Plant and animal genetics involve a complex involvement of DNA (deoxyribonucleic acid) with long chains of long chains of nucleic acids arranged in sets of 4. These chains are arranged as chromosomes and enclosed in a membrane. The DNA also codes for a related string of nucleic acids called RNA (ribonucleic acid). When a segment of the DNA is signaled to be ‘read’, that string of nucleic acids is transferred to messenger RNA. This mRNA moves through the nuclear membrane to a ribosome in the cell. Each set of 4 nucleic acids link specific amino acids to produce a specific protein. Thus, the DNA-RNA codes result in specific proteins produced in animal and plant cells. Many of these proteins function as enzymes for basic metabolism, ultimately resulting in structure and functions of plants and animals.
Viruses have simplified the process. Some have DNA and some only have RNA. They use the hosts cell’s ribosome for the protein production needed for the virus membrane. Current human epidemic caused by a coronavirus has its genetic code in mRNA. This sufficient to cause the host cell ribosomes to produce the few proteins needed for replication and further infection by the virus. One of those protein forms the ‘spike’ allowing the virus to penetrate the cell membrane. Viruses, such as this one, have self replicating RNA, simplifying the duplication process.
Viruses causing corn diseases have either RNA or DNA codes for duplication within host cells. Most appear to be RNA only genetic codes but a few, such as Maize Streak virus, has its genetic code in the form of DNA. Most corn virus require a vector to penetrate the plant cell walls, but after entering, they use the host cell’s cytoplasm to replicate. Host resistance depends upon successfully producing ‘antibodies’ to inhibit this replication process.
Let’s hope that the recently revealed vaccines for current human coronavirus that apparently involve a segment of the mRNA will successfully halt the ability of the virus to replicate.
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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.