Integrated Transcriptomic and Metabolomic Analyses Reveal the Regulatory Drivers of Anthocyanin-Mediated Leaf Color Variation in Liquidambar formosana

Seasonal changes in leaf coloration are a key ecological and ornamental characteristic of Liquidambar formosana. To clarify the molecular basis of this process, we performed an integrated transcriptomic and metabolomic investigation comparing wild-type L. formosana (FX) with the autumn-red cultivar ‘Jinyu’ (JY). Leaves were sampled before and after the color transition. Analyses revealed distinct metabolic pathways driving coloration in each genotype. In JY, the red phenotype was primarily attributed to the activation of anthocyanin biosynthesis, characterized by coordinated upregulation of key structural genes (LfDFR, LfANS, LfBZ1) and significant accumulation of anthocyanins, especially pelargonidin derivatives. Conversely, FX exhibited enhanced flavonol biosynthesis and carotenoid/terpenoid metabolism, leading to greater yellow pigment accumulation and an orange-yellow hue. Weighted gene co-expression network analysis (WGCNA) identified a core module strongly correlated with anthocyanin content in JY, which was significantly enriched with transcription factors from the MYB, bHLH, and WRKY families. These results demonstrate that different L. formosana genotypes employ divergent metabolic strategies for autumn coloration, governed by specific transcriptional regulatory networks. This study provides crucial insights into pigment regulation in woody plants and offers valuable candidate genes for the molecular breeding of ornamental L. formosana cultivars.