||Sorghum has greater tolerance than the other major crops (rice, wheat, barley, and maize) to hot and dry environments; the profuse amount of epicuticular wax (bloom) on the sorghum plant plays an important role in protecting the tissues from abiotic stresses such as drought and ultraviolet light. However, the bloomless mutant, which has reduced levels of epicuticular wax, is not a preferred host of greenbug (Schizaphis graminum) and is resistant to sheath blight (Rhizoctonia solani Kuehn) (Kasuga et al. 2001). As greenbug and sheath blight cause serious yield losses, the bloomless phenotype is a useful trait for agricultural crops in the temperate zone and in relatively humid areas.Here, we used gamma irradiation to generate a bloomless (bm) sorghum mutant with normal growth but reduced epicuticular wax content. To directly identify the gene responsible for the phenotype, we applied massive parallel sequencing of RNA and compared expressed genes between the wild type and the bm mutant.