One of the more challenging concepts in agricultural science is how to study a very small aspect of the corn plant or a pathogen of corn and yet put it in the perspective of the affect on performance in a cornfield. Technologies that allow the studies of DNA code for a specific gene in corn are making remarkable additions to our understanding of a specific function in a corn plant. Specific genes associated with different single genes for resistance to the northern leaf blight fungus can be identified by molecular analysis tests. Of course, the fungus, without the ability to do molecular testing (LOL), nearly always has the genetic variability to take competitive advantage over others of its species to block the resistance component and cause the disease. At least 5 single genes in corn have been identified that result in limitation in northern corn leaf blight, generally by not allowing the fungus to produce spores and spread within the field. And, the fungus population is known to have at least 5 genes to overcome each of these genes. Selection pressure for increasing the frequency of such genes in the pathogen population is pretty great when the resistance gene inhibits reproduction in individuals lacking these genes.
We are witnessing this with insects and weeds as well. We can celebrate the attributes of genetic variability but also need to be aware that it sometimes works against our interests as well.
It is a problem for the grower of corn, the breeder selecting the next new hybrid, and the pathologist analyzing specifics of a particular disease to interpret data from small studies or observations into predicting how that will affect the performance in a specific 80-acre cornfield next year. Probably all of us get excited to learn some new thing about corn but we can never forget that dynamics of growing corn in environments within a single field, let alone everywhere the crop is grown, is really, really complex.
We all want to simplify but that is not reality of agriculture. Just as in many other aspects of life, despite our desire for things to be simple, it is not. Perhaps someone should mention this to politicians.
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.