Ultraviolet-B-induced MdWRKY71-L expression regulates anthocyanin synthesis in apple

Anthocyanin plays critical role in plant secondary metabolism. Although many transcription factors (TFs) that participate in the anthocyanin biosynthesis pathway have been characterized, many have yet to be reported. In the study, we cloned a WRKY Group IIc TF in apple (Malus × domestica), MdWRKY71-L, which localized to the nucleus. The overexpression of MdWRKY71-L promoted the accumulation of anthocyanin in apple calli. MdWRKY71-L mainly stimulated this accumulation through interacting with the promoters of MdMYB1 and MdUFGT. In addition to plant genotype, the synthesis of anthocyanin is also affected by external factors, such as ultraviolet-B radiation. Ultraviolet-B exposure induced MdWRKY71-L expression and MdWRKY71-L promoted the expression of MdHY5 by interacting with its promoter. Our research provided new insights into how WRKY TFs participated in the ultraviolet-B signaling pathway to regulate the accumulation of anthocyanin in apple.