Differences among all living things is driven by mutations. A simple change in the nucleic acid position within the DNA or RNA code can affect the structure of the protein being produced by a gene. That protein’s function among the several affecting production of some cellular process ultimately can be significant to the organism’s appearance or function. Every cell division is vulnerable to such slight changes in these types of slight changes in DNA. Those occurring during cell division of cells not involved in reproduction result in a group of cells differing from adjacent cells is called a chimera. It could result in a distinct streak in a leaf of one corn plant. Most chimeras do not continue to the next generation if the mutation was not present in the nuclei of the reproduction cells.
Mutations during meiosis are the main source of genetic diversity in organisms with two sets of chromosomes (diploids). Multiple mutations accumulate over generations resulting in distinctive characteristics among genotypes. Organisms with shorter life cycles are likely to gain diversity quicker. Selection of those best fitting an environment can include variations utilizing different physiological processes to accomplish this success. The randomness involved in mutations also includes differences that we humans do not know are of necessary function but simply are present.
These genetic differences among corn varieties can be detected by comparing plant structures, proteins or DNA. Professional Seed Research, Inc. compares leaf structures of three leaf plants when growing in uniform environments, allowing the distinction between expected phenotype versus those produced by the wrong parent, such as selfing or pollen from wrong male parent. Careful observation of mature plants also makes this distinction. In all of these methods, we detect diversity but not necessarily significant differences in desired function of the plant.
Although diversity is frequently random or at least without recognized useful function, we use it as a means to detect distinct varieties. Taxonomists specialize in observations of these differences to define species. Humans use phenotype expression of facial characters to distinguish among individuals. It is best, at this point, not to comment about those human characteristics most desirable to me, but just as with corn, some diversity due to genetic diversity would seem less functional than others.
Among the 30000-40000 genes in corn, some mutations have occurred over time to be useful to humans and some are distinctive but not obviously useful in today’s environments. In general, we should celebrate diversity in all organisms. Mutations are great!
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.