, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Burse
mesh_terms: D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D001517:Coleoptera / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D005088:Exocrine Glands / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D020869:Gene Expression Profiling; D015723:Gene Library; D007814:Larva / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D018076:DNA, Complementary; D009004:Monosaccharide Transport Proteins