Location: Corn Insects and Crop Genetics ResearchTitle: Genome-wide sequencing and an open reading frame analysis of dichlorodiphenyltrichloroethane (DDT) susceptible (91-C) and resistant (91-R) Drosophila melanogaster laboratory populations) Author
|Seong, Keon Mook|
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2014
Publication Date: 6/10/2014
Citation: Steele, L.D., Muir, W.M., Seong, K., Quiros, C., Rangesa, M., Clark, J.M., Coates, B.S., Pittendrigh, B.R. 2014. Genome-wide sequencing and an open reading frame analysis of dichlorodiphenyltrichloroethane (DDT) susceptible (91-C) and resistant (91-R) Drosophila melanogaster laboratory populations. PLoS One. 9(6):e98584. Interpretive Summary: Insect resistance to chemical insecticides remains a threat to sustainability of agricultural production and human health in the United States and worldwide. The fruit fly species, Drosophila melanogaster, was used as a model to understand how selection for survival, when exposed to chemical insecticides in the laboratory, affects genome structure and function. Specifically, fruit fly resistance to the chemical insecticide dichlorodiphenyltrichloroethane (DDT) have become models for the study of evolving resistance traits in insect populations, and can translate the resistance traits observed in many crops pest species. Questions remain about the origin of mutations that give rise to resistance traits in insect populations. In this study, the origin of mutations in the 91-R strain of DDT resistant fruit flies which were linked to DDT resistance are shown to be new. That is, these mutations have not been observed previously in the extensive genome resources for fruit fly, and evolve at a rate much greater compared to flies not exposed to insecticides. This information suggests that exposure to chemical insecticides may increase the rate at which new mutations accumulate, and will be useful for government, university and private sector scientists that investigate insect resistance and who are concerned with durability of current insecticide chemistries used in agricultural production.
Technical Abstract: The Drosophila melanogaster 91-R and 91-C strains are of common origin, however, 91-R has been intensely selected for dichlorodiphenyltrichloroethane (DDT) resistance over six decades while 91-C has been maintained as the non-selected control strain. These fly strains represent a unique genetic resource to understand the accumulation and fixation of mutations under laboratory conditions over decades of pesticide selection. Considerable research has been done to investigate the differential expression of genes associated with the highly DDT resistant strain 91-R, however, with the advent of whole genome sequencing we can now begin to develop an in depth understanding of the genomic changes associated with this intense decades-long xenobiotic selection pressure. Here we present the first whole genome sequencing analysis of the 91-R and 91-C fly strains to identify genome-wide structural changes within the open reading frames. Between-strain changes in allele frequencies revealed a higher percent of new alleles going to fixation for the 91-R strain, as compared to 91-C (P < 0.0001). These results suggest that resistance to DDT in the 91-R laboratory strains could potentially be due primarily to new mutations, as well as being polygenic rather than the result of a few major mutations, two hypotheses that remain to be tested.