The aleurone layer of the corn kernel endosperm contains the water soluble anthocyanins, starch cells on the inner, yellow portion of this tissue is from carotenoid molecules. Two related molecules are xanthophylls and carotines. Xanthophylls tend to give a light yellow color and the carotenes a darker orange color to the endosperm. Function of these molecules in the corn kernel is not clear but they do have effects on the animals feeding on them. Carotenes can include beta-carotene, a precursor to vitamin A. Xanthophylls also contribute to the yolk color of chicken eggs.
Carotenoids are produced in a series of synthetic steps but is especially dependent on the presence of the dominant Y1 gene. If the recessive form of this gene, y1, is homozygous in the triploid endosperm, there is no yellow pigment and, consequently, the endosperm is white. People have selected varieties with pericarp-aleurone colors, or absent of those colors as well as endosperm colors probably mostly by personal and cultural choice. One can select for more carotene by simply choosing those ears with darker orange color. White corn also can be selected, although maintaining purity of white endosperm being inherited by recessive genes requires adequate isolation from any yellow varieties. Corn’s ability to cross pollinate with wide distribution of pollen has allowed continual production of genetic variability, and people integrated this into their cultures long before Europeans immigrated into the new world.
About Corn Journal
The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.