Within minutes of exposure to light, coleoptile cells, like other corn leaf cells, turn green, from chlorophyll production. This occurs within cell structures unique to plants called chloroplasts. These cell organelles, like mitochondria, are enclosed within their own membranes and have their own DNA. In fact, they have so much structure and chemical similarity to blue green algae (Cyanobacteria), chloroplasts are believed to have originated as a single event of a cyanobacterium gaining a symbiotic relationship within a single cell organism about a billion years ago.
Chlorophyll is a complex pigment that absorbs blue and red factions of light. A photon of light energy removes an electron from the chlorophyll molecule. This electron is transferred through a series of chemical reactions within the chloroplast until it ultimately ends up separating hydrogen from oxygen in water and combining hydrogen, carbon and oxygen molecules to make the carbohydrates for use elsewhere in the plant. Excess oxygen is released into the atmosphere.
Chlorophyll molecules are composed of carbon, hydrogen, oxygen, nitrogen and magnesium atoms. Genetics for the molecules is within the DNA of the chloroplasts and is inherited through the female seed parent of a hybrid. As the chloroplasts are exposed to light they are known to divide within cells and even to move within cells to become oriented to the light for best absorption of light. As an endophyte, they are dependent upon the cell for minerals and availability of carbon dioxide, but do produce their own enzymes.
Amazes me that as we see those green corn spikes emerging in the field, all of this is happening outside of our eyesight.
Visit us at the ASTA in Chicago, Dec 9-12 (booth G207)
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.