The Genetic and Biochemical Frameworks Underlying the Energy Value of Sorghum.

Sorghum [Sorghum bicolor (L.) Moench] is a cereal that produces grains rich in carbohydrates, predominantly as starch.  This grain is important for providing the necessary calories to both humans in Sub-Saharan Africa and Southern Asia, and livestock in the United States.  Grain yield, composition, and digestibility all contribute to the amount of usable energy available for food and feed uses.  Genome-wide association studies (GWAS) are currently being utilized to identify regions associated with grain number, size, and composition that can be incorporated into breeding strategies to increase the overall energy value of sorghum per unit area and production input.  A diversity panel of approximately 400 accessions containing all five races as well as the intermediates was planted over subsequent years (2013-2014) in Florence, SC.  Abbreviated data from 2013 show significant variation in grain number per panicle (28-4024), thousand-grain weight (3.29-44.6g), starch content (60.15-73.15% dry matter),  among accessions.  Compositional data including starch, amylose, amylopectin, protein, fat and fiber, as well as in vitro starch digestibility, was analyzed using near infrared spectroscopy (NIRS).  Being able to manipulate the natural genetic variation of these compositional traits will allow breeders to tailor cereals for their intended end-use without compromising yield.  Understanding the genetic and biochemical frameworks of these complex, quantitative traits will prove beneficial by creating a platform to boost cereal grain yield and value to help compensate for the steady-increasing food demand.