Inducible overexpression of MYB118-like gene improves anthocyanin production in Populus × canescens

Anthocyanins are secondary metabolites which contribute different colors to the leaves. Anthocyanin biosynthesis is regulated by MYB transcription factors, which have been extensively studied and characterized in a diversity of plants. In this study, we identified a novel MYB transcription factor MYB118L, from Populus 'Zhonghua Hongye', which showed an elevated accumulation of anthocyanin than Populus clone ZL-2025. Subcellular localization analyses revealed that MYB118L-GFP fusion protein was specifically located in the nucleus. Transgenic plants overexpressing MYB118L driven by the stress-inducible Rd29A promoter showed a significant increase in anthocyanin production, resulting in a red coloration of the leaves under drought stress conditions. These plants also exhibited higher expression levels of genes involved in anthocyanin biosynthesis compared to the wild type, suggesting that MYB118L positively regulates the expression of these genes. Y1H and dual-luciferase assays confirmed that MYB118L can directly activate the promoters of LAR1 gene. Our findings suggest that MYB118L is an essential transcription factor involved in the regulation of anthocyanin biosynthesis in poplar and could be utilized for genetic engineering of colorful tree species.