Ethylene modulates the phenylpropanoid pathway by enhancing expression via the ERF5-melatonin-ERF104 pathway in grape seeds.

The interaction between ethylene and melatonin in the regulation of polyphenol metabolism and the underlying mechanism remain largely unclear. This work demonstrated that ethylene treatment increased melatonin biosynthesis by inducing the expression in grape seeds. Ethylene-induced VvERF5 transactivated via binding to the ethylene response element in its promoter. overexpression led to an increase in melatonin biosynthesis while its suppression generated the opposite results in grape seeds, calli, and/or seeds. A melatonin-responsive element (MTRE) was identified, and melatonin-induced VvERF104 was found to bind to the MTRE of the promoter and activate its expression. overexpression widely modified the expression of genes in the phenylpropanoid pathway and phenolic compound content in grape seeds. DNA affinity purification sequencing revealed that the MEME-1 motif was the most likely binding sites of . , , and were verified to be the target genes of VvMYB14. Additionally, the overexpression of or increased the expression of , , and , as well as the levels of the corresponding metabolites. Moreover, the roles of , , and in mediating ethylene-induced changes in the phenylpropanoid pathway were elucidated using their suppressing seeds. Collectively, ethylene increased the expression via the pathway of ERF5-melatonin-ERF104 and thereby modified the phenylpropanoid pathway.