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Chilling injury(CI)is considered to be the main problem in peach fruit refrigeration industry.The development of CI in peach fruit limits refrigeration and cold chain transportation.Glycine betaine(GB),a kind of quaternary ammonium alkaloid,is an important osmotic adjustment substance that plays an important role in maintaining cell osmotic pressure,protecting protein or enzymes function,and regulating stress response in plant.However,little information concerning the effect of exogenous GB on reducing CI and inducing cold tolerance in peach fruit has been available.The results of this study showed that GB treatment significantly prevented CI and maintained low flesh firmness and high extractable juice in peach fruit during cold storage.The accumulation of endogenous GB,γ-aminobutyric acid(GABA)and proline contents in peaches was enhanced by GB treatment resulting from increasing activities of metabolism enzymes,including betaine aldehyde hydrogenase(BADH),glutamate decarboxylase(GAD),△1-pyrroline-5-carboxylate synthetase(P5CS)and ornithine δ-aminotransferase(OAT).Moreover,high level of energy status in GB-treated peach fruit was found.These results indicated that GB treatment enhanced chilling tolerance in peaches due to induction of energy status,endogenous GB,GABA and proline contents,which prevented membrane damage.The accumulation of endogenous GB,GABA and proline contents were enhanced by exogenous GB treatment due to inducing their metabolism related enzymes activities.GB treatment also increased energy content and decreased membrane damage in peach fruit.To our best knowledge,this is the first report that exogenous GB alleviated CI and induced chilling tolerance in peach fruit.However,further studies are needed to explore the gene expression and molecular networks regulated by GB in response to chilling stress.