Modulations of the antioxidants defence system in two maize hybrids during flooding stress

Flooding stress nowadays is one of the major stressors for plants under climate change. This kind of stress may cause severe depression of the plant's growth through inhibition of photosynthesis and oxidative cell damage as well as changes in cell respiration. The present work aimed to study the effect of flooding stress on oxidative and antioxidative parameters in leaves of two maize hybrids (ZP 555 and ZP 606). Leaves of maize plants at the stage of three fully developed leaves were harvested after 6, 24, 72, and 144 h of applied flooding stress. Leaves were used for determination of physiological (the content of photosynthetic pigments and soluble proteins), oxidative stress parameters (the content of malondialdehyde (MDA) and H₂O₂) as well as antioxidants (the total polyphenols content, and activity of antioxidative enzymes [catalase (CAT, EC 1.11.1.6), superoxide dismutase (SOD, EC 1.15.1.1), and Class III peroxidases (POX, EC, 1.11.1.7)]). Results indicated that flooding stress-induced time-dependent changes of measured parameters and those hybrids differ in response to stress. The noticeable difference between hybrids was detected in the H₂O₂ and MDA content. An increase in the activity of SOD, POX and polyphenols content, with the most pronounced changes in POX activity and polyphenols concentration, could minimize the cellular damage caused by flooding. The results of the present study suggest that a more robust antioxidative metabolism is essential under flooding stress and could be a protective strategy against oxidative damage induced by flooding in ZP 606 maize plants compared to ZP 555 plants.