Population Genomics and Molecular Breeding of Sorghum

Sorghum bicolor (L.) Moench is a multipurpose crop worldwide, and it is used as a source of food, fodder, feed, and fuel. It is currently considered a promising alternative crop for generating bioenergy from sugar and lignocellulosic biomass. Sweet sorghum accumulates soluble sugar in its juicy stalk, being more appropriate for first-generation ethanol production, while biomass sorghum can be used for second-generation ethanol or bioelectricity production. For the development of superior sorghum cultivars dedicated to grain or biomass usage, breeding programs usually focus on several traits related to bioenergy, most of them exhibiting a quantitative inheritance. The genetic architecture and the environmental effects involved in the phenotypic expression of major sorghum traits are key factors to improve sorghum as a grain or bioenergy crop. In this context, understanding the availability of sorghum genetic resources, diversity, and molecular information at the RNA and DNA level is fundamental to perform effective selection strategies in sorghum. Population genomics research is providing key insights into genome structure, genomic variation, genetic diversity and population structure, origin and domestication history, and genetic architecture of adaptation to local climate as well as genomic-assisted selection and breeding in sorghum. In this chapter, we thoroughly discuss the progress made on these population genomics and molecular breeding aspects in sorghum and present future perspectives. Substantial research progress has been made on understanding the genetic basis of economically important sorghum traits through the identification of QTLs via linkage mapping and genome-wide association study (GWAS). Genomic selection or genome-wide selection has a great potential for increasing genetic gains in sorghum breeding programs for bioenergy and other traits.