Relationship between antioxidant defence systems and salt tolerance in Solanum tuberosum

A relationship between the antioxidant defence system and salt tolerance in two clones of potato (Solanum tuberosum L.) differing in salt sensitivity was studied. The antioxidant defence system of the sensitive clone responde d differently to 100 and 150 mM NaCl. At 100 mM NaCl, growth, dehydroascorb ate reductase and catalase activities remained unaltered, but chlorophyll a nd reduced glutathione content decreased (23% and 35%, respectively), while ascorbate content and superoxide dismutase activity were increased 34% and 63%, with respect to the control (0 mM NaCl). The superoxide dismutase inc rement was higher under 150 mM NaCl treatment, while a general decrease (ex cept for dehydroascorbate reductase and catalase activities) in all the ant ioxidant parameters studied was observed in the sensitive clone. Reduced gl utathione and ascorbate, the main antioxidant soluble defences, and all ant ioxidant enzymes (except catalase) were significantly elevated in the toler ant clone compared to the sensitive one when both were grown in the absence of NaCl. Under 100 and 150 mM NaCl treatments, no changes in the antioxida nt stress parameters were detected in the tolerant clone. These results sug gest a relationship between salt tolerance and the antioxidant defence syst em in the two clones.