Corn, being an annual plant, has opportunity for quick expression of mutations. Simple substitution for one of the nucleotide bases within the DNA for a gene, can result in an amino acid change in a protein critical to some physiological process in the plant. Many of these types of ‘errors’ made during meiosis do not cause meaningful or notable changes to the expressed corn phenotype, but a few have huge effects.
Opportunity for mutations to occur among the 40,000 corn genes, each gene having about 50-150 sets of 3 nucleotide bases makes genetic variability inevitable. Fortunately for us, this variability has been mostly beneficial, allowing for adaptation of this crop to multiple environments. Humans have been able to select those appropriate genotypes. Some rare mutants resulting in waxy and high amylose endosperm have special uses. White endosperm is another recessive gene that was due to a mutation in gene responsible for carotenoids in yellow kernels. Pure white kernels also require genes for colorless pericarp. Other obvious mutations involve different anthocyanin genes resulting in blue and red kernels.
Most mutations have resulted in less obvious differences affecting plant height, leaf uprightness, leaf width, root growth and direction, mineral uptake, general and specific disease resistance and even more subtle differences in photosynthesis and cellular respiration.
Mutations, although random, have given us a crop adapted to multiple human needs.
A review of the relationship of nucleotides to DNA and RNA can be found at:
A maize data base of corn mutants is maintained at maizegdb.org. This online site has an interesting summary of notable mutants at:
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.