Sorghum Germplasm Resources Characterization and Trait Mapping

Sorghum is the fifth most important cereal crop mostly grown for food, feed, fodder, and bioenergy purposes, and a staple for over 500 million resource-poor people in marginal environments. Globally, over 236,000 sorghum germplasm accessions have been conserved in genebanks, of which the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), India and the Plant Genetic Resources Conservation Unit, Southern Regional Plant Introduction Station, University of Georgia, USDA-ARS, together conserve about 32 % of the total global sorghum collections. Germplasm diversity representative subsets such as core and mini core collections and a genotyping-based reference set have been established in sorghum providing access to large diversity. The sorghum mini core collection established at the ICRISAT is being widely used for identification of sources for resistance to various biotic and abiotic stresses, and for agronomic and grain nutritional traits. Large genetic and genomic resources are available in sorghum, and resequencing of diverse germplasm resources including the mini core collection and wild and weedy relatives will provide researchers opportunities to relate sequence variations with phenotypic traits of interest and their utilization in sorghum improvement. Genomewide association mapping studies have identified genomic regions that are associated with important agronomic traits and resistance to biotic and abiotic stresses. High-throughput phenotyping platforms/technologies are required for precise phenotyping to attain greater genetic gains. The current status of germplasm, its characterization and utilization has been summarized in this chapter