Determination of changes in antioxidant enzyme activities of some safflower (Carthamus tinctorius L.) varieties applied boric acid by ecophysiological parameters, physiological and molecular methods

Safflower (Carthamus tinctorius L.) is an essential industrial plant which belongs to the family Compositae. Twenty-five different wild type of Carthamus grows around the World and 8 of them are present in Turkey. Safflower, which is cultivated and has many area of use in Turkey has an important potential in the evaluation of marginal areas as it has high tolerance against some abiotic stress factors like drought and salinity. Ecological, physiological, molecular changes occur in plants with the change of ecological circumstances, and thus plants develop various defence mechanisms against the stress factors. This limits the product quality and quantity. In this study APX, CAT, GR and SOD activities belonging to the three different Safflower types which were applied boric acid in different concentrations (0, 5, 10, 15 mM) measured spectrophotometrically and the changes occurred in the expression levels of these enzymes were obtained by quantitative real-time PCR. Besides, % germination amounts, root/shoot length, root/shoot fresh-dry weight, biomass and seed vitality index based on changing concentrations. According to the results obtained from the ecophysiological parameters, it is found out that high boric concentration affected the early seedling stage in safflower varieties adversely. It was observed that SOD and APX enzyme activity is increased and CAT and GR enzyme activity is decreased based on the increasing concentrations in spectrophotometric measurements. When qRT-PCR results of the antioxidant enzymes reviewed, increase is observed in the gene expression level of APX and SOD in Dinçer variety, APX in Balcı variety and in all of the antioxidant enzymes studied in Remzibey variety. Remzibey variety is found out to have the highest antioxidant capacity to cope with oxidative stress caused by boric acid application at high concentrations, Balcı variety is found out to have the lowest antioxidant capacity to cope with oxidative stress caused by boric acid application at high concentrations. Dinçer variety is found out to be closer to Balcı in tolerance against boron.