Integrated multi-omics reveal mechanisms of awn variation in forage oats (Avena sativa)

Awns contribute to seed dispersal, grain yield, and drought tolerance, but their mechanisms in oats remain unclear. Using an awned mutant generated from cultivar Everleaf by sodium azide mutagenesis, we undertook phenotypic, physiological, and integrated multi‑omics analyses to dissect awn development and its link to drought tolerance. RNA-seq revealed more upregulated DEGs and DAMs (Differentially Accumulated Metabolites) in the mutant than in the wild type at the stem elongation and heading stages, with differential expression of AP2/ERF-ERF, WRKY, MYB, and bHLH transcription factors regulating downstream pathways. Integrated transcriptomic–metabolomic analysis identified 161 DEGs and 18 DAMs under coordinated regulation. Cytokinin biosynthesis was upregulated, increasing trans‑zeatin and cis‑zeatin riboside, along with increased cell division and awn initiation. Phenylpropanoid and flavonoid biosynthetic genes were also upregulated, elevating ferulic and sinapic acid and redirecting flux toward luteoforol, thereby supporting awn morphogenesis. Under drought stress, the awned mutant exhibited significantly higher antioxidant enzyme activity, photosynthetic performance, and grain yield than the wild type. Collectively, these results reveal a coordinated cytokinin–phenylpropanoid reprogramming that regulates awn morphogenesis and improves drought tolerance, providing a mechanistic framework for breeding high-yielding, drought-resistant cultivars.