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