A single layer of cells immediately inside the pericarp is the aleurone. Contrary to the pericarp’s origin from the female plant’s ovary, the aleurone is derived from the pollinated ovule. It develops from the endosperm portion and thus from the contribution of one sperm nucleus combining with two haploid egg nuclei. Cells of the endosperm, including the aleurone cells is triploid, having three sets of chromosomes in their nuclei. It originates with other endosperm cells as they multiply after pollination. These cells surrounding the inner, starch filled endosperm cells, have an important role in seed germination, providing the enzymes to digest the starch in the rest of the endosperm into the glucose molecules.
Although only a single layer of cells, it can include 30% of the total proteins of the endosperm. It is also the location of pigment molecules influencing the color of the corn kernel. Pigment expression in corn kernels is mostly influenced by the carotenoid and anthocyanin pathways. A dominant gene (Y1) codes for synthesis of a protein in the carotenoid pathway for production of yellow pigment all of the endosperm, including the aleurone layer. If the female and male parents of a hybrid have the recessive version of this gene, and lacks recessives for the anthocyanin genes, the hybrid kernels will be white. However, if the male parent is yellow and the female parent white, the result will be the intermediate color between white and yellow. If both parents have the recessive gene of Pr1 the kernel will have purple anthocyanin pigment in the aleurone cells. The color will show as more blue pigment if the recessive carotenoid gene gives a white endosperm. Red kernels likewise are more intense with the absence of carotenoid pigments and presence of the recessive version of R1 gene for anthocyanin production.
Mutations of genes influencing pigments produced in the aleurone layer of cells was utilized a few thousand years ago by local cultures as corn was moved from that original Teosinte base. We use it today to make those colored corn chips.
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.