Cloning And Functional Analysis Of The Burscion Gene In Diamondback Moth, Plutella Xylostella

Bursicon is a neurohormone that regulates cuticle sclerotization (tanning andhardening) and the wing expansion processes in insects. Bursicon is actually aheterodimeric cystine knot family protein containing two subunits, bursicon α (burαor burs) and bursicon β (burβ or pburs), which are encoded by two individual genesbursα and bursβ (or burs and pburs). Although bursicon genes have been cloned fromseveral insect species or predicted from insect genomes, bursicon in diamond backmoth, Plutella xylostella,has not been reported.In this study, the burs α and burs β genes were cloned from P. xylostella using5’ and3’ rapid amplification of cDNA ends (RACEs). The full-length (537bp) cDNAof bursα gene is comprised of a18bp of5’ untranslated region (UTR),102bp of3’UTR, and an open reading frame (ORF) of357bps, encoding a119amino acid (a.a.)polypeptide with a predicted molecular weight of16.4kDa. The full-length (360bp)cDNA of the bursβ gene contains a36bp of5’ UTR,21bp of3’ UTR, and an ORF of303bps, encoding a101a.a. polypeptide with a predicted molecular weight of11.7kDa. The identities of P. xylostella bursα and bursβ with the bursicon sequencesfrom other insect species range from51%to68%and37%to57%, respectively.The bursα and bursβ gene expression at different developmental stages of P.xylostella have been investigated by the realtime PCR. Bursicon gene was expressedat a low level in larvae, a high level in pupae, and a low level again in adults. Then,we fed the double-stranded RNA of bursα on the4th-instar larvae. The results showedthat the expression of bursα mRNA was reduced significantly in pupae. The bursαgene expression was obviously inhibited in the12of the total16insect samples,account for75%. Accordingly, the growth and development of the diamondback mothwere seriously delayed, and pupae couldn’t normally emerge into adult, and then todeath. But this kind of phenomenon did not observed in the control group. In conclusion, bursicon plays a key role in the development of P. xylostella.