Institut des Sciences de la Vigne et du Vin, UMR 1287 Ecophysiologie et Génomique Fonctionnelle de la Vigne--INRA, Université de Bordeaux, 210 Chemin de Leysotte, 33882 Villenave d'Ornon, France.
Mol Plant. 2010 May;3(3):509-23. doi: 10.1093/mp/ssp118. Epub 2010 Jan 29.
Previous results indicated that in grapevine (Vitis vinifera), regulation of the flavonoid pathway genes by MYB transcription factors depends on their interaction with basic helix-loop-helix proteins (bHLHs). The present study describes the first functional characterization of a bHLH factor from grapevine named VvMYC1. This transcription factor is phylogenetically related to Arabidopsis bHLH proteins, which participate in the control of flavonoid biosynthesis and epidermal cell fate. Transient promoter and yeast two-hybrid assays demonstrated that VvMYC1 physically interacts with MYB5a, MYB5b, MYBA1/A2, and MYBPA1 to induce promoters of flavonoid pathway genes involved in anthocyanin and/or proanthocyanidin (PA) synthesis. Additionally, transient promoter assays revealed that VvMYC1 is involved in feedback regulation of its own expression. Transcript levels of VvMYC1 during berry development correlate with the synthesis of anthocyanins and PAs in skins and seeds of berries, suggesting that VvMYC1 is involved in the regulation of anthocyanins and PA synthesis in these organs. Likewise, transient expression of VvMYC1 and VvMYBA1 induces anthocyanin synthesis in grapevine suspension cells. These results suggest that VvMYC1 is part of the transcriptional cascade controlling anthocyanin and PA biosynthesis in grapevine.
先前的研究结果表明，在葡萄(Vitis vinifera)中，类黄酮途径基因的调控取决于 MYB 转录因子与其相互作用的基本螺旋-环-螺旋蛋白(bHLH)。本研究描述了葡萄中第一个 bHLH 因子 VvMYC1 的首次功能表征。该转录因子与拟南芥 bHLH 蛋白在系统发生上具有同源性，后者参与类黄酮生物合成和表皮细胞命运的调控。瞬时启动子和酵母双杂交实验表明，VvMYC1 与 MYB5a、MYB5b、MYBA1/A2 和 MYBPA1 物理互作，从而诱导参与花色苷和/或原花色素(PA)合成的类黄酮途径基因的启动子。此外，瞬时启动子实验表明，VvMYC1 参与自身表达的反馈调控。浆果发育过程中 VvMYC1 的转录水平与果皮和种子中花色苷和 PAs 的合成相关，表明 VvMYC1 参与这些器官中花色苷和 PA 合成的调控。同样，VvMYC1 和 VvMYBA1 的瞬时表达诱导葡萄悬浮细胞中花色苷的合成。这些结果表明，VvMYC1 是调控葡萄花色苷和 PA 生物合成的转录级联反应的一部分。
