@article{d37a1db2a54749488b8b86cd5f9c00fd,
title = "Genome sequence of the wheat stem sawfly, cephus cinctus, representing an early-branching lineage of the hymenoptera, illuminates evolution of hymenopteran chemoreceptors",
abstract = "The wheat stem sawfly, Cephus cinctus, is a major pest of wheat and key ecological player in the grasslands of western North America. It also represents the distinctive Cephoidea superfamily of sawflies (Symphyta) that appeared early during the hymenopteran radiation, but after three early-branching eusymphytan superfamilies that form the base of the order Hymenoptera. We present a high-quality draft genome assembly of 162 Mb in 1,976 scaffolds with a scaffold N50 of 622 kb. Automated gene annotation identified 11,210 protein-coding gene models and 1,307 noncoding RNA models. Thirteen percent of the assembly consists of 58,000 transposable elements partitioned equally between Class-I and Class-II elements. Orthology analysis reveals that 86% of Cephus proteins have identifiable orthologs in other insects. Phylogenomic analysis of conserved subsets of these proteins supports the placement of the Cephoidea between the Eusymphyta and the parasitic woodwasp superfamily Orussoidea. Manual annotation and phylogenetic analysis of families of odorant, gustatory, and ionotropic receptors, plus odorant-binding proteins, shows that Cephus has representatives for most conserved and expanded gene lineages in the Apocrita (wasps, ants, and bees). Cephus has also maintained several insect gene lineages that have been lost from the Apocrita, most prominently the carbon dioxide receptor subfamily. Furthermore, Cephus encodes a few small lineage-specific chemoreceptor gene family expansions that might be involved in adaptations to new grasses including wheat. These comparative analyses identify gene family members likely to have been present in the hymenopteran ancestor and provide a new perspective on the evolution of the chemosensory gene repertoire.",
keywords = "Cephidae, Cephoidea, Gustatory receptor, Ionotropic receptor, Odorant receptor, Odorant-binding protein",
author = "Robertson, {Hugh M.} and Waterhouse, {Robert M.} and Walden, {Kimberly K.O.} and Livio Ruzzante and Reijnders, {Maarten J.M.F.} and Coates, {Brad S.} and Fabrice Legeai and Gress, {Joanna C.} and Sezgi Biyiklioglu and Weaver, {David K.} and Wanner, {Kevin W.} and Hikmet Budak",
note = "We thank Alvaro Hernandez and the W.M. Keck Center for Comparative and Functional Genomics at the University of Illinois at Urbana-Champaign for genomic and RNA library construction and sequencing; Daniel Ence and Mark Yandell (University of Utah) for annotation of an earlier version of the genome assembly; Terence Murphy for assistance with the NCBI annotation; Monica Poelchau and Chris Childers for assistance with the i5k Workspace@NAL browser and official gene set v1.1; Chris Elsik for an Apollo browser at NasoniaBase; Masatsugu Hatakeyama, Bernhard Misof, Oliver Niehuis, and Jan Philip Oeyen for granting prepublication access to gene annotations of Athalia rosae and Orussus abietinus; and Megan Hofland and Norma Irish for preparing figure 1. This work was supported by funding from the United States Department of Agriculture (Grant Number AG2008-35302-188815 to H.M.R. and K.W.W.), Swiss National Science Foundation (Grant Number PP00P3_170664 to R.M.W.), the Winifred-Asbjornson Plant Science Endowment to H.B., the Montana Wheat and Barley Committee and the Montana Grains Foundation to D.K.W. and K.W.W., who also received funds supporting this research from the AES allocation in HB 645 of the 61st Legislature of the State of Montana, and a contribution from Gene Robinson (University of Illinois at Urbana-Champaign). Part of this research was the result of a joint contribution from the United States Department of Agriculture (USDA), Agricultural Research Service (ARS) (CRIS Project 5030-22000-018-00D), and the Iowa Agriculture and Home Economics Experiment Station, Ames, IA (Project 3543). USDA is an equal employment opportunity provider. This article reports the results of research only.",
year = "2018",
doi = "10.1093/gbe/evy232",
language = "English (US)",
volume = "10",
pages = "2997--3011",
journal = "Genome biology and evolution",
issn = "1759-6653",
publisher = "Oxford University Press",
number = "11",
}