Cloning and characterisation of NADPH-dependent cytochrome P450 reductase gene in the cotton bollworm, Helicoverpa armigera.

BACKGROUND

Previous studies in our laboratory showed that cytochrome P450 CYP6B7 plays a critical role in a Handan fenvalerate resistant strain (HDFR) of Helicoverpa armigera. As an important component of P450 enzyme systems, cytochrome P450 reductase (CPR) plays an essential role in transferring electrons from NADPH to the P450-substrate complex. However, little information about CPR in H. armigera (HaCPR) has been reported.

RESULTS

A full-length cDNA (3525 bp) of HaCPR was cloned. The open reading frame of the HaCPR gene encoded 687 amino acids and shared 27.87-95.21% identities with other known CPRs. Bioinformatic analysis showed that HaCPR is a transmembrane protein with Mw of 77.4 kDa and contains conserved features. The results of real-time quantitative polymerase chain reaction showed that the expression level of HaCPR mRNA was 1.84-fold higher in midgut of 5th instars of the Handan susceptible strain than that in pupae, and the level in the midgut of HDFR strain was 2.02-fold higher than that of the Handan susceptible strain. The levels of HaCPR mRNA were induced by phenobarbital at concentrations of 2 and 4 mg g(-1) , which enhanced 5.20- and 17.45-fold, respectively, compared to that of the control after 48 h of phenobarbital treatment.

CONCLUSIONS

The results indicate that HaCPR is important for the development of H. armigera and may play an essential role in the P450-mediated insecticide resistance of H. armigera to fenvalerate.