Roles of ROS metabolism and phenylpropanoid pathway in quality maintenance of postharvest Pleurotus eryngii under hyperoxia stress

Hyperoxia application has been proven to be effective in mushrooms preservation, however, the possible induction mechanisms of hyperoxia stress on P. eryngii quality maintenance are incompletely understood. In this study, Pleurotus eryngii treated with hyperoxia (80% O2 +20% N2) and the induced resistance responses of fruiting bodies were mainly investigated through ROS metabolism and phenylpropanoid pathway. The application of hyperoxia could significantly alleviate the quality deterioration of P. eryngii during storage, as observed by higher maintenance of firmness, nutrient substance and membrane integrity. Moreover, hyperoxia application induced the production of hydrogen peroxide (H2O2) in the early stage, as well as the enzymatic antioxidant defense system. The NADPH oxidase genes (PeNoxR) and MAPK signaling pathway were also up-regulated during hyperoxia stress. Besides, hyperoxia stress also promoted the accumulation of major secondary metabolites and up-regulated the transcription levels of the key genes involved in phenylpropanoid pathway. Taken together, this study provided substantial evidences that hyperoxia could induce stress resistance in P. eryngii due to its positive regulation of ROS metabolism-modifying enzyme activities and genes, as well as possible activated phenylpropanoid pathway, therefore delaying the quality deterioration of P. eryngii during postharvest period.