Integrated transcriptome and metabolome analysis revealed differential drought stress response mechanisms of wheat seedlings with varying drought tolerance

Wheat (Triticum aestivum L.) is a staple crop frequently enduring drought stress, significantly impacting its quantity and quality. Therefore, elucidating the underlying mechanisms of wheat's drought stress response is crucial for developing drought-tolerant varieties through molecular breeding techniques. This study analyzed the transcriptome and metabolome of wheat seedlings with varying drought tolerance (drought-tolerant T13, control CK, and drought-susceptible T2) under drought stress. Results suggested that T13 and T2 had partially similar drought stress response mechanisms. But the mainly drought response mechanisms in T13 (accumulated flavonoids and phenolic acids) was different from T2 (accumulated alkaloids). Integrated metabolome and transcriptome analyses demonstrated significant up-regulation of most flavonoids and phenolic acids biosynthesis-related metabolites and genes (HCT, FLS, CHS and F3'5'H) in T13 under drought stress. These results indicated that flavonoids and phenolic acids metabolisms were associated with wheat seedling's drought resistance, with their biosynthesis-related differentially expressed metabolites and genes possibly being key factors underlining the difference in drought tolerance. Thus this study enhances our understanding of wheat seedling's drought response mechanism, providing valuable insights for breeding drought-tolerant wheat cultivars.