Multi-omics reveal UV-B irradiation plays positive roles in flavonoids and phenolic accumulation in Glycyrrhiza inflata

Glycyrrhiza inflata is a perennial herb with extensive pharmacological applications (e.g., immune regulation, gastric protection, and hepatoprotection). The roots are traditionally valued while the leaves also represent a significantly underutilized resource rich in bioactive compounds, especially glycyrrhizic acid and liquiritin. Although UV-B irradiation is known to modulate growth, development, physiological processes, and specialized metabolites (including flavonoids and phenolics), its regulatory mechanisms governing plant growth and metabolic biosynthesis remain inadequately understood. In this study, a multi-omics approach was employed, integrating ultra performance liquid chromatography-electrospray ionization-mass spectrometry (UPLC-ESI-MS), RNA sequencing (RNA-seq), and quantitative real-time polymerase chain reaction (qRT-PCR) to analyze UV-B-induced changes in morphology, accumulation of bioactive compounds, and gene expression in G. inflata. Key findings revealed that appropriate UV-B exposure enhanced stress tolerance indicators (e.g., SOD, POD, MDA, and soluble sugar levels), stimulated the biosynthesis of metabolites (flavonoids and phenolics), and triggered differential expression of genes involved in flavonoid (e.g., CHR, CHS, and FLS) and phenylpropanoid synthesis (e.g., PAL, COMT, and PIF3). Integrated transcriptomic and metabolomic analysis confirmed a concordance between gene expression patterns and metabolite dynamics. These results elucidate UV-B-responsive mechanisms in G. inflata and demonstrate its potential efficacy in enhancing the biosynthesis of bioactive compounds.