Genome-wide identification of R2R3-MYB transcription factor family in Styphnolobium japonicum and their function roles in flavonoid biosynthesis during the flower development

Styphnolobium japonicum L., an important leguminous tree species, is widely recognized for its ecological, cultural, and medicinal values, particularly its rich flavonoid profile, which underpins its extensive therapeutic applications. This study presents a comprehensive genome-wide investigation of R2R3-MYB transcription factors (TFs) in S. japonicum, with a focus on their regulatory roles in flavonoid biosynthesis. Based on the systematically analyzed the expression patterns of candidate R2R3-SjMYB TFs and key structural genes involved in the flavonoid biosynthesis pathway during different stages of flower development, our findings revealed the pivotal regulatory roles of R2R3-SjMYB TFs, such as SjMYB85, SjMYB113, SjMYB89, and SjMYB158, in modulating the biosynthesis of rutin and quercetin, both of which possess potent antioxidant properties. Notably, protein-protein interaction (PPI) analyses and promoter-binding predictions indicated a direct regulatory mechanism, wherein R2R3-SjMYBs activate structural genes like SjF3H, Sj4CL, and SjANR, thereby orchestrating key branches of the flavonoid biosynthetic network. This study advances our understanding of the transcriptional regulation underlying flavonoid biosynthesis in S. japonicum and provides a robust framework for utilizing these genetic resources in the development of high-value medicinal and functional plants. The insights gained have profound implications for biotechnological applications, including metabolic engineering and selective breeding strategies, aimed at enhancing the production of bioactive compounds.