Miniature Inverted-Repeat Transposable Elements (MITEs) in the Two Lepidopteran Genomes of Helicoverpa armigera and Helicoverpa zea.

Abstract

Simple SummaryMiniature inverted-repeat transposable elements (MITEs) are non-autonomous transposable elements that play important roles in genome organization and evolution. Helicoverpa armigera and Helicoverpa zea shows a high number of reported cases of insecticide resistance worldwide, having evolved resistance against pyrethroids, organophosphates, carbamates, organochlorines, and recently to macrocyclic lactone spinosad and several Bacillus thuringiensis toxins. In the present study, we conducted a genome screening of MITEs in the H. armigera and H. zea genomes using bioinformatics approaches, and the results revealed a total of 3570 and 7405 MITE sequences in the H. armigera and H. zea genomes, respectively. Among these MITEs, we highlighted eleven MITE insertions in the H. armigera defensome genes and only one MITE insertion in those of H. zea.Miniature inverted-repeat transposable elements MITEs are ubiquitous, non-autonomous class II transposable elements. The moths, Helicoverpa armigera and Helicoverpa zea, are recognized as the two most serious pest species within the genus. Moreover, these pests have the ability to develop insecticide resistance. In the present study, we conducted a genome-wide analysis of MITEs present in H. armigera and H. zea genomes using the bioinformatics tool, MITE tracker. Overall, 3570 and 7405 MITE sequences were identified in H. armigera and H. zea genomes, respectively. Comparative analysis of identified MITE sequences in the two genomes led to the identification of 18 families, comprising 140 MITE members in H. armigera and 161 MITE members in H. zea. Based on target site duplication (TSD) sequences, the identified families were classified into three superfamilies (PIF/harbinger, Tc1/mariner and CACTA). Copy numbers varied from 6 to 469 for each MITE family. Finally, the analysis of MITE insertion sites in defensome genes showed intronic insertions of 11 MITEs in the cytochrome P450, ATP-binding cassette transporter (ABC) and esterase genes in H. armigera whereas for H. zea, only one MITE was retrieved in the ABC-C2 gene. These insertions could thus be involved in the insecticide resistance observed in these pests.