Copper stress-induced changes in biomass accumulation, antioxidant activity and flavonoid contents in Belamcanda chinensis calli

Abstract

Here, the effects of copper stress (CS) on biomass accumulation, physiological parameters of oxidative stress and flavonoid production were investigated in Belamcanda chinensis calli. They were subjected to copper chloride treatments, and the corresponding responses were continuously monitored. Both concentration- and time-dependent physiological changes were uncovered using a multi-index evaluation. The changes in superoxide dismutase (SOD) and guaiacol peroxidase (GPX) activities could be divided into rising and descending stages, with the strongest activities occurring on d 28 and 35, respectively. Similar changes were observed in total flavonoid production, but the maximum yields occurred on different days at different copper chloride concentrations. During the experiment, the level of proline, which functioned in the early stage, declined and was replaced by other protective mechanisms, such as those provided by SOD and GPX, in the late stage. The SOD activity increased along with the copper concentration. However, the GPX activity decreased as the copper concentration increased. Proline’s trend was similar to that of GPX in the early stage but resembled that of SOD in the late stage. Notably, the contents and numbers of flavonoids increased as the copper concentration increased. When the concentration was 200 mg L−1, 11 kinds of flavonoids were generated at the milligram level, which indicates that this approach is potentially valuable for producing biologically active flavonoids. Finally, using a comprehensive analysis of the measured parameters, we concluded that plant cells resisted copper stress by activating multiple antioxidative defense mechanisms in a specific order and complementary manner. Belamcanda chinensis has a remarkable ability to resist copper stress using enzymatic and non-enzymatic defenses, which are activated in a specific order and complementary manner.