The investigation of effects of nitric oxide application on the antioxidant system of salt stress-resistant and sensitive (Helianthus annuus L.) sunflower plants

In this study, the effects of externally applied sodium nitroprusside (SNP) on superoxide dismutase (SOD), glutathione peroxidase (GPx), ascorbate peroxidase (APX), and catalase (CAT) antioxidant enzyme activities, nitric oxide (NO) levels, relative water contents, and total protein quantities have investigated in salt stress-resistant (Helianthus annuus L. A-6535) and sensitive (Helianthus annuus L. A-2517) sunflower plants. Salt stress was generated by treating sodium chloride (NaCl) application to sunflower plants in the study. NaCl applications (100, 200 and 400 mM), SNP (100 µM) application, SNP applications simultaneous with salt application (NaCl+SNP) were performed. Control group also was grown in Hoagland culture solution. Leaf samples were collected from 2. and 4. day applications. At the end of the study, it was determined that SOD, GPx, APX and CAT antioxidant enzyme activities, NO levels, relative water contents, and amounts of total soluble protein showed differences according as days and application groups in leaf tissues treated 100 µM SNP, NaCl in different concentrations, and NaCl+SNP. In our study, it was seen that SOD, GPx and APX enzyme activities was generally increased in A-2517 type, but decreased in A-6535 type. However, while generally increase in CAT enzyme activity was determined in A-6535 type, a reduction was established in A-2517 type. An increase was determined in both types in NO levels. It was determined that relative water contents showed difference according as days and application groups. While a decrease was occurred in amount of soluble protein in A-2517 type, it was determined that it showed difference according as application groups in A-6535 type. It was established that both of types were also coped with formation of reactive oxygen species (ROS) by the NO transmitter SNP application with reference to this consequences.