Germinating cell activity
The corn ‘seed’ appears as a single entity, but its parts have distinct origins and functions. The outer layer, the pericarp, is completely derived from the female parent and does not include genetics from the male parent. Immediately inside the pericarp is a product of the union of both parent. Aleurone cells are biologically active and include anthocyanin and carotenoid pigments affecting the color of the corn kernel. Pericarp and aleurone cell layers surround the the embryo and and endosperm of the corn kernel.
Most of the grain’s carbohydrate is stored in the endosperm. The embryo includes tissue adjacent to the endosperm called the scutellum that is rich in mitochondria and therefore ready to produce the energy needed to make enzymes such as amylases that break down the starch into it’s glucose components that will be moved to the other embryo cells.
Mitochondria show only slight activity in the dry seeds. Many apparently are only partially formed but a little respiration is occurring. However, once exposed to water, and the seed imbibes, the cells and its components, including mitochondria, swell. Partially formed mitochondria are not only activated but gain the more membranes needed to get the glucose transformed into the chemical energy needed for germination.
Studies have shown that temperatures affect this transition. Not surprising to anyone experienced with growing corn, the mitochondrial activity is higher at 77°F than at 57°F. Some of that activity is responsible for the membrane reproduction and repair not only in mitochondria but other membranes in the cells of scutellum and other embryo cells.
Another site of activity in cells of the embryo are the ribosomes, also inherited from the female parent. Ribosomes are the site of protein manufacturing. RNA molecules, as coded by the nucleus DNA, migrate through the nuclear membrane to ribosomes in the cell. Chemically energy from the mitochondria provide the power for import and combination of amino acids in the ribosomes for production of proteins to become the enzymes and structure of cell replication and growth in the germinating seed.
A lot of things are going on in that seed after it begins germination.
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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.