DIFFERENTIAL CHANGES IN ISOZYME PROFILES OF ANTIOXIDANT ENZYMES INDUCED BY PESTICIDES AND NEEM ALONE AND IN COMBINATION IN TOMATO PLANTS (LYCOPERSICON ESCULENTUM).

Changes in isozyme profiles of antioxidants SOD, CAT, APX, GPOX and GR in tomato plants under the effect of individual doses of two pesticides dimethoate (D1 = 0.1% and D2 = 0.2%) and cypermethrin (C1 = 0.03% and C2 = 0.06%) and biopesticide neem (N1 = 0.4%) as well as combined doses of dimethoate/cypermethrin and neem (D1+N1, D2+N1, C1+N1, C2+N1) were analysed through Native PAGE. Application of neem resulted in lower SOD and better CAT activity besides coordination among the activities of other antioxidants. Intensity of SOD bands increased whereas inhibition in CAT expression was observed with increasing pesticide doses suggesting higher production of O2-. SOD1 and SOD3 were found to be associated with dimethoate toxicity whereas SOD2 was linked with cypermethrin toxicity. Dimethoate stress inhibited APX enzyme expression whereas APX was sensitive to higher dose of Cypermethrin. An exclusive role of GPOX2 isozyme was found in total peroxidase activity in tomato plants. GPOX was found to be more sensitive to dimethoate whereas GR was found to be more sensitive to Cypermethrin. At combined doses, low intensity SOD bands and high CAT activity band was observed which might be associated with lower generation and higher detoxification of O2-. Further, activities of APX, GPOX and GR were also found to be coordinated and stable at combined doses exhibiting enhancement in antioxidant capacity in tomato plants due to supplementation of neem.