Postharvest treatment with glycine betaine enhances chilling tolerance of blood orange fruit by increasing antioxidant defence systems and osmoregulation during cold storage

In this study, postharvest treatment with glycine betaine (GB) was performed in order to reduce chilling injury (CI) of blood orange cv. Moro at 3 degrees C for 90 days. Vacuum infiltration of GB was applied at 15 and 30 mM at 30 kPa for 8 min. Parameters were evaluated after 1, 30, 60, and 90 days of storage plus 2 days at 20 degrees C to simulate shelf life conditions. GB treatment at 30 mM significantly reduced CI in 'Moro' blood orange fruit during the storage period. In addition, electrolyte leakage (EL), malondialdehyde (MDA), and hydrogen peroxide (H2O2) lower content was found in GB-treated fruit. Furthermore, GB treatment enhanced catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL) activities, and proline content, but suppressed polyphenol oxidase (PPO) and peroxidase (POD) activities. Overall, the most effective treatment was 30 mM GB leading to preserving the outer layer of the epidermal cuticle (the cuticle), and epidermal wax approved by scanning electron microscopy (SEM) images. For this reason, it can be concluded that GB treatment may be a promising approach for reducing the CI of 'Moro' blood orange fruit at low temperatures.

Automated summary

This study investigated the effect of postharvest treatment with glycine betaine (GB) on reducing chilling injury (CI) in blood orange cv. Moro during storage at 3 degrees C. Treatment with 30 mM GB significantly reduced CI, as indicated by lower electrolyte leakage, malondialdehyde (MDA), and hydrogen peroxide (H2O2) content compared to the control. Additionally, GB treatment enhanced the activities of catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD), and phenylalanine ammonia-lyase (PAL), and increased proline content, while suppressing polyphenol oxidase (PPO) and peroxidase (POD) activities. Scanning electron microscopy (SEM) images confirmed that 30 mM GB treatment preserved the outer layer of the epidermal cuticle and epidermal wax. These findings suggest that GB treatment may be a promising approach for reducing CI in blood orange fruit at low temperatures.