As the early corn breeders moved a wild plant (Teosinte) into a grain crop with more carbohydrate storage in the seed, corn produced more starch than needed to produce the next generation. 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.
It is well established that the female parent of a corn hybrid is most closely related to ability to maintain high germination. The fact that mitochondria have their own DNA and are transferred to the seed only from the female is likely a major cause for the relationship to germination. Some studies have shown that differences in mitochondrial function under cooler temperatures are also related to the female parent as well. Other seed characters are also female parent related. A corn grain is a fruit with a thin pericarp, a female parent structure. Endosperm cells are formed with two female shots of DNA and one from the male suggesting that also may have some uneven female parent influence.
The germination stability of commercial hybrids is dependent upon the choice of female parents, often to the chagrin of corn breeders.
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.