Increasing nicotinamide adenine dinucleotide phosphate hydrogen levels via pentose phosphate pathway promotes phyenylpropanoid metabolism of fresh-cut white mushroom (Agaricus bisporus) under high O2/CO2 storage

Abstract

Cutting usually shortens white mushroom shelf life due to wounding stress. The metabolic activities including phenylpropanoid metabolism can promote wound-healing ability in white mushroom, thus alleviating the negative effect of its cutting process. However, few reports have reported on the relationship between phenylpropanoid metabolism and nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) content. In this study, the effects of high O2/CO2 treatment on the phenylpropanoid metabolism and NADPH level produced via the pentose phosphate pathway (PPP) in white mushroom slices were analyzed. White mushroom slices were first treated with 80% O2+20% CO2 controlled atmosphere for 3 h. The results showed that high O2/CO2 treatment enhanced phenylpropanoid metabolism, which is demonstrated by higher total phenol, flavonoid, and lignin content. High O2/CO2 treatment also reduced the total respiratory rate. However, it increased PPP and tricarboxylic acid cycle rates; inhibited decline in ATP content and improved NAD+ kinase activity. Moreover, NAD+ and NADH contents decreased, whereas NADP+ and NADPH contents increased. To further investigate the relationship between respiratory metabolism and phenylpropanoid metabolism, whole white mushroom were immersed in 0.1 mol L−1 Na3PO4 (a PPP inhibitor) and then the slices were treated with 80% O2+20% CO2 for 3 h. This led to lower key enzyme activity and metabolic product content in the phenylpropanoid metabolism compared with no Na3PO4 treatment. These results demonstrated that high oxygen treatment can effectively induce phenylpropanoid metabolism by increasing NADPH levels via stimulating the PPP. In conclusion, the PPP might play an important role of phenylpropanoid metabolism in fresh-cut white mushroom.