ABSTRACT
This chapter focuses on the relationship between antioxidant enzymes and their role in response to stress. Antioxidant enzymes can be divided into eight groups, including catalase, peroxidase, superoxide dismutase, glutathione peroxidase, glutathione reductase, monodehydroascorbate reductase, glutathione transferase, and ascorbate peroxidase. Requirements for antioxidant accumulation can vary depending on the type of tolerance. Physiological and genetic evidence suggest that increase in antioxidant defense systems’ capacity in plants exposed to oxidative stress is an important defense mechanism so that there is a very close relationship between increasing antioxidant defense systems activity and reducing oxidative damage. Catalase is responsible for the detoxification of increased levels of H2O2 in peroxisomes, and it is assumed that its activity is necessary to maintain the balance of the redox during oxidative stress. Carotenoids are plant pigments and play an important role in protecting photosynthesis components against oxidative damage. Polyamines are group of phytohormone-like aliphatic amine natural compounds with aliphatic nitrogen structure.
