Anthocyanins, a major class of compounds derived from the flavonoid pathway, are important pigments of apple fruit. They can also prevent certain diseases and are beneficial to human health. Fruit pigmentation is a key quality trait that influences consumer preference; therefore, it is of great importance to investigate its regulatory mechanism. Here, we identified a MYB transcription factor (TF), MdMYB114, whose transcript level increased in the skin of the deep red apple fruit. It was determined to belong to the R2R3-MYB TF family and was localized in the nucleus. MdMYB114 overexpression led to anthocyanin accumulation in apple calli. MdMYB114 was not able to form an MBW complex but could enhance anthocyanin biosynthesis and transport by directly binding to the promoters of MdANS, MdUFGT, and MdGST to promote their expression. In addition, multiple assays revealed that MdbZIP4-like, a basic leucine-zipper TF, could directly bind to the MdMYB114 promoter to enhance its expression. Taken collectively, our results provide evidence that MdMYB114 is a positive regulator of anthocyanin biosynthesis and transport and it functions downstream of MdbZIP4-like in apple fruit.

中文翻译：

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MdMYB114 调控苹果果实中 MdbZIP4 样下游的花青素生物合成和功能

花青素是类黄酮途径中的一大类化合物，是苹果果实的重要色素。它们还可以预防某些疾病，对人体健康有益。水果色素沉着是影响消费者偏好的关键品质特征；因此，研究其调控机制具有重要意义。在这里，我们确定了一种 MYB 转录因子 (TF)，MdMYB114，其转录水平在深红色苹果果实的果皮中增加。它被确定属于 R2R3-MYB TF 家族并定位于细胞核中。MdMYB114 过表达导致苹果愈伤组织中的花青素积累。MdMYB114 不能形成 MBW 复合物，但可以通过直接结合 MdANS、MdUFGT 和 MdGST 的启动子来促进它们的表达，从而增强花青素的生物合成和运输。此外，多项分析表明，MdbZIP4 样（一种基本的亮氨酸拉链 TF）可以直接与 MdMYB114 启动子结合以增强其表达。总的来说，我们的结果提供证据表明 MdMYB114 是花青素生物合成和运输的正调节剂，它在苹果果实中的 MdbZIP4 样下游起作用。