Interactions between PtoYABBY5 and PtoMYB43 regulate flavonoid synthesis in Populus tomentosa

Flavonoids are secondary metabolites that serve as essential regulators of the growth, development, and adaptability of plants in response to various environmental stressors. Populus serves as a model system for research focused on woody plants. While a comprehensive understanding of the pathways that govern flavonoid biosynthesis is essential to effectively improve the quality and stress tolerance of wood, at present the factors that regulate this process in Populus have yet to be fully elucidated. Here, a candidate gene association analysis (P = 1.43 × 10−5) was employed to ultimately identify and characterize the flavonoid metabolite-associated YABBY transcription factor (TF) family member PtoYABBY5. At a functional level, PtoYABBY5 was found to interact with the key flavonoid biosynthesis-related TF PtoMYB43, a key TF for flavonoid biosynthesis. Dual-luciferase assays also revealed that the ethylene response regulator PtoERF72 positively regulates PtoYABBY5 expression. Overall, these data highlight PtoYABBY5 as an important and central component of the transcriptional machinery that controls the biosynthesis of flavonoids in Populus. By offering new insight into the regulation of flavonoid production at the transcriptional level, these results may provide new opportunities to improve the stress resistance and quality of wood derived from this economically important species of tree.