While we wait for the first signs of emergence from the soil with the coleoptile poking up to the light, the real action has been happening within the cells of the shoot and roots of the seed embryo. It is cell division and cell elongation that pushes the shoot tissue up and root down. That action is occurring as the cell organelles are activated
It is difficult to imagine 32000 genes distributed among the 10 chromosomes in the nucleus of a single cell within the embryo of the corn seed. But the microscopic cell also contains many other substances that contribute to cell function once it is activated with germination. Proteins and lipids contribute to the function of the outer plasma membrane surrounding the cell, but membrane-like structures also are intertwined within the cells. Endoplasmic reticulum is used to transport cell products. Ribosomes are attached to the outside of ‘rough’ endoplasmic reticulum. These ribosomes are the organelles in which RNA codes, originating from the DNA, are used to link the amino acids to form proteins. Adjacent endoplasmic reticulum is used to transport the newly formed proteins to sites in the cell appropriate for that protein’s function.
Mitochondria, independent organelles within the cell, are the site of transferring glucose molecules in the chemical energy used by other cell functions. These organelles, carried along in the egg cell from the maternal parent plant, have their own DNA for genetics but are dependent on the rest of the cell and nuclear DNA to provide the glucose, proteins and lipids for structure and function. This symbiotic relationship is in all animal, plant and fungal species, originating a few billion years ago and certainly is significant in corn performance. Mutations in the mitochondria DNA are the source of cytoplasmic male sterility, at least partly because of a genetic defect in the outer membrane of the mitochondria results in defective pollen production. Integrity of the membrane of the endoplasmic reticulum, ribosomes, mitochondria, nucleus and outer cell membrane after imbibition of water is essential to that early activation of the seed embryo and the emergence that we anticipate.
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.