Exogenous phytosulfokine α (PSKα) applying delays senescence and relief decay in strawberry fruits during cold storage by sufficient intracellular ATP and NADPH availability

Abstract Herein, we employed exogenous phytosulfokine α (PSKα) for delaying senescence and lessening decay in strawberry fruits during storage at 4 °C for 18 days. Our results showed that the strawberry fruits treated with 150 nM PSKα exhibited lower expression of poly-ADP-ribose polymerase 1 (PARP1) gene, leading to a higher intracellular NAD+ availability, beneficial for a sufficient provision of intracellular NADP+ with the activity of NAD kinase (NADK). Moreover, higher activities of glucose 6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH), and methylenetetrahydrofolate dehydrogenase (MTHFD) may be the reason for the sufficient intracellular availability of NADPH in strawberry fruits treated with 150 nM PSKα. In addition, strawberry fruits treated with 150 nM PSKα exhibited a sufficient availability of ATP resulted from higher activities of succinate dehydrogenase (SDH) and cytochrome c oxidase (CCO). Therefore, our results indicate that exogenous PSKα could be beneficial for delaying senescence and reducing decay in strawberry fruits during cold storage.