Genomic Insights into the Glutathione S-Transferase Gene Family of Two Rice Planthoppers, Nilaparvata lugens (Stål) and Sogatella furcifera (Horváth) (Hemiptera: Delphacidae)

Abstract

BackgroundGlutathione S-transferase (GST) genes control crucial traits for the metabolism of various toxins encountered by insects in host plants and the wider environment, including insecticides. The planthoppers Nilaparvata lugens and Sogatella furcifera are serious specialist pests of rice throughout eastern Asia. Their capacity to rapidly adapt to resistant rice varieties and to develop resistance to various insecticides has led to severe outbreaks over the last decade.Methodology/Principal FindingsUsing the genome sequence of N. lugens, we identified for the first time the complete GST gene family of a delphacid insect whilst nine GST gene orthologs were identified from the closely related species S. furcifera. Nilaparvata lugens has 11 GST genes belonging to six cytosolic subclasses and a microsomal class, many fewer than seen in other insects with known genomes. Sigma is the largest GST subclass, and the intron–exon pattern deviates significantly from that of other species. Higher GST gene expression in the N. lugens adult migratory form reflects the higher risk of this life stage in encountering the toxins of non-host plants. After exposure to a sub-lethal dose of four insecticides, chlorpyrifos, imidacloprid, buprofezin or beta-cypermethrin, more GST genes were upregulated in S. furcifera than in N. lugens. RNA interference targeting two N. lugens GST genes, NlGSTe1 and NlGSTm2, significantly increased the sensitivity of fourth instar nymphs to chlorpyrifos but not to beta-cypermethrin.Conclusions/SignificanceThis study provides the first elucidation of the nature of the GST gene family in a delphacid species, offering new insights into the evolution of metabolic enzyme genes in insects. Further, the use of RNA interference to identify the GST genes induced by insecticides illustrates likely mechanisms for the tolerance of these insects.

Rhodnius prolixus supergene families of enzymes potentially associated with insecticide resistance

“…org/), AphidBase (http://www.aphidbase.com/) and Hymenoptera Genome Database (http://hymenopteragenome.org/). For the GSTs, genes with classification obtained from other three hemipterans, taken from the work of Zhou et al (2013), were also used. To search the R. prolixus genome for microsomal and kappa GSTs, already annotated sequences from human, Ac.…”

“…Phylogenetic relationship of 161 cytosolic GST genes from R. prolixus and other seven insect species. Genes from N. lugens, S. furcifera and L. striatellus taken from Zhou et al (2013). Neighbor-joining tree based on amino acid MAFFT alignment with JTT scoring matrix.…”

Application of Virus-Derived Small Interfering RNAs (vsiRNAs) in Rice Viruses with Insect Vectors, Especially <em>Rice Grassy Stunt Virus</em>

“…Two species of N. lugens were targeted by RNAi, GSTe1, and GSTm2 that significantly increased the fourth-star nymph's sensitivity to pesticide chlorpyriphos [130]. Enolase gene (Eno1) silencing revealed down-regulation of mRNA level significantly in N. lugens and also decreased the egg laying capacity and population size during next generation of the planthopper [100].…”

Resistensi Wereng Batang Cokelat Padi, Nilaparvata lugens Stål terhadap Insektisida di Indonesia

“…Data sekuen genom WBC menunjukkan bahwa WBC mempunyai 11 gen GST yang mengkode enzim GST. Penggunaan RNAi yang ditargetkan untuk mengganggu ekspresi dua gen GST dalam WBC (NlGSTe1 dan NlGSTm2), secara nyata dapat menaikkan sensitivitas nimfa instar keempat terhadap insektisida klorpirifos tetapi tidak terhadap beta-sipermetrin (Zhou et al, 2013). Dengan demikian gen NlGSTe1 dan NlGSTm2 berperan dalam mengkode enzim GST yang mendetoksifikasi insektisida klorpirifos.…”