Physiological characterization and gene mapping of a novel cuticular wax-related mutant in barley

Background: Cuticular wax is a type of lipid covering the surface of plants, which is directly related to crop stress resistance. Thus, it is important to study wax-related genes and their regulatory mechanism in wax biosynthesis pathway for improving stress resistance.Results: In this study, a wax-deficient barley mutant barley cuticular wax1（bcw1）was identified, and genetic analysis indicated that the trait was controlled by a single recessive nuclear gene. Phenotype observations showed that the tubule-shaped waxy crystals covering the sheath and stem epidermis of mutants disappeared, but there was no significant differences were detected in the leaf epidermis between mutant and wild type. Water loss data confirmed that the cuticular waxes and cutins improved plant resistance to drought stress. By combining the bulk segregant analysis (BSA) and specific locus amplified fragment sequencing (SLAF-seq) strategy, the wax-related gene BCW1 was located on chromosome 2 with a total length of 15.10 Mb. No cuticular wax-related genes have been reported in the regions, indicating that BCW1 is a novel gene that plays roles in cuticular wax biosynthesis and wax crystals formation.Conclusions: The research showed that mutation of BCW1 did not affect the crystal shape or cutin formation outside the leaf surfaces, but decreased the wax and cutin accumulation outside stems and sheaths. Therefore, our work provides the basis for the cloning of BCW1 and studying of the crystal self-assembly mechanism.