AUTHOR=Ke Yanguo , Abbas Farhat , Zhou Yiwei , Yu Rangcai , Fan Yanping 

TITLE=Auxin-Responsive R2R3-MYB Transcription Factors HcMYB1 and HcMYB2 Activate Volatile Biosynthesis in Hedychium coronarium Flowers

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.710826

DOI=10.3389/fpls.2021.710826

ISSN=1664-462X

ABSTRACT=<p>Auxin, an important plant hormone, induces the biosynthesis of various secondary metabolites by modulating the expression of auxin-responsive genes. In the ornamental plant <italic>Hedychium coronarium</italic>, linalool and methyl benzoate are biosynthesized by the terpene synthase (TPS) HcTPS5 and the benzoic/salicylic acid methyltransferase (BSMT) HcBSMT2, respectively. However, the transcriptional regulation of this process remains unclear. Here, we identified and functionally characterized the R2R3-MYB transcription factors HcMYB1 and HcMYB2 in regulating the biosynthesis of these floral aroma compounds. <italic>HcMYB1</italic> and <italic>HcMYB2</italic> are specifically expressed in flowers, their expression is correlated with the emission of volatile compounds in flowers, and is induced by auxin. Moreover, HcMYB1 and HcMYB2 interact with the <italic>HcBSMT2</italic> promoter region. HcMYB2 activates the expression of the linalool synthase gene <italic>HcTPS5</italic>. In flowers with <italic>HcMYB1</italic> or <italic>HcMYB2</italic> silenced, the levels of floral scent compounds were significantly reduced, and <italic>HcBSMT2</italic> and <italic>HcTPS5</italic> were downregulated compared with the wild type. Moreover, HcMYB1 form protein-protein interaction with key scent-related HcIAA4 protein to regulate floral aroma production. Taken together, these results indicate that HcMYB1 and HcMYB2 play crucial roles in regulating the formation of scent compounds in <italic>Hedychium coronarium (H. coronarium)</italic> flowers in response to auxin signaling.</p>