The transgenic cotton expressing Bacillus thuringiensis (Bt)insecticidal crystal protein is being commercialized in a large scale in China.Several important isoenzymes,including Peroxidases(POD),Polyphenoloxidases(PPO)and Esterases(EST),were compared between two Bt cotton lines and regular cotton.The activity of Peroxidase in Bt cotton was higher than that in regular cotton.There were also diferences between Bt cotton and regular cotton in the Electrophoretic Patterns of Peroxidase and the activity of Es...