The Jasmonate-Activated Transcription Factor MdMYC2 Regulates and Ethylene Biosynthetic Genes to Promote Ethylene Biosynthesis during Apple Fruit Ripening.

The plant hormone ethylene is critical for ripening in climacteric fruits, including apple (). Jasmonate (JA) promotes ethylene biosynthesis in apple fruit, but the underlying molecular mechanism is unclear. Here, we found that JA-induced ethylene production in apple fruit is dependent on the expression of , an ACC synthase gene involved in ethylene biosynthesis. The expression of , encoding a transcription factor involved in the JA signaling pathway, was enhanced by MeJA treatment in apple fruits, and MdMYC2 directly bound to the promoters of both and the ACC oxidase gene and enhanced their transcription. Furthermore, MdMYC2 bound to the promoter of , encoding a transcription factor involved in the ethylene-signaling pathway, thereby activating transcription. We also found that MdMYC2 interacted with MdERF2, a suppressor of and This protein interaction prevented MdERF2 from interacting with MdERF3 and from binding to the promoter, leading to increased transcription of Collectively, these results indicate that JA promotes ethylene biosynthesis through the regulation of MdERFs and ethylene biosynthetic genes by MdMYC2.