LlbZIP11 promotes anthocyanin accumulation in raised spots of Lilium leichtlinii by inducing LlMYB19S expression

Lilium leichtlinii is valued for its distinctive floral pattern, characterized by yellow tepals consisting of raised spots. These raised spots result from anthocyanin accumulation in the proliferating parenchymal and epidermal cells. However, molecular mechanisms regulating anthocyanin accumulation in raised spots remain uncharacterized. In this study, through a comparative transcriptome analysis of L. leichtlinii during raised spot formation, we identified LlbZIP11, a bZIP family transcription factor, as a candidate regulator of this process. Gene expression analysis revealed that the expression pattern of LlbZIP11 was similar to those of LlMYB19S, a MYB transcription factor involved in raised spot anthocyanin pigmentation, and anthocyanin biosynthesis genes. Functional validation demonstrated that LlbZIP11 positively regulates tepal spot formation and anthocyanin accumulation by upregulating LlMYB19S and anthocyanin-related genes. Dual-luciferase and yeast one-hybrid assays confirmed that LlbZIP11 binds to the LlMYB19S promoter to activate its transcription. These findings indicate that LlbZIP11 activates LlMYB19S, promoting anthocyanin accumulation in raised spots of L. leichtlinii. This study expands the understanding of anthocyanin regulatory networks in diverse floral pigmentation patterns and provides a foundation for further investigations into the mechanisms underlying raised spot formation in Lilium.