Effect of combined hypobaric and cold storage on defense-related enzymes in postharvest peach fruit during ripening

Peach (Prunus persica) fruit rapidly loses its quality and is highly perishable at ambient temperature after harvest, and postharvest hypobaric treatment (HT) is a potential new technique to delay senescence. We aimed to investigate the postharvest physiology of peach fruit stored under 55 +/- 5 kPa and 4 +/- 0.5 degrees C for 16 days. Biochemical analysis of peach showed that HT maintained higher firmness and lower MDA content, and significantly increased respiration rate compared to CK, but postponed respiration peak. SOD and PPO enzymes were increased remarkably (p < 0.05) on enzyme and gene level. HT obviously inhibited CAT activity and had no significant (p < 0.05) effect on PAL and APX activity. Studies of defense-related genes are required to further explore the induced resistance mechanisms of hypobaric treatments. The results suggested that HT did not stimulate all common enzymatic activities as the previous study stated, SOD and PPO played a vital important role in peach cell defense under the hypobaric condition in this research.