MdMYB114 regulates anthocyanin biosynthesis and functions downstream of MdbZIP4-like in apple fruit

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.