Regulation and mechanism of ethylene treatment on storage quality of fresh-cut lotus (Nelumbo nucifera Gaertn.) root slices

This study investigated the effects of 1 g L−1 ethylene immersion treatment for 1 min on the storage quality, antioxidant capacity and ethylene signal transduction pathway of fresh-cut lotus roots. Phenylalanine ammonia-lyase and polyphenol oxidase activities were increased in ethylene treatment slices, and total phenolic content was increased. The activities of peroxidase, catalase and superoxide dismutase were increased after ethylene treatment, as well as the expression of related genes (NnPOD, NnSOD, NnCAT) was upregulated. The rate of superoxide anion radical and hydroxyl radical production in ethylene treatment fresh-cut lotus roots was inhibited, the hydrogen peroxide content was reduced, and the degree of membrane lipid peroxidation was decreased, which delayed browning during the early storage. However, ethylene treatment inhibited microbial growth and improved 1,1-Diphenyl-2-picrylhydrazyl scavenging capacity only during the early storage, promoted respiration and accelerated the decline of hardness and soluble solids content throughout the storage period. At the molecular level, ethylene treatment overall upregulated the transcription of NnmetK, NnACO, NnETR, NnEIN3, and NnERF genes and promoted ethylene biosynthesis and signal transduction. This finding may be related to the senescence of fresh-cut lotus roots during late storage. These results suggest that ethylene treatment improved the antioxidant system, reduced the accumulation of reactive oxygen species, and effectively delayed the early browning of fresh-cut lotus roots, while promoting late senescence.