Expression of v-cath gene from HearNPV in tobacco confers an antifeedant effect against Helicoverpa armigera

Biotechnology solutions for insect control on crops largely depend on the expression of Bacillus thuringiensis insecticidal proteins to kill pests. V-CATH, a cathepsin L-like cysteine protease from baculoviruses, has been shown to play an essential role in host insect liquefaction. In this study, the v-cath gene from Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) was cloned into the pBI121 binary vector under the control of CaMV35S promoter, and was expressed in tobacco via Agrobacterium-mediated transformation. PCR and RT-PCR analyses of T1 kanamycin-resistant tobacco progeny plants confirmed the integration and transcription of the v-cath gene. Using a leaf-disk bioassay, antifeedant activity toward H. armigera was tested. Our result showed that, when feeding the first-instar larvae of H. armigera with leaves of transgenic plants, the v-cath transgene expression has a profound antifeedant effect. Most importantly, the growth and development of the insect were inhibited when transferred from leaf-feeding to artificial diet. Our result demonstrated that v-cath gene from baculovirus induced antifeedant effect against H. armigera, resulted in larval stunting and retarded insect development, and has the potential to be used as an alternative way to generate transgenic plants for insect pest control.