The stem of a young corn plant, up to emergence of 4th or 5th leaf is below ground. The plant is supported by the tightly-wrapped leaf sheaths. Corn leaf sheath structure further supports this function as they are composed of vascular bundles with xylem tubes surrounded by lignin deposits. Vascular bundles carry out the important functions of xylem tubes for transporting water to the leaf blades and phloem tissue to move sugars to the roots and that growing point of the stem near the soil surface.
Leaf blades of these young plants develop more structures adapted to their photosynthesis. Genetics largely affects the shape of the leaf blade but each part is differentiated to carry out the functions. Epidermal cells include stomata that provide openings for absorption of carbon dioxide and release of oxygen molecules. Epidermal cells are often covered with a waxy cuticle functioning to reduce excessive loss of water. On the other hand, the movement of water through stomata and other small pores (hydathodes) on the edges of the corn leaf blade through evaporation and the cohesiveness of water molecules results in the pulling of water from the roots to the leaves through the xylem.
Majority of photosynthesis is carried out in the central part (mesophyll) of the leaf blade in the chloroplasts. These organelles, with their own genetics controlling much of their function and division, are the actual sites of photosynthesis. Other cell genetics control the movement of essential components of the photosynthetic process as part of the symbiotic relationship between chloroplasts and rest of the plant. Mitochondria, another symbiont with all living plant cells, are the sites for transferring the energy captured by the chloroplasts to useable forms of chemical energy allowing for more growth of young corn plant tissues.
Mitochondria in the meristematic tissue of the stem, still below the soil surface, also provide the energy for production of the nodal root system, greatly increasing the absorption of water and minerals, thus increasing the momentum for growth of the young corn plant.
Genes of the nucleus greatly influence the coordination of these cellular functions and structures within the constraints of the environment. Genetic diversity within the species is visible with close observation of these young corn plants but much more is happening out of our sight
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.