MYB pathways that regulate UV-B-induced anthocyanin biosynthesis in blueberry ().

Ultraviolet-B (UV-B) promotes anthocyanin accumulation and improves fruit quality in plants. To explore the underlying network of MYB transcription factors that regulates UV-B-induced anthocyanin biosynthesis in blueberry (), we analyzed the response of transcription factor genes to UV-B treatment. Transcriptome sequencing analysis revealed that and expression were upregulated and were positively correlated with the expression of anthocyanin structural genes under UV-B radiation according to weighted gene co-expression network analysis (WGCNA) data. The VcUVR8-VcCOP1-VcHY5 pathway perceives UV-B signals and promotes the expression of anthocyanin structural genes by upregulating and or by regulating the VcBBXs-VcMYB pathway, ultimately promoting anthocyanin accumulation. By contrast, and were downregulated under UV-B treatment, and expression was negatively correlated with that of anthocyanin biosynthesis genes in response to UV-B. Analysis of -overexpressing and wild-type blueberry calli exposed to UV-B radiation revealed that represses UV-B-induced anthocyanin accumulation. Yeast one-hybrid and dual luciferase assays showed that the universal stress protein VcUSP1 directly bound to the promoter of . These results suggest that the VcUSP1-VcMYB4a pathway negatively regulates UV-B-induced anthocyanin biosynthesis and provide insight into UV-B-induced anthocyanin biosynthesis.