Exogenous dopamine ameliorates chilling injury of banana fruits during cold storage

This study investigated postharvest dopamine treatment efficiency in ameliorating chilling injury of banana fruits during storage at 7 ºC for 21 days. Our results showed that dopamine treatment at 150 µM promoted phenols and flavonoids biosynthesis acquired by higher phenylalanine ammonia-lyase (PAL) expression and activity concurrent with lower polyphenol oxidase (PPO) expression and activity leading to higher DPPH, FRAP, and ABTS radicals scavenging activity. In addition, dopamine treatment at 150 µM promoted endogenous proline biosynthesis by activating pyrroline-5-carboxylate synthetase (P5CS) and ornithine δ-aminotransferase (OAT) expression and activity concurrent with suppressing proline dehydrogenase (ProDH) expression and activity. Furthermore, higher endogenous γ-aminobutyric acid (GABA) biosynthesis in banana fruits by 150 µM dopamine treatment was accompanied by higher glutamate decarboxylase (GAD) and GABA transaminase (GABA-T) expression and activity. Therefore, our results suggest that dopamine treatment at 150 µM might be employed for banana fruits chilling injury amelioration by enhancing phenylpropanoid pathway activity and boosting endogenous proline and GABA biosynthesis.