Changes In Antioxidant Systems And Sucrose Metabolism In Maize Varieties Exposed To Cd

Abstract While it is generally accepted that different maize varieties respond in various ways to cadmium (Cd) stress, the physiological mechanisms that determine how they respond are not well-defined. We do know, however, that antioxidant systems and sucrose metabolism help plants to cope with abiotic stresses, including stress from Cd. Seed is sensitive to Cd stress during germination stage. In this study, we investigated how the antioxidant systems, sucrose metabolism, abscisic acid (ABA) and gibberellin (GA3) concentration in two maize varieties with low (FY9) or high (SY33) sensitivities to Cd changed when Cd was added at 20 mg L−1 over different germination stages (3, 6, and 9 days). As Cd accumulated, the germination rate decreased, and growth was inhibited. The O2•-, malondialdehyde (MDA), and proline (Pro) concentrations, and the superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and lipoxygenase (LOX) activities increased compared to the CK (without Cd). The expression levels of three genes (ZmOPR2, ZmOPR5 and ZmPP2C6) that respond to oxidative stress increased differently in two varieties under Cd stress. The activity of the antioxidant system including the transcript levels of oxidative stress response genes were higher in Cd-tolerant variety, FY9, than in sensitive variety, SY33. And then, we also examined sucrose metabolism levels that were increased compared to the CK. However, it was more active in the Cd-sensitive variety, SY33. Therefore, these results also suggest that antioxidant systems are first respond to Cd stress in maize plants, and sucrose metabolism is cooperation and complement that are exposed to Cd.