AUTHOR=Shi Liyu , Chen Xin , Wang Kang , Yang Minjie , Chen Wei , Yang Zhenfeng , Cao Shifeng 

TITLE=MrMYB6 From Chinese Bayberry (Myrica rubra) Negatively Regulates Anthocyanin and Proanthocyanidin Accumulation

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.685654

DOI=10.3389/fpls.2021.685654

ISSN=1664-462X

ABSTRACT=<p>Anthocyanins and proanthocyanidins (PAs) are important flavonoids in Chinese bayberry (<italic>Morella rubra</italic>), which functions in fruit color and exhibits multiple health promoting and disease-preventing effects. To investigate the regulation of their biosynthesis in Chinese bayberries, we isolated and identified a subgroup 4 MYB transcription factor (TF), MrMYB6, and found MrMYB6 shared similar repressor domains with other MYB co-repressors of anthocyanin and PA biosynthesis after sequence analysis. Gene expression results revealed the transcripts of <italic>MrMYB6</italic> were negatively correlated with the anthocyanin and insoluble PA contents and also with the gene expressions involved in anthocyanin biosynthesis and PA specific genes such as <italic>MrLAR</italic> and <italic>MrANR</italic> during the late ripening stages of bayberries. In addition, overexpression of <italic>MrMYB6</italic> in tobacco inhibited the transcript levels of <italic>NtCHI, NtLAR</italic>, and <italic>NtANR2</italic>, resulting into a decline in the levels of anthocyanins and PAs in tobacco flowers. We further found that MrMYB6 interacted with MrbHLH1 and MrWD40-1 to form functional complexes that acted to directly repress the promoter activities of the PA-specific gene <italic>MrLAR</italic> and <italic>MrANR</italic> and the anthocyanin-specific gene <italic>MrANS</italic> and <italic>MrUFGT</italic>. Taken together, our results suggested that MrMYB6 might negatively regulate anthocyanin and PA accumulation in Chinese bayberry.</p>