Location: Grain Quality and Structure ResearchTitle: Genetic architecture of kernel composition in global sorghum germplasm Author
|Hoffman, Leo - Texas A&m University|
|Rooney, William - Texas A&m University|
|Boyles, Richard - Clemson University|
|Brenton, Zachary - Clemson University|
|Kresovich, Stephen - Clemson University|
Submitted to: BMC Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2016
Publication Date: 1/5/2017
Citation: Rhodes, D.H., Hoffman, L., Rooney, W.L., Herald, T.J., Bean, S.R., Boyles, R., Brenton, Z.W., Kresovich, S. 2017. Genetic architecture of kernel composition in global sorghum germplasm. BMC Genomics. doi:10.1186/s12864-016-3403-x.
Interpretive Summary: Sorghum is a cereal grain crop grown in dry areas around the world. Differences in the amount of protein, fat, and starch between sorghum types can be used to improve the nutritional quality of sorghum. The amount of nutrients in a sorghum type can be predicted based on growing region and genetic relationship to other sorghum types. Moreover, different gene versions identified in the study can be used to help quickly and efficiently breed sorghum for high or low levels of protein, fat, or starch.
Technical Abstract: Sorghum [Sorghum bicolor (L.) Moench] is an important cereal crop for dryland areas in the United States and for small-holder farmers in Africa. Natural variation of sorghum grain composition (protein, fat, and starch) between accessions can be used for crop improvement, but the genetic controls are still unresolved. The goals of this study were to quantify natural variation of sorghum grain composition and to identify single-nucleotide polymorphisms (SNPs) associated with variation in grain composition concentrations. In this study, we quantified protein, fat, and starch in a global sorghum diversity panel using near-infrared spectroscopy (NIRS). Protein content ranged from 8.1% to 18.8%, fat content ranged from 1.0% to 4.3%, and starch content ranged from 61.7% to 71.1%. Durra and bicolor-durra sorghum from Ethiopia and India had the highest protein and fat and the lowest starch content, while kafir sorghum from USA, India, and South Africa had the lowest protein and the highest starch content. Genome-wide association studies (GWAS) identified quantitative trait loci (QTL) for sorghum protein, fat, and starch. Previously published RNAseq data was used to identify candidate genes within a GWAS QTL region. Candidates identified for protein and fat variation include putative alpha amylase and fatty acid desaturase genes, which have previously been shown to be associated with grain composition traits. While there were no significant SNPs identified by the starch GWAS, the nearest starch-related gene to the top SNP (P = 0.4) is a putative trehalose-6-phosphate synthase gene. We identified promising sources of genetic material for manipulation of grain composition traits, and several loci and candidate genes that may control sorghum grain composition. This survey of grain composition in sorghum germplasm and identification of protein, fat, and starch QTL contributes to our understanding of the genetic basis of natural variation in sorghum grain nutritional traits.