Histone methylation plays important roles in plant development. However, the role of histone methylation in fruit ripening remains unclear. Here, a total of 16 Jumonji domain-containing proteins (JMJs) were identified from banana genome. During fruit ripening, expression of MaJMJ15 was significantly upregulated. Exogenous ethylene accelerated the upregulation whereas 1-methylcyclopropene delayed the process, suggesting that MaJMJ15 positively regulates banana fruit ripening. MaJMJ15 is an H3K27me3 site-specific demethylase. Transient overexpression of MaJMJ15 promoted banana fruit ripening. Moreover, the global H3K27me3 was decreased by MaJMJ15. Furthermore, MaJMJ15 directly targeted several key ripening-related genes (RRGs) in banana including NAC transcription factor 1/2 (MaNAC1/2), 1-aminocyclopropane-1-carboxylate synthase 1 (MaACS1), 1-aminocyclopropane-1-carboxylate oxidase 1 (MaACO1) and expansin 2 (MaEXP2), removed H3K27me3 from their chromatin, and activated their expression. Our data suggest that MaJMJ15 is an H3K27me3 demethylase, which is involved in the regulation of banana fruit ripening by activating expression of key RRGs via removal of H3K27me3.

组蛋白甲基化在植物发育中起着重要作用。然而，组蛋白甲基化在果实成熟中的作用仍不清楚。在这里，总共从香蕉基因组中鉴定出16 个包含 Jumonji 结构域的蛋白质 ( JMJs )。在果实成熟期间，MaJMJ15的表达显着上调。外源乙烯加速了上调，而 1-甲基环丙烯延迟了该过程，表明 MaJMJ15 正向调节香蕉果实成熟。MaJMJ15 是一种 H3K27me3 位点特异性去甲基化酶。MaJMJ15的瞬时过表达促进香蕉果实成熟。此外，MaJMJ15 减少了全局 H3K27me3。此外，MaJMJ15 直接靶向香蕉中的几个关键成熟相关基因 (RRG)，包括 NAC 转录因子 1/2 ( MaNAC1/2 )、1-氨基环丙烷-1-羧酸合酶 1 ( MaACS1 )、1-氨基环丙烷-1-羧酸氧化酶1 ( MaACO1 ) 和扩展蛋白 2 ( MaEXP2 ) 从它们的染色质中去除 H3K27me3，并激活它们的表达。我们的数据表明 MaJMJ15 是一种 H3K27me3 去甲基化酶，它通过去除 H3K27me3 激活关键 RRG 的表达来参与香蕉果实成熟的调控。