LAUSR

BACKGROUND Lotus roots (Nelumbo nucifera Gaertn.) are rich in nutrients and have a high ornamental and food value. However, browning had caused huge economical losses and security risks during storage and harvest of fresh-cut lotus. Considering as a vital bioactive molecule, melatonin participated in regulation of various physiological reactions. Our study tried to investigate the role of melatonin on inhibiting lotus browning, and unveil its molecular mechanism. RESULTS Our study illustrated that melatonin application effectively retarded the process of lotus browning, enhanced ROS scavenging-enzymes activities, and alleviated activities of polyphenol oxidase (PPO) and peroxidase (POD). Moreover, melatonin attenuated flavonoid contents, and decreased enzymatic activities in flavonoid biosynthesis. RNA-seq was used to screen the genes regulated by exogenous melatonin in defending against fresh-cut lotus browning. The gene co-expression analysis (GCN) indicated that the transcription factors of MYB5, MYB6 and MYB308 activated by melatonin was negatively related with the expression of PPO and the genes related with flavonoid and phenylpropanoid biosynthesis. These MYBs were positively related with the genes expression of glutathione metabolism. CONCLUSION Melatonin displayed a role of retarding lotus browning by transcriptional suppression of key genes associated with flavonoid and phenylpropanoid biosynthesis through stimulation of MYB5, MYB6 and MYB308. This article is protected by copyright. All rights reserved.