Advancing provitamin A biofortification in sorghum: Genome-wide association study of grain carotenoids in global sorghum diversity

Authors: BURGOS, CLARA-CRUET - Kansas State University; Cox, Sarah; Ioerger, Brian; PERUMAL, RAMASAMY - Kansas State University; HU, ZHENBIN - Kansas State University; HERALD, THOMAS - Retired ARS Employee; Bean, Scott; RHODES, DAVINA - Kansas State University

Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2020
Publication Date: 3/26/2020
Citation: Burgos, C., Cox, S.R., Ioerger, B.P., Perumal, R., Hu, Z., Herald, T.J., Bean, S.R., Rhodes, D.H. 2020. Advancing provitamin A biofortification in sorghum: Genome-wide association study of grain carotenoids in global sorghum diversity. The Plant Genome. 4. https://doi.org/10.1002/tpg2.20013.
DOI: https://doi.org/10.1002/tpg2.20013

Interpretive Summary: Vitamin A deficiency is one of the most prevalent nutritional deficiencies worldwide. Sorghum, a staple cereal crop for millions of people in regions with high vitamin A deficiency, contains significant natural variation of provitamin A carotenoids. Despite having a wide variability in carotenoid levels, most sorghum lines are naturally low in carotenoids. To identify genetic markers for use in sorghum breeding programs to increase the levels of carotenoids in sorghum, a genetically diverse sorghum population was analyzed for carotenoid content and composition. This information was used to identify genetic regions related to carotenoid content. The analysis found several quantitative trait loci (QTL's) for carotenoids that can be used in biofortification research to improve the nutritional quality of sorghum grain.

Technical Abstract: Vitamin A deficiency is one of the most prevalent nutritional deficiencies worldwide. Sorghum, a staple cereal crop for millions of people in regions with high vitamin A deficiency, contains significant natural variation of provitamin A carotenoids. We quantified ß-carotene, a-carotene, lutein, zeaxanthin, and ß-cryptoxanthin in a genetically diverse sorghum association panel using high-performance liquid chromatography (HPLC), and conducted a genome-wide association study (GWAS) of grain carotenoids to identify genes underlying carotenoid variation. Using multiple models, GWAS identified several quantitative trait loci (QTL) for each carotenoid trait, some of which colocalized with known carotenoid pathway genes that have been identified in other species. Of particular interest, a maize (Zea mays) ortholog of zeaxanthin epoxidase (ZEP) was identified as a major gene involved in sorghum grain zeaxanthin variation. The high carotenoid germplasm and QTL identified in this sorghum panel can be used in biofortification efforts to improve the nutritional quality of sorghum grain.