Ethylene-induced postharvest ‘Guifei’ mango peel coloration: Activation of the MiPAL1 promoter by MiERF5 and the MiERF5-MiMYB7 complex

Abstract

Peel coloration strongly influences their sensory quality and commercial value. While ethylene (ETH) promotes and 1-methylcyclopropene (1-MCP) inhibits mango peel coloration, the underlying molecular mechanisms remain incompletely understood. This study investigated the effects of ETH and 1-MCP on ‘Guifei’ mango, focusing on the regulation of the MiPAL1 promoter by MiERF5 and MiMYB7. ETH enhanced the activities of anthocyanin biosynthesis enzymes (PAL, CHI, ANS, DFR, UFGT) and anthocyanin accumulation, whereas 1-MCP suppressed these processes. ETH upregulated MiPAL1 and MiERF5, while 1-MCP increased MiMYB7 expression. Nuclear-localized MiERF5 directly bound and activated the MiPAL1 promoter (verified by Y1H and DLR assays), whereas MiMYB7 repressed it. Crucially, Y2H, BiFC, and LCI assays revealed that a MiERF5-MiMYB7 protein complex binds to MiPAL1, alleviating MiMYB7-mediated repression. Functional validation in mango discs demonstrated that MiMYB7 overexpression inhibited coloration by downregulating MiPAL1, whereas MiERF5 overexpression or co-expression of MiERF5 + MiMYB7 activated MiPAL1 and anthocyanin synthesis. These findings demonstrate that MiERF5 and the MiERF5-MiMYB7 complex positively regulate anthocyanin biosynthesis, revealing a novel regulatory switch for ethylene-mediated peel coloration and potential targets for improving postharvest fruit quality.