Determination of Antioxidative Enzyme Activities in Callus Culture of the Salt-Tolerant and Salt-Sensitive Watermelon (Citrullus Lanatus (Thunb.) Mansf.) Genotypes Under Salt Stress

Abstract

To investigate the antioxidant defense system, salt stress induced changes in antioxidant enzymes activities were examined in the callus of salttolerant (Diyarbaki{dotless}r and Midyat local genotype), and salt-sensitive (Golden Crown F1 and Crimson Sweet) watermelon (Citrullus lanatus) varieties. On the 6th and 12th days of salt stress, the callus weights were higher in Golden Crown F1 (GCF1) and Crimson Sweet (CRS) than Diyarbaki{dotless}r (DİB) and Midyat (MİD) genotypes. When compared to control, salt treatment decreased significantly callus growth in salt-sensitive GCF1 and CRS, but did not in salt-tolerant DİB and MİD. Salt treatment increased significantly SOD, CAT, GR and APX enzyme activities in all varieties compared to control treatment. On the other hand, the increases were higher in salt-tolerant DİB and MİD than salt-sensitive GCF1 and CRS. These results possibly suggest that the antioxidant enzyme activities play an active role against stress, the tolerance levels against salt stress in callus culture can be utilized as effective criteria in the genotypes of watermelon. The salt-tolerant genotypes exhibited a better protection mechanism response of salt stress by maintaining a higher inherited and induced activity of antioxidant enzymes than the sensitive genotypes.