Cry1Ac protein (endotoxin) produced in Bt transgenic cotton is effective in controlling Helicoverpa armigera. In the present study the new event of transgenic Bt cotton of UAS Dharwad (Katageri et al, 2006) was monitored for endotoxin expression in 5 genotypes in two tissues at different growth stages. RCH-2 Bt and MRC-6918 of Mon 531 included as checks.
            Analysis of variance indicated a significant difference between genotypes, growth stages and tissues for the expression of endotoxin protein and their interaction effect was also significant. Irrespective of growth stages and tissues, the genotypes (BN Bt, NHH 44, DBT-H1 and DBT-H2) developed, out of new University of Agricultural Sciences, Dharwad event expressed significantly higher amount of endotoxin than RCH-2 Bt and MRC-6918 of Mon 531 event. Presence of interaction effect between genotype and tissues for expression of endotoxin was evident in the study as the highest and significantly different expression was noticed in leaves of DBT-H2, lowest expression was noticed in fruiting bodies of RCH-2 Bt which was significantly lower than fruiting bodies of BN Bt and DBT-H2.