The Mechanism of Seed Priming with Abscisic Acid for Enhancing Cuticle Deposition Under Drought Stress: Phenotypic and Transcriptomic Insights

Plant cuticles are crucial for protecting plants from various environmental stresses. Seed priming with abscisic acid (ABA) enhances crop stress tolerance, but its molecular mechanisms in cuticular wax and cutin biosynthesis remain unclear. This study investigated ABA-priming’s role in boosting cuticular wax and cutin accumulation in sweet sorghum (Sorghum bicolor L.) using physiological and transcriptomic analyses. Abscisic acid priming increased leaf wax (37.7%) and cutin (25.6%) under drought, reducing water loss (9.8–36.6%) and improving leaf water content (28.4–120%). Transcriptomics identified 921 differentially expressed genes, including key fatty acid biosynthesis genes (ADH2, DES2, KAS2). Co-expression analysis revealed the synergistic regulation of wax and cutin biosynthesis by the abscisic acid and jasmonic acid (JA) pathways. Exogenous ABA and JA application confirmed their roles, with combined treatment increasing wax content by 71.7% under drought stress. These findings were validated in other sweet sorghum cultivars (DLS and ML8000), highlighting the potential of ABA priming as a universal strategy to enhance wax deposition in crops. Our study provides new insights into the molecular mechanisms underlying ABA-induced drought resistance and offers a practical approach for improving crop resilience in water-limited environments.