title: Expansion of a bitter taste receptor family in a polyphagous insect herbivore.
abstract: The Insect taste system plays a central role in feeding behaviours and co-evolution of insect-host interactions. Gustatory receptors form the interface between the insect taste system and the environment. From genome and transcriptome sequencing we identified 197 novel gustatory receptor (GR) genes from the polyphagous pest Helicoverpa armigera. These GRs include a significantly expanded bitter receptor family (180 GRs) that could be further divided into three categories based on polypeptide lengths, gene structure and amino acid sequence. Type 1 includes 29 bitter Gr genes that possess introns. Type 2 includes 13 long intronless bitter Gr genes, while Type 3 comprises 131 short intronless bitter Gr genes. Calcium imaging analysis demonstrated that three Type 3 GRs (HarmGR35, HarmGR50 and HarmGR195) can be activated by a crude extract of cotton leaves. HarmGR195, a GR specifically and selectively expressed in adult tarsi, showed a specific response to proline, an amino acid widely present in plant tissues. We hypothesise that the expansion in the H. armigera GR family may be functionally tied to its polyphagous behavior. Understanding the molecular basis of polyphagy may provide opportunities for the development of new environmentally friendly pest control strategies.
authors.affiliation: CSIRO Food and Nutrition Flagship, Black Mountain, ACT, Australia 2601.|School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, Australia 6150.
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.affiliation: CSIRO Land and Water Flagship, Black Mountain, ACT, Australia 2601.
authors.forename: Alexie
authors.initials: A
authors.lastname: Papanicolaou
authors.affiliation: CSIRO Food and Nutrition Flagship, Black Mountain, ACT, Australia 2601.
authors.forename: Hui-Jie
authors.initials: HJ
authors.lastname: Zhang
authors.affiliation: CSIRO Food and Nutrition Flagship, Black Mountain, ACT, Australia 2601.
authors.forename: Alisha
authors.initials: A
authors.lastname: Anderson
mesh_terms: D000596:Amino Acids; D000818:Animals; D012831:Bombyx / Q000235:genetics; D005091:Exons / Q000235:genetics; D005260:Female; D020869:Gene Expression Profiling; D017344:Genes, Insect; D016678:Genome; D060434:Herbivory; D019476:Insect Proteins / Q000235:genetics*; D007438:Introns / Q000235:genetics; D007814:Larva; D058446:Ligand-Gated Ion Channels / Q000235:genetics*; D008297:Male; D009036:Moths / Q000145:classification / Q000235:genetics* / Q000502:physiology; D010802:Phylogeny; D018515:Plant Leaves; D043562:Receptors, G-Protein-Coupled; D013045:Species Specificity; D059467:Transcriptome
chemical_list: D000596:Amino Acids; D019476:Insect Proteins; D058446:Ligand-Gated Ion Channels; D043562:Receptors, G-Protein-Coupled; C431926:taste receptors, type 1