The main factors inducing postharvest lignification in king oyster mushrooms (Pleurotus eryngii): Wounding and ROS-mediated senescence.

This study was the first investigation into the main inducers of two lignifications by examining the changes of physicochemical properties and gene expression in king oyster mushrooms, under different conditions, during 21 days of storage. The results showed that the toughness, firmness and gumminess of the no-wounding treatment decreased to approximately 75-82.5% of the initial values, and the lignin content and expression of Pe4CL1 and Pe4CL3 decreased by 21-40% and 22-77%, respectively, in comparison to those of the other treatments in the first lignification. These findings indicated that wounding was the main factor inducing the first lignification. The second lignification of tested mushrooms was positively correlated with reactive oxygen species (ROS)-mediated senescence, accompanied by increased malondialdehyde (MDA) content, electrolyte leakage rate and mitochondrial dysfunction, which showed that ROS-mediated senescence played an essential role in the second lignification. This study is helpful for effective strategies to reduce lignification in stored mushrooms.