Gene expansion in the hawkmoth Manduca sexta drives evolution of food-associated odorant receptors
Megha Treesa Tom,
Philipp Brand,
Sascha Bucks,
Jin Zhang,
Mario Ernesto Escobar Huezo,
Bill S. Hansson,
Sonja Bisch-Knaden
Affiliations
Megha Treesa Tom
Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
Philipp Brand
Laboratory of Neurophysiology and Behavior, The Rockefeller University, New York, NY, USA
Sascha Bucks
Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
Jin Zhang
Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany; Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
Mario Ernesto Escobar Huezo
Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
Bill S. Hansson
Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany
Sonja Bisch-Knaden
Department of Evolutionary Neuroethology, Max-Planck Institute for Chemical Ecology, Jena, Germany; Corresponding author
Summary: In insects, odorant receptors (ORs) are required for the detection of most olfactory cues. We investigated the function of a clade of four duplicated ORs in the hawkmoth Manduca sexta and found that these paralogs encode broadly tuned receptors with overlapping but distinct response spectra. Two paralogs, which arose after divergence from a related lineage, show high sensitivity to floral esters released by a nectar-rich plant frequently visited by M. sexta. Functional imaging in mutant moths lacking one of the paralogs suggests that olfactory sensory neurons expressing this OR target a previously identified feeding-associated glomerulus in the primary olfactory center of the brain. However, only the response of this glomerulus to the single ligand unique to the now mutated OR disappeared, suggesting neuronal coexpression of the paralogs. Our results suggest a link between the studied OR expansion and enhanced detection of odors emitted by valuable nectar sources in M. sexta.
