PhERF6, interacting with EOBI, negatively regulates fragrance biosynthesis in petunia flowers

Summary In petunia, the production of volatile benzenoids/phenylpropanoids determines floral aroma, highly regulated by development, rhythm and ethylene. Previous studies identified several R2R3‐type MYB trans‐factors as positive regulators of scent biosynthesis in petunia flowers. Ethylene response factors ( ERF s) have been shown to take part in the signal transduction of hormones, and regulation of metabolism and development processes in various plant species. Using virus‐induced gene silencing technology, a negative regulator of volatile benzenoid biosynthesis, Ph ERF 6, was identified by a screen for regulators of the expression of genes related to scent production. Ph ERF 6 expression was temporally and spatially connected with scent production and was upregulated by exogenous ethylene. Up‐/downregulation of the mRNA level of Ph ERF 6 affected the expression of ODO 1 and several floral scent‐related genes. Ph ERF 6 silencing led to a significant increase in the concentrations of volatiles emitted by flowers. Yeast two‐hybrid, bimolecular fluorescence complementation and co‐immunoprecipitation assays indicated that Ph ERF 6 interacted with the N‐terminus of EOBI , which includes two DNA binding domains. Our results show that Ph ERF 6 negatively regulates volatile production in petunia flowers by competing for the binding of the c‐myb domains of the EOBI protein with the promoters of genes related to floral scent.