Exogenous phytosulfokine α (PSKα) alleviates chilling injury of banana by modulating metabolisms of nitric oxide, polyamine, proline, and γ-aminobutyric acid

Chilling injury reduces the quality and commercial value of banana. The effects of exogenous phytosulfokine α (PSKα) on chilling tolerance of banana via modulating the metabolism of polyamine, proline, γ-aminobutyric acid (GABA) were studied. The results showed that the chilling injury of banana was inhibited by 150 nM PSKα treatment, which was 13.6 % lower than that of the control group at the end of storage. The activities of nitric oxide synthase (NOS), arginine decarboxylase (ADC), ornithine decarboxylase (ODC), and the endogenous NO content were increased significantly by PSKα treatment. The diamine oxidase (DAO) and polyamine oxidase (PAO) activities were inhibited, leading to putrescine (Put), spermine (Spm), and spermidine (Spd) increased. Proline and GABA contents in PSKα-treated banana were also increased, which might be due to the activated biosynthesis pathway and suppressed catabolism pathway. These results demonstrated that exogenous PSKα might be maintain quality and retard chilling injury of banana.