Although many cells of the corn roots have the basic structures similar to other plant parts, there are significant differences appropriate to the root functions. Root cell production originates from active root tips, producing epidermal cells, intermediate parenchyma cells and vascular bundles complete with xylem and phloem tissue.
The important function of uptake of water and minerals occurs mostly through the youngest and newest cells near the root tips. This is enhanced by extensions from some epidermal cells called root hairs, vastly expanding the exposure to the root surface for absorption that occurs mostly by osmotic pressure. This is enhanced by diluting the water in root hair cells with sugars supplied ultimately by leaves and transferred through the phloem.
Root hair cell walls block large items, such as fungal mycelium, but smaller molecules pass through to the cell membrane that is selective in allowing entrance. Root hair extensions of the epidermal cells live for only a few days but as the root tip produces more new cells that produce new root hairs, the enhanced absorption of water and minerals continues. Auxin hormones are involved in the initiation of the root hairs. The short life is probably useful as the permeability enhances the potential for invasion by pathogens. After the root hairs disintegrate root cells increase the function of transporting to the xylem.
Of course, genetics influences the branching of roots, and production of root hairs. In addition to the multiple genes probably involved, a single root hairless mutant gene rth3 gene has been identified and in trials has shown to be associated with significant losses in grain yield. https://www.ncbi.nlm.nih.gov/pubmed/18298667/.
Lot of things happening in the corn plant that we don’t see.
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.