Transcription factor VviAGL6a regulates fruit ripening by directly activating grape VviJMJ21

•The 2 mmol/L histone methylase inhibitor MTA can promote grape ripening.•The differential gene VviJMJ21 was screened by transcriptome analysis.•The transcriptional regulation prediction network showed that VviAGL6a targeted to regulate VviJMJ21.•Yeast single hybridization and double luciferin experiments demonstrated that VviAGL6a directly activated the expression of VviJMJ21 by directly binding to its promoter. Early ripening of grapes can not only promote the adjustment of grape planting variety structure, but also improve the economic benefits of grape growers. In this study, 'Kyoho' grape berries were dipped with 2 mmol/L of the histone methyltransferase inhibitor, MTA, which was found to promote early ripening of grapes, and then transcriptome analysis was performed to investigate the regulatory mechanisms of MTA treatment on grape berry development and ripening. The transcriptome results showed that VviJMJ21 was induced and up-regulated by MTA treatment, in addition, the transcriptional regulation prediction network indicated that VviAGL6a targeted VviJMJ21. Yeast one-hybrid and Dual luciferase assay demonstrated that VviAGL6a directly activated the expression of VviJMJ21 by directly binding to its promoter. The results of this study will provide theoretical basis and molecular insights for further exploration of the effects of histone methylation on early ripening of grape berries.