Virus genetics are very simple. They penetrate the genetically complex host cells, utilize the hosts metabolism to duplicate themselves and move on to another host cell. COVID 19 virus has 15 genes in its RNA. Humans have about 20000 genes in its nuclear chromosomes plus independent genes in some cell organelles such as mitochondria. Corn has about 40000 genes in its chromosomal DNA plus genes in chloroplasts and mitochondria. The human selected genes that allowed the development of modern corn from its Teosinte origin only involves 2-4 percent of the total genes in present corn varieties.
One marvels at the complexity of the interactions that are occurring within each cell of a corn plant as it not only absorbs light energy, translates it into metabolic energy for sustain growth and more metabolism. Meanwhile the corn plant is fending off potential invaders of insects and pathogens. Mutations in genetics of those invaders can overcome the simple detection method of the host that triggers the corn plant to produce metabolites to stop the pathogen. Human selection of more stable resistant corn has resulted in resistance inherited by several genes. Usually, 3-5 genes are involved in limiting a pathogen success in a corn variety. Occasionally a single gene in corn is effective but often only for a short time. The Ht1 gene for stopping Helminthosporium (Bipolaris) turcicum was useful in USA in late 1960s for about 15 years but eventually the mutants in the fungus produced metabolites escaping the Ht1 gene’s products, making use of the gene no longer effective.
Adaptability of corn to multiple environments is due to the large genetic resource among those 40000 genes. Corn being an annual plant, separation of male and female flowers and abundant genes for selection has allow humans to desirable traits. Mutations and new mixes of genes from different backgrounds has allowed these selections to continue the increase in grain production by this plant. Research in the nature of the corn genetics continues as molecular methods discern more about corn genes. One article summarizing current status of corn genes can be found at https://www.cell.com/plant-communications/pdf/S2590-3462(19)30010-0.pdf.
At the same time that the complexity stimulates the research interest for some to explore with their molecular research, the simple pollination of the corn species, and more complex testing for desirable hybrids by those making selections for current environments has allowed participation of a large number of humans in improving this crop.
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.