Glutathione S-transferase (GST) genes in the red flour beetle, Tribolium castaneum, and comparative analysis with five additional insects

Glutathione S-transferases are important detoxification enzymes involved in insecticide resistance. Sequencing the Tribolium castaneum genome provides an opportunity to investigate the structure, function, and evolution of GSTs on a genome-wide scale. Thirty-six putative cytosolic GSTs and 5 microsomal GSTs have been identified in T. castaneum. Furthermore, 40, 35, 13, 23, and 32 GSTs have been discovered the other insects, Drosophila, Anopheles, Apis, Bombyx, and Acyrthosiphon, respectively. Phylogenetic analyses reveal that insect-specific GSTs, Epsilon and Delta, are the largest species-specific expanded GSTs. In T. castaneum, most GSTs are tandemly arranged in three chromosomes. Particularly, Epsilon GSTs have an inverted long-fragment duplication in the genome. Other four widely distributed classes are highly conserved in all species. Given that GSTs specially expanded in Tribolium castaneum, these genes might help to resist poisonous chemical environments and produce resistance to kinds of different insecticides.

► 183 GSTs have been discovered in six model insects. ► Insect-specific GSTs, Epsilon and Delta, have largely expanded in insects. ► Epsilon GSTs have a specifically inverted long-fragment duplication in T. castaneum. ► The most conservative GST classes in insects are Zeta and Theta.