Glycine Enhances Oxidative Stress Tolerance and Biocontrol Efficacy of Sporidiobolus pararoseus against Aspergillus niger Decay of Apples

Apples are deeply loved by people because of their rich nutritional value, but they are susceptible to rotting. The use of antagonistic yeast is a promising method for controlling postharvest fruit diseases, but biocontrol efficacy of yeast will be weakened in environmental stress. In this study, the effects of glycine (Gly) on the oxidative stress tolerance and the biocontrol efficacy of Sporidiobolus pararoseus (S. pararoseus) against Aspergillus niger (A. niger) are discussed. Under the stimulation of H(2)O(2), the yeast cells treated with Gly (1 mM) showed lower ROS content, less mitochondrial impairment and cellular oxidative damage, and the cell survival rate was significantly higher than Gly-untreated yeast. The yeast cells exposed to Gly significantly increased the activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and the content of glutathione (GSH). Notably, Gly-treated yeast cells had better biocontrol efficacy against A. niger in postharvest apples. The lesion diameter and decay incidence were reduced by 17.67 mm and 79.63% compared to the control, respectively, when S. pararoseus was treated with 1 mM Gly. Moreover, Gly-treated yeast increased the antioxidant enzymes activities and their gene expression were up-regulated in apples. These results indicated that 1 mM Gly not only reduced the oxidative damage of yeast, but also induced resistance-related enzymes of apples under oxidative stress, which contributed to enhancing the biocontrol efficacy of S. pararoseus against A. niger in apples.