Structural and functional insights into the Diabrotica virgifera virgifera ATP-binding cassette transporter gene family

Authors: ADEDIPE, FOLUKEMI - North Carolina State University; GRUBBS, NATANIEL - North Carolina State University; Coates, Brad; WIEGMMAN, BRIAN - North Carolina State University; LORENZEN, MARCE - North Carolina State University

Submitted to: BMC Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/22/2019
Publication Date: 11/27/2019
Citation: Adedipe, F., Grubbs, N., Coates, B.S., Wiegmman, B., Lorenzen, M. 2019. Structural and functional insights into the Diabrotica virgifera virgifera ATP-binding cassette transporter gene family. BMC Genomics. 20. https://doi.org/10.1186/s12864-019-6218-8.
DOI: https://doi.org/10.1186/s12864-019-6218-8

Interpretive Summary: The Western corn rootworm (WCR) is a major insect pest that causes damage to cultivated corn across the Midwest United States. The evolution of resistance to multiple Bacillus thuringiensis (Bt) toxins by WCR threatens the sustainability of current corn production practices. While Bt resistance mechanisms in WCR are unknown, the members of the ATP-binding cassette (ABC) transporter gene family have been implicated in Bt resistance in other crop pest species. Studying the genetic mechanisms underlying Bt resistance in WCR have been hampered by a relative lack of genomic sequence data and an understanding of gene function. To partially address this, a USDA scientist at the Corn Insects and Crop Genetics Research Unit in Ames, Iowa, and collaborators from North Carolina State University generated WCR sequence data for all genes active across adult (beetle), larval, and embryonic growth stages. This data was mined to identify to sixty-five unique ABC tranporters, representing eight subfamilies. Gene knock-down technology (RNAi) was used to identify ABC transporters involved in female fecundity (fertility) and egg production. The sequence data from this study will be useful in future studies to define the role of ABC transporters in the evolution of Bt toxin resistance in WCR. In addition, the novel RNAi knockdown phenotypes within female reproductive capacity may prove useful for future efforts to suppress WCR populations. This research is of interest to public and private sector scientists involved in the genomics of crop pest insects and those investigating Bt resistance mechanisms.

Technical Abstract: The western corn rootworm, Diabrotica virgifera virgifera, is a pervasive pest of cultivated maize in North America and Europe, which has adapted to survive exposure to multiple insecticidal agents. Members of the ATP-binding cassette (ABC) transporter family play diverse cellular roles in arthropods, including xenobiotic detoxification. In this study, 65 putative D. virgifera virgifera ABC transporterswere identified within a combined transcriptome assembly generated from four growth stage-specific RNA-seq libraries (embryo, larvae, adult male, and adult female. Phylogenetic analysis placed derived ABC transporters peptides into eight subfamilies (DvvABCA to DvvABCH). Functional conservation was shown for 8 DvvABC transporters with obvious RNA interference (RNAi) knockdown phenotypes among direct Tribolium castaneum orthologs, following RNAi knockdown in D. virgifera virgifera. Interestingly, depletion of DvvABCB_19147 and DvvABCG_3712 transcripts in adult females produced detrimental reproductive and developmental phenotypes (egg-laying and -hatching defects), demonstrating their potential as insect control targets. This study provides insights into the developmental and physiological roles of D. virgifera virgifera ABC transporters and suggests candidate target sites for the development of novel insect control tactics.