Antioxidative enzyme activities in the leaves and callus tissues of salt-tolerant and salt-susceptible melon varieties under salinity

Abstract

The response of the antioxidant system to salt stress was studied in the leaves and callus tissues of 4 Turkish melon varieties (Cucumis melo L.) Besni, Yuva, Midyat, and Semame and a melon cultivar Galia C8. The antioxidant capability of the plants was determined by measuring superoxide dismutase (SOD) and catalase (CAT) activities. On the 8^th day of the salt stressed callus culture, growth reductions were observed in the weight of the callus in the salty medium compared to the control in all varieties. Salt treatment increased enzyme activities in stress-tolerant Galia C8, Midyat, and Semame. On the other hand, salt treatment did not cause a significant increase in SOD activity in the callus tissues of saltsensitive Yuva and moderately tolerant Besni. CAT activity increased in all of the genotypes grown under saline conditions compared with control calli. Increases in CAT activities were higher in salttolerant Galia C8 and Midyat than in all of the other varieties used in the callus culture. Data indicate that melon plants respond to salt-induced oxidative stress by increasing their enzymatic antioxidant defense systems. The results taken from the experiments with intact melon plants were obtained in the same manner as the callus culture.

Key words: Antioxidant, callus culture, Cucumis melo, enzyme, salt tolerance.