Epicuticular Wax Morphology of Bloomless (bm) Mutants in Sorghum bicolor

Sorghum bicolor mutants for cuticular wax production provide a model system for analysis of epicuticular wax (EW) physiology, biochemistry, and genetics. Mutants produced from seeds treated with the chemical mutagens diethyl sulfate (DES) and ethyl methanesulfonate (EMS) were selected in the M₂ generation and self-pollinated to produce near-isogenic mutants of two classes: bloomless (lacking visible EW) and sparse bloom (possessing little visible EW). Scanning electron microscopy was used to further divide 33 selected lines into 14 unique classes based on altered EW structure. Mutations have affected the structure of cork silica (CS) cell associated EW or both CS cell and cuticle EW. The resulting spectrum of altered EW structure indicates unique alterations in EW biosynthesis or deposition which may correlate with specific EW alleles and loci within the Sorghum genome.