Cells of the corn plant are the source of the plant structure and function. Converting light energy into chemical energy allows for growth and production of cell structures and chemical compounds allowing for all of living cell function. The totality of construction and function of the plant is determined by its DNA and interaction with environment. Ultimately, however, the movement within the plant of different cell products requires communications among the cells.
Movement of water within the plant is mostly made by simple physical principle of diffusion and osmosis. I recall a plant physiologist professor many, many years ago illustrating by sharing a story of being on a mountain road in a discussion with wife whether they were going uphill or not. He claimed he got out of car, poured water on the road and declared that water runs downhill! Water moves from a high concentration to a low concentration, such when diluted by sugar. That principle applies to movement of minerals and compounds as well, if they can make it through barriers such as cell membranes.
Hormones are actively involved with movement of cell products. Four notable groups of hormones are auxins, gibberellins, cytokinins and abscisic acid. Each is associated with different functions in the plant.
Auxins, such as indole acetic acid (IAA), affect cell elongation. Produced in the apical meristem it is associated with initial elongation of the stem tip. Absence in the lateral buds at base of each corn leaf, prevents branching. Removal of the apical meristem allows production of more auxin in lateral buds and consequential branching of the corn plant.
Gibberellins, such as gibberellic acid, promotes elongation of the cells in the stem but not in the apical meristem.
Cytokinins promote cell division in the meristems such as in the newly pollinated embryos. Zeatin is a cytokinin in corn embryos.
Abscisic acid inhibits cell growth. It is most active in developing the restriction of flow of more carbohydrates into the mature grain, causing the cells at base of kernel to form a ‘black layer’.
It is not known completely how these hormones cause these affects. It is mostly assumed that they are acting with cell DNA but some reactions, such as auxin causing roots of a germinating seed to turn to go downwards because cells on one side elongate more than those on the other side, seems too quick to only be reacting with DNA. Regardless mechanism, plant hormones are essential participants in the communication among corn cells.
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.