P450 knockdown by RNA interference enhances fenvalerate susceptibility of H. armigera

What is it about?

The function of cytochrome P450 proteins in the metabolism of a variety of compounds is well elucidated, but its interactions with other electron transfer components in the pyrethroid resistance of insect pests have been a mystery for a long time. In previous studies, we cloned and characterised CYP6B7 and cytochrome b5 in the fenvalerate-resistant HDFR strain of cotton bollworm and showed that CYP6B7 mRNA was overexpressed and important for resistance to fenvalerate. Here, the functional interactions of CYP6B7, NADPH-dependent cytochrome P450 reductase and Cyt-b5 were assessed using RNA interference strategies and monitoring for fenvalerate resistance levels.

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Why is it important?

RT-qPCR analyses indicated that the expression levels of CYP6B7, CPR and Cyt-b5 mRNA were decreased drastically in the midgut of 4th-instar larvae of HDFR strain after corresponding double-stranded RNA injection, compared with that of the control. The knockdown of CYP6B7, CPR and Cyt-b5 transcripts was time course dependent during a 12–48 h period after dsRNA injection. At the earlier time points analysed, significant suppression of CYP6B7 mRNA levels was observed in larvae injected with dsCYP6B7-313 as compared with controls, and further suppression was observed in larvae injected with dsCYP6B7-313, dsCPR-403 and dsCyt-b5. The injection of dsCYP6B7-313 together with dsCPR-403 and dsCyt-b5 increased larval susceptibility of the HDFR strain to fenvalerate.

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