Genome-wide association and genomic prediction models of tocochromanols in fresh sweet corn kernels

Sweet corn (Zea mays L.), a highly consumed fresh vegetable in the United States, varies for tocochromanol (tocopherol and tocotrienol) levels, but makes 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 vte4 (γ-tocopherol methyltransferase) and α-tocopherol content, along with vte1 (tocopherol cyclase) and hggt1 (homogentisate geranylgeranyltransferase) 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 toc...