Modulation of the expression of ryanodine receptor mRNA from Plutella xylostella as a result of diamide insecticide application.

Ryanodine receptors (RyRs), members of the largest family of calcium channel proteins, have been studied because of their key roles in calcium signalling within cells. With the development of diamide insecticides that exhibit a novel mode of action on the RyRs from Lepidoptera, research on insect RyRs has become more attractive in the field of plant protection. To enhance our understanding of the effects of diamides on RyRs, we cloned the Plutella xylostella RyR gene (Px-RyR), which is the most serious pest of Brassicaceae plants throughout the world. Furthermore, we investigated the modulation of the expression of Px-RyR as a result of the application of diamide insecticides. The full-length cDNAs of Px-RyR contain an open reading frame (ORF) of 15,372bp with a predicted protein consisting of 5123 amino acids. Px-RyR possesses a high level of overall amino acid homology with other isoforms (77-92% identity with insect isoforms and 45-47% identity with vertebrate isoforms). The weight of Px. gradually decreased as the concentration of the diamides increased. However, the relative expression levels of the RyRs from larvae were dependent on the insecticide concentration and gradually increased with increasing insecticide concentrations.