MnSOD and 9-LOX gene expression along with antioxidant changes of Capsicum annuum cv. Kulai during postharvest treatment

Abstract

There is increased interest in the consumption of hot pepper (Capsicum annuum cv. Kulai) due to its high antioxidant content; however, pepper is also highly susceptible to postharvest losses. The goal of this study was to evaluate the combined effect of 1-methylcyclopropene (1-MCP) and modified-atmosphere packaging (MAP) compared to MAP alone in maintaining the quality and antioxidant activity of Kulai pepper during low-temperature storage. The enzymatic activities and expression levels of superoxide dismutase (SOD) and lipoxygenase (LOX) were determined to evaluate the changes in their molecular levels in response to the postharvest treatment. The concentrations of total antioxidants as well as hydrogen peroxide (H2O2) and thiobarbituric acid reactive substances (TBARS) were also determined to evaluate the changes in the antioxidant status during storage. The study revealed that a combination treatment (1-MCP and MAP) had a pronounced effect, extending the shelf life of the fruit up to 25days over MAP treatment alone with the retention of high antioxidant content. The combined treatment greatly suppressed the production of H2O2 and TBARS by 29.3% and 57.6% concomitant with an 8-fold increase in SOD activity and a decrease in LOX activity up to 75.4% relative to the control. The total antioxidant level increased consistently throughout the storage period. The overall results indicated that the combination treatment of MAP and 1-MCP provided a sustained protective effect for Kulai peppers stored at low temperature, with the quality of the pepper maintained throughout handling.