Expressed sequence tags from cephalic chemosensory organs of the northern walnut husk fly, Rhagoletis suavis, including a putative canonical odorant receptor

Karlene M. M. Ramsdell1a, Sheila A. Lyons-Sobaski2b, Hugh M. Robertson1c, Kimberly K. O. Walden1d, Jeffrey L. Feder3e, Kevin Wanner1f, and Stewart H. Berlocher1g

1Department of Entomology, 320 Morrill Hall, 505 S. Goodwin Ave., University of Illinois at Urbana-Champaign, Urbana, IL 61801
2Department of Biology, Albion College, 611 E. Porter St., Albion, Michigan 49224
3Department of Biological Sciences, P.O. Box 369, Galvin Life Science Center, University of Notre Dame, Notre Dame, IN 46556-0369.

Abstract

Rhagoletis fruit flies are important both as major agricultural pests and as model organisms for the study of adaptation to new host plants and host race formation. Response to fruit odor plays a critical role in such adaptation. To better understand olfaction in Rhagoletis, an expressed sequence tag (EST) study was carried out on the antennae and maxillary palps of Rhagoletis suavis (Loew) (Diptera: Tephritidae), a common pest of walnuts in eastern United States. After cDNA cloning and sequencing, 544 ESTs were annotated. Of these, 66% had an open reading frame and could be matched to a previously sequenced gene. Based on BLAST sequence homology, 9% (49 of 544 sequences) were nuclear genes potentially involved in olfaction. The most significant finding is a putative odorant receptor (OR), RSOr1, that is homologous to Drosophila melanogaster Or49a and Or85f. This is the first tephritid OR discovered that might recognize a specific odorant. Other olfactory genes recovered included odorant binding proteins, chemosensory proteins, and putative odorant degrading enzymes.

Keywords: host race, Juglans nigra, olfaction, odorant receptor, Rhagoletis, Tephritidae, speciation
Abbreviations: CSP, chemosensory protein; EST, expressed sequence tag; OBP, odorant binding protein; OR, odorant receptor

Correspondence: a ramsdell@life.uiuc.edu, b ssobaski@albion.edu, c hughrobe@uiuc.edu, d k-walden@life.uiuc.edu, e jfeder@nd.edu, f kwanner@life.uiuc.edu, g stewartb@life.uiuc.edu
Associate Editor: Zhijian Tu was editor of this paper

Received: 9 June 2008 | Accepted: 7 September 2008 | Published: 3 June 2010

ISSN: 1536-2442 | Volume 10, Number 51

Ramsdell KMM, Lyons-Sobaski SA, Robertson HM, Walden KKO, Feder JL, Wanner K, Berlocher SH. 2010. Expressed sequence tags from cephalic chemosensory organs of the northern walnut husk fly, Rhagoletis suavis, including a putative canonical odorant receptor . 11pp. Journal of Insect Science 10:51, available online: insectscience.org/10.51


Figure 1
Figure 2
Figure 3