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

Abstract

Anthocyanins and proanthocyanidins (PAs) are important flavonoids in Chinese bayberry (Morella rubra), 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 MrMYB6 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 MrLAR and MrANR during the late ripening stages of bayberries. In addition, overexpression of MrMYB6 in tobacco inhibited the transcript levels of NtCHI, NtLAR, and NtANR2, 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 MrLAR and MrANR and the anthocyanin-specific gene MrANS and MrUFGT. Taken together, our results suggested that MrMYB6 might negatively regulate anthocyanin and PA accumulation in Chinese bayberry.

Comparative Transcriptome Analysis Uncovers the Regulatory Roles of MicroRNAs Involved in Petal Color Change of Pink-Flowered Strawberry

“…Previous studies indicated that AtMYB114 , PyMYB114 , and MdMYB114 were active regulators of anthocyanin biosynthesis in Arabidopsis ( Gonzalez et al, 2008 ), pear ( Yao et al, 2017 ), and apple ( Jiang et al, 2021 ). Other studies suggested that MdMYB12 and MrMYB6 negatively regulate anthocyanin accumulation in apple ( Mao et al, 2021 ) and Chinese bayberry ( Shi et al, 2021 ). Here, our degradome analysis showed that FamiRNA828a and FamiRNA858_R-2 targeted FaMYB114 and FaMYB308 , respectively.…”

Tartary Buckwheat R2R3-MYB Gene FtMYB3 Negatively Regulates Anthocyanin and Proanthocyanin Biosynthesis

“…Similarly, other SG4-like also have an inhibitory effect on anthocyanin and PA bio-synthesis. For example, MrMYB6 might negatively regulate anthocyanin and PA ac-cumulation in Chinese bayberry [ 41 ]. A similar finding was observed when PtrMYB57 was overexpressed in poplar [ 42 ].…”

A comparative metabolomics study of anthocyanins and taste components in Chinese bayberry (Morella rubra) with different flesh colors

“…Thirteen of these were significantly down-regulated and differentially accumulated in BDK ( Table 1 ). Proanthocyanidins usually have astringent tastes ( Shi et al, 2021 ), and differences in the types and contents of these compounds will thus affect the fruit flavor. We found that the contents of procyanidin A2 and procyanidin C1 in BDK were lower than in DK.…”

“…Flavonoid secondary metabolites contribute to both the development and quality of plants ( Winkel-Shirley, 2001 ), with anthocyanins and proanthocyanidins forming the major flavonoid classes present in fruit ( Saito et al, 2013 ; Sakaguchi et al, 2008 ). Anthocyanins contribute to fruit color, including orange, red, pink, or blue colors, while proanthocyanidins are responsible for flavor and astringency ( Shi et al, 2021 ). Both classes represent good sources of natural antioxidants that have a role in reducing cardiovascular disease and assist with the treatment of diabetes ( Bao et al, 2005 ; Middleton, Kandaswami & Theoharides, 2000 ; Shi et al, 2018a ; Sun et al, 2012a ; Sun et al, 2012b ; Zhang et al, 2015 ).…”