Homologous promoter derived constitutive and chloroplast targeted expression of synthetic cry1Ac in transgenic chickpea confers resistance against Helicoverpa armigera

Abstract

The insecticidal crystal protein derived from gram positive soil bacterium Bacillus thuringiensis plays an important role in controlling lepidopteran infestation. The present study seeks to protect chickpea plants from Helicoverpa armigera infestation by over expressing cry1Ac. Homologous Ubiquitin and RuBisCO small subunit (rbcS) promoters were used to transcribe cry1Ac in transgenic chickpea both constitutively and in a tissue specific manner through Agrobacterium mediated transformation of chickpea var. ICCV89314. Expressed Cry1Ac was specifically targeted to the chloroplast rich tissues using transit peptide sequence. After monitoring transgene integration by Southern hybridization, transgenic chickpea lines were further analyzed by western blot, ELISA and insect bioassay. Expression of cry1Ac in chickpea under the control of above two promoters conferred a high level of protection against pod borer infestation, where chloroplast targeting system was found to be more efficient in controlling this particular devastating lepidopteran pest.