Cloning of Economically Significant Sorghum Mutant Genes

Mutations, occurring either naturally or induced, are permanent alterations of the nucleotide sequence in organisms. These alterations occurring throughout the evolution of a species are responsible for creating immense genetic diversity. Such natural variation generated by mutations has been selected and extensively utilized in crop improvement in several agronomically important crops. In sorghum, mutations producing key agronomic traits such as nonshattering, dwarfing, photoperiod insensitivity, improved protein digestibility, and brown midrib phenotype resulted in establishment of sorghum as the fifth major cereal crop of the world. In addition to successful utilization of these mutations in breeding, understanding the mechanistic basis underlying these traits is equally important to assist in trait advancement. Hence, mutations underlying important agronomic traits were identified using approaches such as positional or map-based cloning, candidate-gene approach, and whole genome sequencing. This chapter provides an overview of key sorghum mutations that resulted in evolution of sorghum as a major source of food, forage, and bioenergy. Additionally, cloning strategies used to identify the underlying mutations and mechanistic basis of the phenotype of interest are discussed. Identification of mutations underlying agriculturally important traits can assist in developing molecular markers to enable precise introgression of selected traits into elite inbreds used in sorghum improvement programs.