AUTHOR=Zhou Hui , Peng Qian , Zhao Jianbo , Owiti Albert , Ren Fei , Liao Liao , Wang Lu , Deng Xianbao , Jiang Quan , Han Yuepeng 

TITLE=Multiple R2R3-MYB Transcription Factors Involved in the Regulation of Anthocyanin Accumulation in Peach Flower

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01557

DOI=10.3389/fpls.2016.01557

ISSN=1664-462X

ABSTRACT=<p>Anthocyanin accumulation is responsible for flower coloration in peach. Here, we report the identification and functional characterization of eight flavonoid-related R2R3-MYB transcription factors, designated <italic>PpMYB10.2, PpMYB9, PpMYBPA1, Peace, PpMYB17, PpMYB18, PpMYB19</italic>, and <italic>PpMYB20</italic>, respectively, in peach flower transcriptome. <italic>PpMYB10.2</italic> and <italic>PpMYB9</italic> are able to activate transcription of anthocyanin biosynthetic genes, whilst <italic>PpMYBPA1</italic> and <italic>Peace</italic> have a strong activation on the promoters of proanthocyanin (PA) biosynthetic genes. <italic>PpMYB17-20</italic> show a strong repressive effect on transcription of flavonoid pathway genes such as <italic>dihydroflavonol 4-reductase</italic>. These results indicate that anthocyanin accumulation in peach flower is coordinately regulated by a set of R2R3-MYB genes. In addition, <italic>PpMYB9</italic> and <italic>PpMYB10.2</italic> are closely related but separated into two groups, designated MYB9 and MYB10, respectively. <italic>PpMYB9</italic> shows a strong activation on the <italic>PpUGT78A2</italic> promoter, but with no effect on the promoter of <italic>PpUGT78B</italic> (commonly called <italic>PpUFGT</italic> in previous studies). In contrast, <italic>PpMYB10.2</italic> is able to activate the <italic>PpUFGT</italic> promoter, but not for the <italic>PpUGT78A2</italic> promoter. Unlike the <italic>MYB10</italic> gene that is universally present in plants, the <italic>MYB9</italic> gene is lost in most dicot species. Therefore, the <italic>PpMYB9</italic> gene represents a novel group of anthocyanin-related MYB activators, which may have diverged in function from the <italic>MYB10</italic> genes. Our study will aid in understanding the complex mechanism regulating floral pigmentation in peach and functional divergence of the R2R3-MYB gene family in plants.</p>