|GEIB, SCOTT - Hawaii Agricultural Research Center|
|WALSH, DOUGLAS - Washington State University|
|LAVINE, LAURA - Washington State University|
|CHANEY, KENDRICK - South Mountain Community College (SMCC)|
Submitted to: PLoS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2014
Publication Date: 11/17/2014
Publication URL: http://handle.nal.usda.gov/10113/59983
Citation: Hull, J.J., Chaney, K., Geib, S.M., Fabrick, J.A., Brent, C.S., Walsh, D., Lavine, L.C. 2014. Transcriptome-based identification of ABC transporters in the western tarnished plant bug Lygus hesperus. PLoS ONE. 9(11):e113046.
Interpretive Summary: The western tarnished plant bug is an important pest of numerous crops in the western United States. Despite its economic importance, little is known about how the genetics (collection of genes) of the western tarnished plant bug influences its growth, development, and interactions with the environment. When a given gene is active, or expressed, it produces a chemical sequence (a transcript) that provides information to produce a protein product, perform a function, or provide a signal within the insect cell. The collective transcripts (a transcriptome) at a given time, age, or within a given organ or tissue reflects the specific genes that are expressed. The ABC transporters are a set of proteins found in all organisms that play a number of important roles, including transport and elimination of toxicants. This function has been linked with the development of resistance to insecticides in some insects. To better understand the function of ABC transporters in the western tarnished plant bug, we searched the adult transcriptome for sequences typical of ABC transporters. Our search identified 65 ABC transporter transcripts, none of which were previously known from this insect. Based on comparisons with transcripts of other organisms, we assigned likely functions to most of the transcripts. A subset of the transcripts was found in tissues associated with detoxification and reproduction. Further exploration of these genes may provide clues regarding the mechanisms by which the western tarnished plant bug detoxifies or eliminates insecticides, and how its reproductive development is regulated. Our findings provide base-line information to better document the underlying genetics of the western tarnished plant bug. This knowledge is essential to fully understand how this pest interacts with its agricultural environment, and will facilitate the development of improved biologically-based management strategies.
Technical Abstract: ATP-binding cassette (ABC) transporters are a large superfamily of proteins that mediate diverse physiological functions by coupling ATP hydrolysis with substrate transport across lipid membranes. In insects, these proteins play roles in metabolism, development, eye pigmentation, and xenobiotic clearance. While ABC transporters have been extensively studied in vertebrates, less is known concerning this superfamily in insects, particularly hemipteran pests. We used RNA-Seq transcriptome sequencing to identify 65 putative ABC transporter sequences (including 36 full-length sequences) from the eight ABC subfamilies in the western tarnished plant bug (Lygus hesperus), a polyphagous agricultural pest. Phylogenetic analyses revealed clear orthologous relationships with ABC transporters linked to insecticide/xenobiotic clearance and indicated lineage specific expansion of the L. hesperus ABCG and ABCH subfamilies. The transcriptional profile of 13 LhABCs representative of the ABCA, ABCB, ABCC, ABCG, and ABCH subfamilies was examined across L. hesperus development and within sex-specific adult tissues. All of the transcripts were amplified from both reproductively immature and mature adults and all but LhABCA8 were expressed to some degree in eggs. Expression of LhABCA8 was spatially localized to the testis and temporally timed with male reproductive development, suggesting a potential role in sexual maturation and/or spermatozoa protection. Elevated expression of LhABCC5 in Malpighian tubules suggests a possible role in xenobiotic clearance. Our results provide the first transcriptome-wide analysis of ABC transporters in an agriculturally important hemipteran pest and, because ABC transporters are known to be important mediators of insecticidal resistance, will provide the basis for future biochemical and toxicological studies on the role of this protein family in insecticide resistance in Lygus species.