Analysis of the Olive Fruit Fly Bactrocera oleae Transcriptome and Phylogenetic Classification of the Major Detoxification Gene Families

Abstract

The olive fruit fly Bactrocera oleae has a unique ability to cope with olive flesh, and is the most destructive pest of olives worldwide. Its control has been largely based on the use of chemical insecticides, however, the selection of insecticide resistance against several insecticides has evolved. The study of detoxification mechanisms, which allow the olive fruit fly to defend against insecticides, and/or phytotoxins possibly present in the mesocarp, has been hampered by the lack of genomic information in this species. In the NCBI database less than 1,000 nucleotide sequences have been deposited, with less than 10 detoxification gene homologues in total. We used 454 pyrosequencing to produce, for the first time, a large transcriptome dataset for B. oleae. A total of 482,790 reads were assembled into 14,204 contigs. More than 60% of those contigs (8,630) were larger than 500 base pairs, and almost half of them matched with genes of the order of the Diptera. Analysis of the Gene Ontology (GO) distribution of unique contigs, suggests that, compared to other insects, the assembly is broadly representative for the B. oleae transcriptome. Furthermore, the transcriptome was found to contain 55 P450, 43 GST-, 15 CCE- and 18 ABC transporter-genes. Several of those detoxification genes, may putatively be involved in the ability of the olive fruit fly to deal with xenobiotics, such as plant phytotoxins and insecticides. In summary, our study has generated new data and genomic resources, which will substantially facilitate molecular studies in B. oleae, including elucidation of detoxification mechanisms of xenobiotic, as well as other important aspects of olive fruit fly biology.

Genomic features of the fall armyworm (Spodoptera frugiperda) (J.E. Smith) yield insights into its defense system and flight capability

“…P450s are one of the main classes of enzymes involved in lepidopteran resistance to insecticides, such as pyrethroids (Brun‐Barale et al ), organophosphates (Carvalho et al ) and diamides (Lin et al ). P450s have been detected in many insect genomes (do Nascimento et al ; Pavlidi et al ), which can be divided in four major clades (i.e. CYP2, CYP3, CYP4 and mitochondrial).…”

“…Previous studies have indicated that members of the CYP3 and CYP4 clades were most commonly involved in environmental response/detoxifying functions against xenobiotics and phytotoxins in insects (Pavlidi et al ; Berenbaum ). Thus, the overrepresentation of members of CYP3 and CYP4 clades indicated that the defense system against such compounds in FAW was possibly enhanced.…”

Transcriptome landscape of the developing olive fruit fly embryo delineated by Oxford Nanopore long-read RNA-Seq

“…We thus argue that the current B. oleae number of genes is underestimated, and our transcriptome provides over 3000 novel genes towards completing the annotation of the genome. Pavlidi et al, [34] previously generated a transcriptome assembly of the olive fly and assembled a total of 14,204 contigs. However, they used a short-read sequencing technology (454 pyrosequencing) and the average contig length was 421 bp compared to an average of 9000 bp in our transcriptome and 9,597 in the NCBI predicted gene models.…”

A review of plant protection against the olive fly (Bactrocera oleae (Rossi, 1790) Gmelin) and molecular methods to monitor the insecticide resistance alleles

“…A whole transcriptome analysis of spinosad susceptible and resistant flies indicated that several immune system loci as well as elevated energy requirements of the resistant flies might be necessary to lever the detoxification process (Efthimia et al, 2014). Pavlidi et al (2013) studied B. oleae mRNA and identified at least 132 putative major detoxification genes involved in the metabolism of xenobiotics, such as plant phytotoxins and insecticides.…”