Corn nucleus includes 30000-40000 genes in its chromosomes. These 10 chromosomes are sorted and combined with the chromosomes of the other parent during pollination, both parents contributing to the hybrid. Cell organelles, such as plastids and mitochondria, have up to 100 genes in each small structure but these are not contributed by both parents during pollination. All organelle DNA is contributed by the egg cell.
Small mutations in the in mitochondria of the female parent can result in drastic affects on the plant. Such mutations resulted in cytoplasmic male sterility in CMS corn because in reduced the energy within pollen producing cells to make fertile pollen. This happens in T, C and S male sterility. Mitochondria function however is not completely dependent upon its own DNA, however, as nuclear genes in the cell also affect mitochondria function. Fertile pollen can be restored by cell nuclear genes such as the Rf1 and Rf2 that make T cytoplasm corn fertile. Similar fertility restoration for C and S cytoplasm sterility and be restored with presence of specific genes in the nuclei of the cells.
Plastids in cells function locations of starch storage and, in leaves, as the site of photosynthesis. These chloroplasts also have their own DNA with about 104 genes. Corn is among the few C4 plants the process photosynthesis in two distinct types of chloroplasts. Those in the main leaf cells do the initial process but final steps are carried out in chloroplasts in the bundle cells surrounding the cells. This is reviewed in Corn Journal blog of 7/14/2020 and 7/1/2020.
Corn hybrid genetics are mostly affected by the combination of specific nuclear genetic combinations of the two parent inbreds. Because only the female parent contributes the genetics of mitochondria and plastids choosing which parent is to be the female can have a drastic affect on some plant performance factors. This can be dramatic with some parents having reduced germinations. It is complicated and wonderful!
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.