Abstract

Deciphering the mechanism of malate accumulation in apple ( Malus domestica Borkh.) fruit is crucial for improving its flavor quality and enhancing its health benefits for humans. In this study, we identified an AP2/ERF family transcription factor, MdERF106, which plays a critical role in regulating malate levels. Functional analyses revealed that overexpression of MdERF106 significantly increased malate content in apple fruits and calli. Concurrently, the expression of the malate transporter gene MdALMT9 was markedly upregulated. Through yeast one-hybrid and electrophoretic mobility shift assays, we further demonstrated that MdERF106 directly binds to the DRE motif within the promoter region of MdALMT9 . Moreover, luciferase reporter assay confirmed that MdERF106 activates the transcriptional activity of the MdALMT9 promoter. Collectively, these results establish that MdERF106 acts as a positive regulator of malate accumulation by directly enhancing the transcription of MdALMT9 . This work provides new insights into the metabolic regulatory network controlling malate accumulation in apple fruit. Graphical