From molecules to field: Integrated insights into cuticle-mediated drought tolerance in plants.

Drought stress exacerbates non-stomatal water loss, which hinders agricultural growth and global food security. The cuticle, a layer of cutin, waxes, and other polymers, protects plants from the negative impact of drought. One crucial adaptation that has enabled terrestrial plants to survive and flourish in drought-prone regions is the development of cuticle structures. In this review, we (1) provide an overview of the molecular and enzymatic pathways involved in the biosynthesis of cutin and wax; (2) analyze important regulatory networks that control the formation of cuticles, such as abscisic acid (ABA) mediated signaling and transcription factors (SHN1/WIN1, MYB, NAC); (3) synthesis functional evidence of cuticle contributions to drought resilience across species; (4) evaluate how cuticle-related mutants and transgenic lines of genes such as ECERIFERUM1, Fatty Acyl-CoA Reductase 1 and Lipid Transfer Protein GPI-Anchored 22 (e.g., CER1, FAR1, LTPG22) change the composition of lipids and impact drought phenotypes; and (5) present lipidomic as a targeted phenotyping method to measure changes in very-long-chain alkanes, primary alcohols, and cutin monomers under water deficit. In Arabidopsis, camelina, cotton, rice, wheat, and turfgrass, we employ gas chromatography-flame ionization detection (GC-FID) for accurate detection and quantification of fatty acid content, and gas chromatography-mass spectrometry (GC-MS) for the qualitative and quantitative analysis of lipid components to identify lipid-remodeling patterns that are consistent across all of these plants and are associated with drought tolerance and barrier integrity. Finally, we discuss how to create "drought-smart" crops by quantitative trait loci (QTL) mapping, marker-assisted selection, CRISPR-Cas9 editing of KCS (3-ketoacyl-CoA synthase) and ERF (ethylene-responsive factor) genes, and overexpression approaches. This establishes the foundation for integrating cuticle biology with novel omics methods.