Shi Liyu, Chen Xin, Wang Kang, Yang Minjie, Chen Wei, Yang Zhenfeng, Cao Shifeng
College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo, China.
Front Plant Sci. 2021 Jun 18;12:685654. doi: 10.3389/fpls.2021.685654. eCollection 2021.
Anthocyanins and proanthocyanidins (PAs) are important flavonoids in Chinese bayberry (), 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 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 and during the late ripening stages of bayberries. In addition, overexpression of in tobacco inhibited the transcript levels of , and , 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 and and the anthocyanin-specific gene and . Taken together, our results suggested that MrMYB6 might negatively regulate anthocyanin and PA accumulation in Chinese bayberry.
花青素和原花青素（PAs）是杨梅中的重要类黄酮，它们在果实颜色形成中发挥作用，并具有多种促进健康和预防疾病的功效。为了研究杨梅中它们生物合成的调控机制，我们分离并鉴定了一个4亚组的MYB转录因子（TF），MrMYB6，并通过序列分析发现MrMYB6与其他花青素和PA生物合成的MYB共抑制因子具有相似的抑制结构域。基因表达结果显示，在杨梅成熟后期，MrMYB6的转录本与花青素和不溶性PA含量呈负相关，也与花青素生物合成相关基因以及PA特异性基因如[具体基因名称缺失]和[具体基因名称缺失]的基因表达呈负相关。此外，在烟草中过表达MrMYB6抑制了[具体基因名称缺失]、[具体基因名称缺失]和[具体基因名称缺失]的转录水平，导致烟草花中花青素和PAs水平下降。我们进一步发现，MrMYB6与MrbHLH1和MrWD40-1相互作用形成功能复合物，直接抑制PA特异性基因[具体基因名称缺失]和[具体基因名称缺失]以及花青素特异性基因[具体基因名称缺失]和[具体基因名称缺失]的启动子活性。综上所述，我们的结果表明MrMYB6可能对杨梅中花青素和PA的积累起负调控作用。
