GABA application improves the mitochondrial antioxidant system and reduces peel browning in 'Nanguo' pears after removal from cold storage

Although refrigeration is commonly used in the storage of 'Nanguo' pears (Pyrus ussuriensis Maxim.), long-term refrigeration can result in browning of the pericarp. In this study, we aimed to determine how.-aminobutyrate (GABA) affects the mitochondrial oxidation defense system in 'Nanguo' pears and how it might be used to prevent post-refrigeration peel browning. We found that fruit treated with GABA browned slower, and had lower browning indices and reactive oxygen and malondialdehyde content; increased peroxidase, superoxide dismutase, alternating oxidase, and catalase enzyme activities; and heightened enzyme-related gene expression. The mitochondria of GABA-treated fruit also showed less damage following cold storage, and there were decreases in mitochondrial membrane permeability transition pore concentrations. Furthermore, we detected an increase in the endogenous GABA content of fruits following GABA treatment. These observations indicate that, by regulating the mitochondrial oxidative defense system and maintaining mitochondrial structure, GABA is effective in terms of reducing peel browning.