Characterization of increased cuticular wax mutant and analysis of genes involved in wax biosynthesis in Dianthus spiculifolius

Cuticular wax formation on the surface of plant leaves is associated with drought-stress tolerance. The identification of wax biosynthesis-related genes will contribute to the genetic improvement of drought resistance in plants. In this study, we characterize a novel Dianthus spiculifolius mutant with increased cuticular wax. The mutant exhibited stronger drought resistance as indicated by less leaf wilting and death, higher leaf relative water content and water retention capacity, and slower water loss and chlorophyll extraction than did the wild type during drought treatment. In the mutant leaves, 2 730 upregulated and 2 151 downregulated differentially expressed genes (DEGs) were identified by transcriptome sequencing. A wax biosynthesis pathway of the identified DEGs was significantly enriched. Finally, three key genes (DsCER1, DsMAH1, and DsWSD1) involved in wax biosynthesis were identified and verified by qPCR. These results suggest that differential expression of DEGs involved in wax biosynthesis may be associated with the increase in cuticular wax in the mutant. Taken together, our results help elucidate wax formation patterns in D. spiculifolius. Furthermore, the DEGs involved in wax biosynthesis identified here may be valuable genetic resources for improving plant stress tolerance through increased accumulation of cuticular wax.