Corn kernel embryo axis
A mature maize kernel is composed of endosperm and embryo surrounded by the pericarp. The embryo has three types of meristems. A root meristem, a shoot meristem and lateral meristems. The initial lateral meristem located at the base of the shoot develops in the early stages of kernel to become the scutellum. The next lateral meristem becomes the first leaf tissue to emerge from the soil. This sheath-like tissue wraps around the other shoot tissue. The next 4-5 leaf meristems are also present in the mature corn embryo, each produced on alternate sides of the shoot. The fact that the coleoptile meristem is located very near and on the same side of the shoot as the scutellum meristem supports the hypothesis that it, like the scutellum is an extension of the same single cotyledon. Kaplan D. R
. (1996). Early plant development: From seed to seedling to established plant. In Principles of Plant Morphology, Chapter 5 (Berkeley, CA: Copy Central, University of California, Berkeley)
The apical meristem of the corn embryo shoot maintains a small group of cells programed to divide and eventually producing new specialized cells. Genes in all embryo cells are inherited from both the male and female parent. Mitochondria and plastid genetics are from the mother plant only. Position on the axis, probably in relation to the attachment to the cob on the mother plant, determines that genes turned on in embryo cells furthest away become shoot meristem and those closest to the base produce root cells. The tissue between the two is regarded as the hypocotyl. This becomes the site of most cell elongation that pushes the shoot enclosed by the coleoptile to exposure to light above the soil. It is also the embryo area of attachment by the scutellum and thus the location for movement of nutrients from the endosperm after digestion in the scutellum into the growing root and shoot cells during germination.
The mature corn kernel includes nutrients in the endosperm, cytoplasmic capability in the scutellum to digest and move these nutrients and embryo axis components of meristems ready to go when environment is available. A more technical summary of the shoot apical meristem can be found at http://www.plantcell.org/content/24/8/3219#ref-list-1
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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.