Postharvest dipping treatment with BABA induced resistance against rot caused by Gilbertella persicaria in red pitaya fruit

β-Aminobutyric acid (BABA) is an elicitor that is capable of inducing disease resistance in many plants. The effect of postharvest BABA treatment on rot caused by Gilbertella persicaria and the underlying mechanisms of action of BABA in pitaya fruit (Hylocereus undatus cv. Zihonglong) were investigated. Fruits were dipped in 10 mM BABA for 15 min and then stored at ambient temperature (25 ± 2 °C, RH 70˜75%). The results showed that 10 mM BABA had no obvious inhibitory effects on G. persicaria in vitro. However, BABA significantly reduced lesion diameter in pitaya inoculated with G. persicaria relative to the control. Furthermore, BABA increased the activities of phenylalanine ammonia lyase (PAL), 4-coumarate/coenzyme A ligase (4CL), peroxidase (POD) and polyphenol oxidase (PPO) and promoted the accumulation of lignin, flavonoids and phenolic compounds in the fruit. These results suggested that postharvest application of BABA via immersion induced resistance in pitaya fruit by activating defense-related enzymes, and BABA treatment may be an alternative method for the control of postharvest diseases in fruits.