Transcriptional repression of an ABC transporter gene OfABCG13 by AP2/ERF transcription factor OfERF177 attenuates floral aroma emission in Osmanthus fragrans

Emitted volatile organic compounds (VOCs) are important for attracting pollinators and enemies of herbivores as well as critical ornamental traits of horticulture crops. ATP-binding cassette (ABC) transporters are known to play important roles in the emission of floral VOCs. Osmanthus fragrans is a well-known aromatic woody evergreen species, predominantly produces terpenoid compounds as its primary floral VOCs. However, the fundamental regulatory mechanisms underlying floral VOCs emission in O . fragrans is still unclear. In this study, we identified 168 ABC transporters clustered into eight subfamilies in O . fragrans . Here, OfABCG13, a flower tissue-specific ABCG subfamily member, was localized in the cell membrane and exhibited a high positive correlation between its expression and terpenoid compounds emission levels. Further, both of the transient and stable overexpression transgenic functional analysis showed that OfABCG13 can significantly promote the terpenoid compounds emission levels. In addition, we demonstrated that the nucleus-localized transcription factor OfERF177 can decrease the emission of terpenoid compounds by suppressing the expression of OfABCG13 and OfCCD4 . Our results revealed a novel OfERF177-OfABCG13 transcriptional module that regulates floral aroma by controlling terpenoid compounds emission in O . fragrans , providing a potential strategy for improving the aromatic quality of horticultural crops.