Integrated Analysis of Physiological, Transcriptomic, and Metabolomic Data Reveals the Drought Response Mechanism in Cabbage

Under global climate change, cabbage (Brassica oleracea var. capitata), a major vegetable crop, is increasingly exposed to intermittent and fluctuating drought stress. A multi-level investigation of its adaptive strategies under water-deficit conditions is therefore essential for a comprehensive understanding of drought tolerance and for accelerating genetic breeding programs. In this study, the drought-resistant cultivar ‘ZG-628’ and the drought-sensitive cultivar ‘ZG-21’ were selected based on seed germination indices. Integrated physiological measurements, transcriptomic profiling, and metabolomic analyses were conducted to systematically compare their responses to drought stress. The results showed that the drought-resistant genotype ‘ZG-628’ maintained better water status, exhibited higher antioxidant enzyme activities, and accumulated greater levels of osmotic regulators under drought conditions. In addition, ‘ZG-628’ preserved higher chlorophyll content and photosynthetic efficiency than the sensitive genotype. At the molecular level, ‘ZG-628’ primarily responded to drought through key components of the abscisic acid (ABA) signaling pathway, including PYL, PP2C, and SnRK2. Metabolomic analysis further revealed preferential accumulation of flavonoids and ABA-related metabolites ‘ZG-628’, accompanied by specific activation of the “flavonoid and flavonol biosynthesis” pathway. Integrated multi-omics analysis indicated that plant hormone signal transduction was the most significantly enriched pathway among drought-responsive differentially expressed genes. Overall, this study systematically elucidates the coordinated multi-omics mechanisms underlying drought resistance in cabbage and provides both a theoretical basis and potential molecular targets for breeding drought-tolerant cabbage varieties.