Glycine betaine reduces chilling injury in peach fruit by enhancing phenolic and sugar metabolisms

Glycine betaine (GB) treatment is useful to reduce chilling injury (CI) of several kinds of fruits including peach. However, the regulatory mechanism remains unknown. In this study, peach fruit was treated with 10 mmol L-1 GB solution for 10 min. The effects of GB treatment on CI, phenolic and soluble sugar metabolism were investigated in this study. Moreover, phenylpropanoid and soluble sugar content, and enzyme activities associated with phenolic and sugar metabolisms were also measured. The results showed that GB reduced CI and maintained high levels of total phenolic and flavonoid content. The activities of phenylpropanoid metabolism-related enzymes were significantly enhanced by GB. Higher content of sucrose and lower contents of fructose and glucose were observed in GB-treated fruits. Therefore, our results showed that GB could enhance chilling tolerance of peach through regulating phenolic and sugar metabolisms, and maintaining high levels of individual phenolic and sucrose content.