Ellagic acid delays postharvest senescence and browning of Phyllanthus emblica L. fruit by regulating a novel PemiR477-PeAPX2 module and maintaining AsA-GSH redox homeostasis

Phyllanthus emblica L., a medicinal and edible fruit, is valued for its exceptionally high ascorbic acid (AsA) content, but postharvest senescence and rapid pericarp browning severely limit its marketability. In this study, ellagic acid (EA) was applied to harvested emblica fruit to elucidate its effects on postharvest quality deterioration and pericarp browning, as well as the underlying physiological and molecular mechanisms. EA treatment delayed the loss of fruit marketability and the increase in browning index, while reducing cell membrane permeability, lipid peroxidation and reactive oxygen species (ROS) accumulation. Moreover, EA treatment enhanced SOD and CAT activities and restrained the increases in PPO and POD activities. Additionally, higher AsA and GSH contents and AsA/DHA and GSH/GSSG ratios were maintained in EA-treated fruit, together with higher activities and transcript abundance of enzymes involved in the AsA-GSH cycle. Notably, a novel PemiR477-PeAPX2 module was identified, and the targeting relationship between PemiR477 and PeAPX2 was validated in vivo . EA treatment suppressed PemiR477 expression while maintaining higher transcript levels of PeAPX2 during storage, in parallel with enhanced APX activity and a more reduced AsA pool. Collectively, these results suggested that EA treatment effectively delayed postharvest senescence and pericarp browning of emblica fruit by regulating PemiR477-PeAPX2 module and maintaining AsA-GSH redox homeostasis.