Genome‐Wide Association and Genomic Prediction Models of Tocochromanols in Fresh Sweet Corn Kernels
2019
Baseggio, Matheus | Murray, Matthew | Magallanes‐Lundback, Maria | Kaczmar, Nicholas | Chamness, James | Buckler, Edward S. | Smith, Margaret E. | DellaPenna, Dean | Tracy, William F. | Gore, Michael A.
Sweet corn (Zea mays L.), a highly consumed fresh vegetable in the United States, varies for tocochromanol (tocopherol and tocotrienol) levels but makes only a limited contribution to daily intake of vitamin E and antioxidants. We performed a genome‐wide association study of six tocochromanol compounds and 14 derivative traits across a sweet corn inbred line association panel to identify genes associated with natural variation for tocochromanols and vitamin E in fresh kernels. Concordant with prior studies in mature maize kernels, an association was detected between γ‐tocopherol methyltransferase (vte4) and α‐tocopherol content, along with tocopherol cyclase (vte1) and homogentisate geranylgeranyltransferase (hggt1) for tocotrienol variation. Additionally, two kernel starch synthesis genes, shrunken2 (sh2) and sugary1 (su1), were associated with tocotrienols, with the strongest evidence for sh2, in combination with fixed, strong vte1 and hggt1 alleles, accounting for the greater amount of tocotrienols in su1sh2 and sh2 lines. In prediction models with genome‐wide markers, predictive abilities were higher for tocotrienols than tocopherols, and these models were superior to those that used marker sets targeting a priori genes involved in the biosynthesis and/or genetic control of tocochromanols. Through this quantitative genetic analysis, we have established a key step for increasing tocochromanols in fresh kernels of sweet corn for human health and nutrition.
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