Expression of Bt Gene (cry1Ac) on Different Plant Parts at Different Stages in Bt Cotton Genotypes

Cotton yield losses due to insect pests are estimated to be around 10 to 14 per cent every year. These insect protected cotton varieties contain a naturally occurring substance, Bacillus thuringiensis (Bt) protein which has been used as an ingredient in safe and effective biological sprays for more than 50 years. Of the total available Bt cotton hybrids in 2006, four different events containing Cry1Ac gene (MON 531 event) by Mahyco sourced from Monsanto, stacked Cry X (Cry1Ac and Cry2Ab) gene event (MON 15985) developed by Mahyco sourced from Monsanto, Cry1Ac gene (Event 1) by JK-seeds sourced from IIT Kharagpur and fusion gene Cry1Ab and Cry1Ac (GF Mervent) by Nath seeds sourced from China have received commercial approval for sale in Northern, Central and Southern cotton growing zones. The expression of Bt gene varies with different parts of plant. The Cry 1 Ac gene expression highest in leaf (4.31 mg/g at 45 DAS) followed by young boll (2.02 mg/g at 105 DAS), flower (> 1.9 mg/g 105 DAS), seeds (1.9 mg/g 120 DAS and 1.49 mg/g at 160 DAS and least in rind (0.63 mg/g 105 DAS).