Richard E. Boyles, Brian K. Pfeiffer, Elizabeth A. Cooper, Bradley L. Rauh, Kelsey J. Zielinski, Matthew T. Myers, Zachary Brenton, William L. Rooney, Stephen Kresovich. Genetic dissection of sorghum grain quality traits using diverse and segregating populations. Theoretical and Applied Genetics (2016).
1. Department of Genetics and Biochemistry Clemson University Clemson, USA
2. Advanced Plant Technology Program Clemson University Clemson, USA
3. Department of Soil and Crop Sciences Texas A&M University College Station USA
4. Plants for Human Health Institute North Carolina State University Kannapolis, USA
5. Institute of Translational Genomics Clemson University Clemson, USA
There is a wide range of end-use products made from cereal grains, and these products often demand different grain characteristics. Fortunately, cereal crop species including sorghum [Sorghum bicolor (L.) Moench] contain high phenotypic variation for traits influencing grain quality. Identifying genetic variants underlying this phenotypic variation allows plant breeders to develop genotypes with grain attributes optimized for their intended usage. Multiple sorghum mapping populations were rigorously phenotyped across two environments (SC Coastal Plain and Central TX) in 2 years for five major grain quality traits: amylose, starch, crude protein, crude fat, and gross energy. Coordinated association and linkage mapping revealed several robust QTLs that make prime targets to improve grain quality for food, feed, and fuel products. Although the amylose QTL interval spanned many megabases, the marker with greatest significance was located just 12 kb from waxy (Wx), the primary gene regulating amylose production in cereal grains. This suggests higher resolution mapping in recombinant inbred line (RIL) populations can be obtained when genotyped at a high marker density. The major QTL for crude fat content, identified in both a RIL population and grain sorghum diversity panel, encompassed the DGAT1 locus, a critical gene involved in maize lipid biosynthesis. Another QTL on chromosome 1 was consistently mapped in both RIL populations for multiple grain quality traits including starch, crude protein, and gross energy. Collectively, these genetic regions offer excellent opportunities to manipulate grain composition and set up future studies for gene validation.