EFFECT OF PARAQUAT ON TRE SUPEROXIDE DISMUTASE AND CATALASE ACTIVITY OF TOMATO PLANTS SUSCEPTIBLE AND RESISTANT TO MELOIDOGYNE INCOGNITA
AbstractParaquat applied to tomato seedlings as aqueous solution or to tomato root culture incorporated in agar Gamborg's medium, affected the plant growth. Seedlings of the cultivars Roma VF and VFN8, susceptible and resistant to the root-knot nematode Meloidogyne incognita, respectively, wilted when supplied with more than 10 µM paraquat (PQ). Tomato roots grown in a medium containing more than 5 µM PQ ceased growing and became necrotic. The activities of two related enzymes, superoxide dismutase and catalase, were followed in seedlings and cultured tomato roots treated with different PQ concentrations. Paraquat caused a pronounced increase in the activity of superoxide dismutase and catalase. The changes in enzymatic activity appeared to result tram enzyme activation which was an adaptive response to provide protection against the herbicide.