Petunia ChIP-Seq in corolla development

Volatile organic compounds (VOCs) produced in the flower impart scent characteristics to attract pollinators and promote reproductive success. VOC production and release are tightly spatiotemporally controlled. In petunia, VOCs are produced in the corolla tissue post-anthesis, predominantly using phenylalanine as a precursor. VOC biosynthesis features a complex network of enzymes involved in primary and secondary metabolism, interlinked with alternative phenylpropanoid branches which share common metabolic precursors. In this study, we uncovered dynamic H3K9ac histone modification genome-wide and transcriptome reprogramming in the corolla tissue post-anthesis, enriched at gene loci that underlie the activation of phenylalanine and VOC biosynthesis. We observed a concurrent transcriptional repression and a lack of H3K9ac modification among genes involved in other phenylpropanoid pathways that compete for shared metabolic precursors with VOC biosynthesis. This study demonstrated that a chromatin-level regulatory mechanism co-activates primary and secondary metabolic pathways, in tandem with shutdown of competing metabolic pathways, to facilitate VOC synthesis in petunia.