Abstract:

According to the homologous amino acid sequences in Caenorhabditis elegans and other insects, the full length cDNA sequences of 3 glycosyltransferase genes (named as Pxbre-3, Pxbre-4 and Pxbre-5) were cloned by RT-PCR and RACE-PCR from the midgut of 4th instar larvae of the diamondback moth, Plutella xylostella. The open reading frames of these genes were 1 383 bp, 1 230 bp and 1 041 bp, respectively. The deduced coding products had 460, 409 and 346 amino acids, respectively. These genes were homologous to the bre genes of Caenorhabditis elegans and had the predicted membrane-spanning regions and conserved motifs known to play key catalytic roles in glycosyltransferases. Thus, the three genes are inferred to code glycosyltransferases in P. xylostella. The mRNA expression of these three genes and Pxbre-2 was detected in different developmental stages (larva, pupa, and adult) of P. xylostella by real-time quantitative PCR, and the expression level was higher in pupa and adult. These results provide an important basis for investigating the possible involvement of glycosylphingolipid in resistance to Cry toxins in P. xylostella.

Key words: Plutella xylostella, Cry toxin, glycosylphingolipid, glycosyltransferase, mRNA expression