Most of us interested in corn concentrate on appearance and performance of the whole plant. Some of us look a little more closely at a few features, such as seedlings or kernels. Only a very few corn people look at individual corn cells. Even with a light microscope magnifying at X1000 one can only see a faint image of the cell nucleus and a somewhat granular cytoplasm. Only with magnification by tens of thousands via the electron microscope do the structures within the cytoplasm become clear. Most of the living cell is dominated by long strings of a membranous structure called endoplasmic reticulum. This connects the import organelles of the cells. Multiple ribosomes, the sites in which, guided by RNA, imprinted with codes from the chromosomal DNA, attach amino acids to each other to form proteins.
Endoplasmic reticulum provides the pathway for these proteins to travel to important metabolic sites such as the mitochondria where glucose is processed into chemical energy in form of ATP. That process is dependent on the specific enzymatic activity linked to the arrangement of the amino acids in the protein. Endoplasmic reticulum structures also connect to chloroplasts where specific proteins assist in photosynthesis providing the glucose.
Endoplasmic reticulum also has a unique function in plants, unlike in animals, in that it can allow transport of proteins between cells through small pores in cell walls called plasmodesma. This allows plant cells to communicate despite presence of cell walls, that are absent in animals.
Endoplasmic reticulum is composed of lipids and proteins arranged as membranes, as with other membranes in cells, the precise arrangement of the specific lipids and proteins affects transport and movement across them. As with the membranes within mitochondria and chloroplasts, endoplasmic reticulum integrity is an essential part of the plant’s life. While we are concentrating on more visual characters of the corn plant, the real activity is happening in the cell cytoplasm at a microscopic and sub-microscopic level.
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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.