Transgenic chickpeas (Cicer arietinum L.) expressing a sequence-modified cry2Aa gene

A cry2Aa gene with a sequence-modified open reading frame encoding an insecticidal crystal protein from Bacillus thuringiensis was introduced into chickpea (Cicer arietinum L.) to confer resistance to Helicoverpa armigera (pod borer). We used a twin T-DNA binary vector containing the nptII gene for selection and a chimeric cry2Aa gene driven by Arabidopsis small subunit gene (ats1A) promoter. Of the fifteen nptII positive lines established, thirteen accumulated Cry2Aa toxin in the leaves of T0 plants and five transmitted the cry2Aa gene to the next generation consistent with a 3:1 segregation. Western analysis of different organs showed high levels of Cry2Aa protein in all the green parts as well as in petals and cotyledons. Phenotypic data showed reduced productivity in two high expressing lines when compared to the parental line and lines with moderate expression levels. Insect bioassays using the progeny of selected lines showed differential resistance to pod borer larvae, depending upon the level of expression of the Cry2Aa protein. A high expressing line was found to confer near complete protection against the pod borer. We concluded that a sequence-modified cry2Aa gene expressed in chickpea is effective against pod borer larvae however accompanying reduction in productivity needs further investigation.