Prohibitin StPHB3 affects the browning of fresh-cut potatoes via influencing antioxidant capacity and polyphenol oxidase activation

Enzymatic browning causes a decline in consumer’s acceptance of fresh-cut products. Previous study showed reactive oxygen species (ROS) is associated with enzymatic browning, and prohibitin (PHB) is involved in ROS formation. However, whether PHB influences the enzymatic browning is still unknown. In this paper, changes of StPHB3 transcript levels after cutting were investigated, then stphb3 mutants were constructed through CRISPR/Cas9 and the browning difference between stphb3 mutants and wild type was compared, finally the mechanism of PHB influencing the browning was explored. The results showed that the transcript levels of StPHB3 were enhanced in potato (cultivar Desiree) tubers after fresh cutting. Mutation of StPHB3 caused lower browning, less production of soluble quinones, decreased malondialdehyde (MDA) content, increased 1,1-Diphenyl-2-picrylhydrazyl (DPPH) inhibition, and increased total phenol contents. Additionally, polyphenol oxidase (PPO) activity and StPOT32 gene transcript level were also reduced after disturbing StPHB3 gene expression. StPHB3 was found to be located within the chloroplast same as the predominant location and activation site of PPO protein. Yeast two-hybrid (Y2H) and Co-Immunoprecipitation (Co-IP) assays showed StPHB3 interacted with PPO. And mature PPO contents were decreased in stphb3. These results suggest that suppression of StPHB3 can alleviate the browning of fresh-cut potatoes by enhancing the antioxidant activity and inhibiting PPO activation.