Genetic Modification of Crops

Deborah Byrd has an interesting posting and discussion on GM crops for Africa on her EarthSky Blog. Note that there are about 50,000 genes in corn. Thus there are 50,000 places in which one gene can be substituted for another. Of course, there may be quite a few alleles available for any one gene. If one were to choose to change two and only two genes, there would be 2,500,000,000 ways to chose the two genes.

The point I am making is that there are many, many ways to change the genome of a plant variety. One can also change the expression of the gene having it produce more or less protein. One can introduce a new gene, or delete a gene. Indeed, it appears that much of the control that DNA exercises over plant behavior is not in genes at all, but in DNA that produces RNA that functions directly without being transferred into a protein.

Plant varieties used in agriculture are the result of thousands of years of selection. Most of the genetic changes one might introduce will not improve the variety's suitability for human use. The very complicated job of the plant breeder is to select from the many possible changes those that will in fact be beneficial. Recombinant DNA techniques can help the scientist in that effort, even taking into account the added difficulties of safety testing of the resultant varieties.

There are risks involved in accepting new varieties of a crop. Indeed, there are risks in accepting changes in the human diet. On the other hand, there are dangers of depending on the existing varieties in the face of increasing demand for food, climate change, environmental degradation, and evolving populations of pests and diseases. Not only that, there are real risks of limiting the techniques available to scientists to develop improved varieties. Good policy depends on informed balancing of those risks. The informed consensus is that developing nations need to allow scientists to use recombinant DNA techniques to develop improved food crop varieties.

The corn plants that made these honking ears of field corn contain genes to kill corn rootworm, a major pest of a major crop. Photo: Monsanto via The Why Files: Genetic Engineering