Binding cell walls
Corn pericarp cell walls are composed of polysaccharides, lignin, and protein compounds tightly bound together by another carbon-based chemical called dehydrodferulates (DFA). This is a common feature of many other C4 grasses including cells in leaves and stems. Increases in DFA has been associated with more resistance to ear damage from European, Mediterranean and tropical corn borers and grain storage insects. The feature of tightly binding the cell wall components have been shown to correlate with reduced insect damage in stalk and leaf tissue as well.
Fungi such as Gibberella zeae and Aspergillus species can invade stored grain under some conditions. These fungi not only can destroy grain quality but also can produce mycotoxins dangerous to humans and livestock. The tight binding of pericarp cells can ward off invasion of the grain, but some infection can occur through the silk previous to pollination. There is evidence that higher concentrations of DFA in the pericarp and aleurone is associated with a reduction in mycotoxin production. Apparently, the interaction of the fungal enzymes interacts with the cell walls, causing the release of ferulic acid that is believed to inhibit the ability of the fungus to produce mycotoxins.
The more we learn of the complexities involved in insect and pathogen resistance in corn along with the physical aspects of the corn plant’s structures it is easier to identify with the significance of field tests over multiple environments to select the best hybrid. It is not surprising that the corn genome includes at least 30,000 genes. We also should not be surprised when the ‘best’ hybrid in some environments is not the best in all environments
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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.