Fumigation of SO2 in combination with elevated CO2 regulate sugar and energy metabolism in postharvest strawberry fruit

Elevated CO2 storage causes overconsumption of reducing sugar and lower energy level in postharvest strawberry fruit, reducing the acceptance of this fruit. In order to develop an approach to improve the impaired quality, we applied additional fumigation of SO2 in combination with elevated CO2 storage to postharvest strawberry fruit in the present study. Results exhibited that SO2 fumigation increased contents of sucrose, glucose, fructose, and adenosine triphosphate (ATP) by 11%, 16%, 19%, and 11% respectively on day 8 as well as energy charge. Meanwhile, the content of alcohol and aldehyde decreased. Furthermore, enzyme activities and transcriptional profiles analysis showed inhibition in glycolysis and alcohol fermentation while the tricarboxylic acid (TCA) cycle and electron transfer chain (ETC) were activated by 19-80%. These results indicated that SO2 fumigation maintained sugar contents by inhibiting glycolysis and rerouted the direction of pyruvate by activating aerobic respiration and restricting anaerobic. In addition, the activation of aerobic respiration improved the energy level of postharvest strawberry fruit.