Antioxidant enzymes and membrane lipid composition of disease resistant tomato plants regenerated from crown galls

Inhibition of senescence of plants increases their resistance to necrotroph ic pathogens and to many abiotic stresses. Tomato plants regenerated from t umors induced by Agrobacterium tumefaciens T37 strain showed higher degree of tolerance to Phytophthora infestans infection. As regards the mechanism of the enhanced resistance to necrosis, increased phospholipid and galactol ipid contents, in addition to decreased free sterols in the transformed pla nts gave greater stability to their membranes as compared to membranes from control plants. In addition, the elevated activity of some antioxidant enz ymes such as superoxide dismutase and catalase in transformed tissues can a lso play a significant role in the. tolerance to pathogenic and abiotic str esses.