Multi‐Omics Analysis Reveals Adaptive Strategies of Meconopsis horridula to UV‐B Radiation in the Qinghai‐Tibet Plateau

ABSTRACT Meconopsis horridula , an endemic medicinal and alpine horticultural species of the Qinghai‐Tibet Plateau, exhibits remarkable adaptation to high‐altitude UV‐B radiation. Despite its ecological and medicinal significance, the mechanisms underlying its UV‐B adaptation remain poorly understood. Here, we used a PacBio full‐length transcriptome as a reference, integrating RNA‐seq and metabolomic data from altitudinal populations, with field‐based transcriptomic and microbiome profiling under shade‐controlled UV‐B gradients, to elucidate UV‐B adaptive regulatory networks. KEGG enrichment and environmental correlation analyses highlighted flavonoid biosynthesis as a central pathway in UV‐B adaptation at high altitudes. Controlled UV‐B gradient experiments identified 10 conserved flavonoid biosynthesis genes, including chalcone synthase ( CHS ). Overexpression of CHS in Arabidopsis thaliana increased flavonoid content by approximately 1.2‐fold. Co‐expression analysis further revealed that CHS ‐associated regulatory factors mediate coordinated responses, including reduced light signalling, enhanced antioxidant capacity and suppression of defence genes and anthocyanin biosynthesis inhibitors. CHS , in coordination with immune regulation, modulates high‐centrality microbes, contributing to differential network regulation and microbiome stability. Enriched key microbes may mitigate the growth‐defence trade‐off under UV‐B stress through antimicrobial, growth‐promoting and antioxidant activities. Collectively, our findings reveal a flavonoid‐centred adaptation framework that deepens our understanding of UV‐B resilience in alpine plants and offers potential resources for crop improvement.