Genome-wide scans and transcriptomic analyses characterize selective
changes as a result of chlorantraniliprole resistance in Plutella
xylostella
Abstract
Pesticide resistance in insects is an example of adaptive evolution
occurring in pest species and is driven by the artificial introduction
of pesticide. The diamondback moth (DBM), Plutella xylostella L.
(Lepidoptera: Plutellidae), has evolved resistance to various
insecticides. Understanding the genetic changes underpinning the
resistance to pesticides is necessary to the implementation of pest
control measures. For this reason, we sequenced the genome of 6
resistant and 6 susceptible DBMs, and inferred the genomic regions of
greatest divergence between strains using two indices, Fst and θπ. Among
several genomic regions potentially related to insecticide-resistance, a
P450 gene, CYP6B6-like, was observed with significant divergence between
the resistant and susceptible strains, with, among other SNPs, a
missense mutation located near the substrate recognition site (SRS). To
characterize the relative effects of directional selection via
insecticide tolerance (‘strain’) as compared to acute exposure of
insecticide (‘treatment’), four pairwise comparisons were carried out
between libraries to determine the differentially expressed genes
(DEGs). Most resistant-related DEGs were identified from comparison
between strains, and enriched in pathways for exogenous detoxification
including cytochrome P450 and ABC transporter. Further confirmation came
from the weighted gene co-expression network analysis (WGCNA), which
indicated that genes in the significant module associated with
chlorantraniliprole-resistance were enriched in pathways for exogenous
detoxification, and that CYP6BG1 represented a hub gene in this module.
Our study thus provides a genetic foundation underlying selection for
pesticide resistance and plausible mechanisms to explain fast evolved
adaptation through genomic divergence and altered gene expression in
insects.