Genetics in the seed
More than 32000 genes on 10 pairs of chromosomes in each living cell of the corn seed embryo! Plus more genetics in each protoplastid, that later becomes the chloroplast, and each mitochondrion. Genes code for proteins that become enzymes participating in biochemical processes resulting in specialized cells for each corn plant structure, in hormones to direct the flow of sugars, and in the photoreceptor protein such as phytochrome that senses daylength and consequently affects flowering time in tropical corn. Some proteins are part of cell structure and some regulate the process for switching the gene to ‘on’ at the right time.
Living plant cells are surrounded by non-living cell walls. Inside these cells, proteins are major components of cell plasma membranes. The amino acid components, as coded in the DNA, have major roles in affecting which molecules enter the cells. This becomes especially important in active transport of sugars, for example, from lower concentration into higher concentration, in contradiction of usual passive transport from high concentration of molecules to lower concentration. Specific arrangements of specific amino acids allow the active transport of molecules across cell membranes.
Enzyme activity is also specifically related to allowing reactions to occur with less energy requirements and at fast speeds as they perform as catalysts. Such proteins often include more than 100 amino acids attached to each other but eventually folded in many ways allowing the pertinent charges on the enzyme molecules bind to a critical molecule assisting a chemical reaction to occur.
Cell function, and therefore, plant growth, is obviously dependent on protein structure. Those 32000 plus genes in corn, mostly dormant along with the seed when kept at low moisture, have a lot to do after seed germination begins. Mutations may have insignificant effects but some changes to just a few amino acids can cause major functional problems.
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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.