Molecular characterization and expression pattern of four chemosensory proteins from diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae).

Some chemosensory proteins (CSPs) expressed in insect sensory appendages are thought to be involved in chemical signaling in moths. We cloned and characterized four CSP genes from Plutella xylostella. The deduced amino acid sequences of PxylCSP1, PxylCSP2, PxylCSP3 and PxylCSP4 revealed open reading frames of 152, 128, 126 and 126 amino acids, respectively, with four conserved cysteine residues. The expression patterns of the four PxylCSP genes were further investigated by reverse transcription (RT) PCR and real-time PCR. PxylCSP1 and PxylCSP2 genes were expressed in all the tested tissues with the highest expression level in the antennae and heads (without antennae) whereas PxylCSP3 and PxylCSP4 mRNA were distributed extensively in all the tested tissues without apparent quantitative differences. The transcription levels of these CSP genes depended on sex, age, mating and the genes. Fluorescence quenching with Rhodojaponin-III (R-III) and homology modelling studies indicated that PxylCSP1 was able to bind non-volatile oviposition deterrents, such as R-III. These ubiquitous proteins might have the role of extracting non-volatile compounds (oviposition deterrents or antifeedants) dispersed in the environment and transporting them to their receptor.