Changes in polyamine oxidase enzyme activity and antioxidant system function in two tolerant and susceptible maize cultivars under drought stress

Drought stress is one of the most important environmental stresses that disrupt metabolism, decrease the growth and yield of plants. The response of maize (Zea mays L.) to drought stress highly depends on genotype and plant growth stage. In this study, the activity of polyamine oxidase (PAO) and antioxidant enzymes, as well as H2O2 content in susceptible (260) and resistant (Karoon) cultivars in response to drought stress, were evaluated in maize seedlings. For this purpose, 10-day-old seedlings were exposed to drought stress via withholding water for 7 days. Our results showed that under drought stress, H2O2 content differs between two cultivars, where the significant increase in H2O2 level was observed in roots of tolerant and shoots of sensitive genotype. In general, drought stress resulted in an increase in the activity of Polyamine oxidase (POA), the function of PAO at pH 8 and pH 6.5 is slightly different between cultivars. The higher activity of PAO at pH 8 in root and shoot of Karoon genotype under drought could be considered as a result of the activity of peroxisomal PAOs. Furthermore, the activity of antioxidant enzymes including superoxide dismutase, peroxidase, and catalase increases under drought stress. In the Karoon cultivar, increase in superoxide dismutase activity was observed in root and shoot, where the rise in peroxidase was only recorded at shoots. The activity of catalase enzyme showed a reduction in shoots of tolerant Karoon. Our results demonstrated that superoxide dismutase and peroxisomal PAO are two key enzymes that can play a role in regulating and homeostasis of H2O2 in tolerant cultivars.

کلیدواژه ها:

Polyamine oxidase ، Antioxidant enzymes ، Drought ، Maize ، H2O