L-Glutamate treatment alleviates chilling injury of prune (Prunus domestica L.) fruit by regulating ROS homeostasis, GABA shunt, and energy metabolism.

The impacts of L-glutamate (L-Glu) treatment on chilling injury (CI), Ca signaling, mitochondrial ultrastructure, and metabolisms of reactive oxygen species (ROS), γ-aminobutyric acid (GABA), energy of prune fruit under chilling stress were studied. The results found that the optimal concentration of L-Glu to suppress CI occurrence and maintain quality in prune fruit was 0.1 g L, which also enhanced the PdGLRs expression, cytoplasmic Ca concentration, the contents of CaM, and CML under cold stress. Moreover, L-Glu treatment could reduce ROS accumulation and increase GABA content, and energy level, contributing to maintaining the integrity of the mitochondrial structure in cold-stored prune fruit. More importantly, PdGLRs expression and CaM/CML content positively correlated with antioxidant enzyme activities, GABA shunt, and energy status in prune fruit. These results indicated that the enhanced cold resistance of L-Glu-treated prunes might be attributed to the activated Ca signaling, thus improving the antioxidant capacity, GABA, and energy levels.