Antioxidant enzymes activity and membrane thermostability in durum wheat genotypes under heat stress

Relevance. Insufficient tolerance to extremely high temperatures is one of the main reasons for the decline in crop yields. Methods. Two contrasting durum wheat genotypes (Triticum durum Desf.) were used in the present study: Barakatli 95 (tolerant genotype) and Garagylchyg 2 (stress-sensitive genotype). The activity of antioxidant enzymes, ascorbate peroxidase (APO), catalase (CAT), guaiacolperoxidase (GPO), and benzidine peroxidase (BPO), were studied spectrophotometrically. The membrane thermostability was determined by the release of electrolytes from intact plant tissue. Results. It was revealed that guaiacolperoxidase plays a key role in the elimination of reactive oxygen species when exposed to high temperatures, since a significant increase in the activity of this enzyme was observed during short-term thermal stress. Heat stress caused a slight decrease in catalase activity and a significant decrease in the activity of ascorbate peroxidase and benzidine peroxidase. An increase in total protein concentration was observed under heat stress. The indicators of the electrolyte leakage from leaf tissues confirm the variety-specific thermostability of wheat membranes. The membrane damage rate (MDR) increased in direct proportion to the heating temperature and showed the highest value in the sensitive Garagylchyg 2 variety. According to the electrolyte leackage parameters from leaf tissues during hyperthermia, was concluded variety-specific thermal stability of wheat plant membranes.