Low-temperature conditioning combined with cold storage inducing rapid sweetening of sweetpotato tuberous roots (Ipomoea batatas (L.) Lam) while inhibiting chilling injury

Sweetpotato tuberous roots (Ipomoea batatas (L.) Lam) are prone to chilling injury (CI) when stored at low temperature. Here, tuberous roots were subjected to low-temperature conditioning (LTC) at 10 °C for 5 d before exposure to chilling stress under cold storage at 4 °C for 28 d. After investigation of antioxidant and sugar metabolic responses to chilling stress, the results indicated that LTC treatment can enhance sweetness while effectively reducing CI observed in roots stored at 4 °C for 28 d. Moreover, LTC triggered increased sucrose levels, transcription of enzyme genes, and increased superoxide dismutase, catalase, and ascorbate peroxidase activities, while preventing increases in malondialdehyde content, relative leakage, and production of reactive oxygen species during cold storage. Furthermore, LTC may trigger beta-amylase gene transcription via C-repeat binding factor (CBF) pathway induction. Therefore, LTC combined with cold storage can induce fast sweetening in tuberous roots while preventing chilling injury.