Exogenous azacytidine alleviates peel browning of postharvest bananas (Musa acuminata) showing an important role of DNA methylation

Abstract

Banana fruit is usually harvested unripe and the peel browning is a quality challenge during the post-ripening or senescence with or without exogenous ethylene’s ripening acceleration. Browning can occur during logistics, sales, or domestic storage and largely reduces the economic value and consumer liking. 5-azacytidine (5-azaC) is a DNA methylation inhibitor, which has been recently found important in regulating fruit ripening and quality shaping, but its role remains unknown considering banana browning. Currently, we put bananas in the 10 mmol/L solution of 5-azaC for vacuum infiltration (15 min) and then continuous immersion (30 min), and stored them under controlled-release ethylene for 9 days. This treatment effectively retard peel browning. In the final sampling, there were 9.3 times as many bananas in the control group with severe 20–40% browning as there were in the 5-azaC-treated group. Further analysis demonstrated that the polyphenol oxidase (PPO) activity and programmed cell death (PCD) process were inhibited by 5-azaC with its methylation-inhibiting effects, which also somehow modulated the ethylene sensitivity of peel cells to alleviate senescence-related browning. This study is expected to offer valuable insights into banana anti-browning strategy development.