Functional characterization of StBBX19 and StBBX24 in UV-B-induced anthocyanin biosynthesis in pigmented potato

BBX transcription factors can respond to UV-B signals, promote plant photomorphogenesis, and regulate plant anthocyanin biosynthesis. Based on transcriptome sequencing analysis, this study analyzed the transcription factors of StBBXs under UV-B treatment and identified two differentially expressed genes, StBBX19 and StBBX24. We explored the protein structures, promoters, and phylogenetics of StBBX19 and StBBX24, speculating that they respond to UV-B treatment and regulate anthocyanin biosynthesis. We constructed overexpression vectors, YFP, and bimolecular fluorescence complementation vectors for the transient transformation of tobacco. The results suggest that StBBX19 and StBBX24 may not function as direct regulators of anthocyanin biosynthesis, but rather enhance anthocyanin accumulation through interaction with StMYB308. Still, after interacting with StMYB308, purple spots appeared on tobacco leaves, suggesting that the interaction between StBBX19, StBBX24, and StMYB308 increases anthocyanin content in tobacco leaves. This study provides significant evidence for the adaptation mechanism of plants under UV-B treatment and offers new insights for molecular plant breeding of pigmented potatoes.