title: Differential gene expression according to race and host plant in the pea aphid.
abstract: Host-race formation in phytophagous insects is thought to provide the opportunity for local adaptation and subsequent ecological speciation. Studying gene expression differences amongst host races may help to identify phenotypes under (or resulting from) divergent selection and their genetic, molecular and physiological bases. The pea aphid (Acyrthosiphon pisum) comprises host races specializing on numerous plants in the Fabaceae and provides a unique system for examining the early stages of diversification along a gradient of genetic and associated adaptive divergence. In this study, we examine transcriptome-wide gene expression both in response to environment and across pea aphid races selected to cover the range of genetic divergence reported in this species complex. We identify changes in expression in response to host plant, indicating the importance of gene expression in aphid-plant interactions. Races can be distinguished on the basis of gene expression, and higher numbers of differentially expressed genes are apparent between more divergent races; these expression differences between host races may result from genetic drift and reproductive isolation and possibly divergent selection. Expression differences related to plant adaptation include a subset of chemosensory and salivary genes. Genes showing expression changes in response to host plant do not make up a large portion of between-race expression differences, providing confirmation of previous studies' findings that genes involved in expression differences between diverging populations or species are not necessarily those showing initial plasticity in the face of environmental change.
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN, UK.
authors.forename: Isobel
authors.initials: I
authors.lastname: Eyres
authors.affiliation: CNRS UMR 6553 ECOBIO, Université de Rennes 1, Avenue du Général Leclerc, Campus de Beaulieu, 35042, Rennes Cedex, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Jaquiéry
authors.affiliation: INRA, Institut de Génétique, Environnement et Protection des Plantes, UMR 1349 IGEPP, Domaine de la Motte, 35653, Le Rheu Cedex, France.
authors.forename: Akiko
authors.initials: A
authors.lastname: Sugio
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN, UK.
authors.forename: Ludovic
authors.identifier: 0000-0003-0960-0312
authors.initials: L
authors.lastname: Duvaux
authors.affiliation: Edinburgh Genomics, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK.
authors.forename: Karim
authors.initials: K
authors.lastname: Gharbi
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, AL5 2JQ, UK.
authors.forename: Jing-Jiang
authors.initials: JJ
authors.lastname: Zhou
authors.affiliation: INRA, Institut de Génétique, Environnement et Protection des Plantes, UMR 1349 IGEPP, Domaine de la Motte, 35653, Le Rheu Cedex, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Legeai
authors.affiliation: Department of Biology, University of York, York, UK.
authors.forename: Michaela
authors.initials: M
authors.lastname: Nelson
authors.affiliation: INRA, Institut de Génétique, Environnement et Protection des Plantes, UMR 1349 IGEPP, Domaine de la Motte, 35653, Le Rheu Cedex, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Simon
authors.affiliation: Institut des Sciences de l'Evolution (UMR 5554 CNRS-IRD-CIRAD-Université de Montpellier), Université Montpellier 2, cc065, Place Bataillon, 34095, Montpellier Cedex 05, France.
authors.forename: Carole M
authors.initials: CM
authors.lastname: Smadja
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield, S10 2TN, UK.
authors.forename: Roger
authors.initials: R
authors.lastname: Butlin
authors.affiliation: Department of Biology, University of York, York, UK.
authors.forename: Julia
authors.initials: J
authors.lastname: Ferrari
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D001042:Aphids / Q000235:genetics*; D004777:Environment; D007887:Fabaceae; D040961:Genetic Drift; D005828:Genetics, Population; D010641:Phenotype; D060047:Reproductive Isolation; D012641:Selection, Genetic; D059467:Transcriptome
keywords: gene expression; host adaptation; pea aphid; plant-insect interactions; speciation; transcriptome