view counter

Genetically Modified Organisms

Gene splicing is latest form of ­systematic plant breeding

What do I think about genetically modified plants? Here’s my answer to that question I so often hear.
    We have been genetically modifying plants for many centuries. We can blame the Austrian monk Gregor Mendel for initiating the science of plant breeding, which has resulted in improved quality and yields of vegetables, grains, fruit, flowers and ornamentals. It all started after Mendel crossed smooth peas with wrinkled peas and yellow peas with green peas. From these crosses, he concluded that there are dominant genes and recessive genes and introduced the possibility of hybrid vigor.
    The science he founded, genetics, has enabled farmers to produce ­higher-yielding crops, better-tasting fruit and vegetables, disease-resistant and disease-immune plants, plants resistant to insect damage.
    The next time you look at a seed catalog, look for the word hybrid in such terms as F1 hybrid and double-cross hybrid. All those hybrids are the result of systematic plant breeding.
    I saw hybridizing for myself in a course in Cytogenetics in which we used an old dental X-ray machine to irradiate germinating corn seeds. The exposure to different levels of radiation and periods of exposures resulted in numerous physical changes in appearances of seedlings that survived. The changes were due to genetic alteration. The previous semester class had performed the same experiment, then grown the corn to maturity. We grew seedlings from their corn and compared differences between our seedlings and the parents. Only a few of the seedlings resembled the parent. The majority expressed tremendous variations in appearance. Some changes were beneficial, while many were not. These experiments had been performed for many years, with a large collection of photographs for comparison.
    The science of genetics has made tremendous strides since Mendel. The helical structure of chromosomes was first reported in 1961. Since then scientist have identified the number of chromosomes in many organisms and the location of specific genes on those chromosomes. Using genetic engineering techniques, it is now possible to select specific genes and transplant them into desirable locations on specific chromosomes. This new method of cross-breeding has significantly reduced the time to generate improved varieties.
    Genetic modification in corn and soybeans has made those crops immune to damage from the application of glyphosate. This GMO significantly reduces the need to apply weed killers, which is beneficial. But only time will tell if GMOs will have any effect on quality and safety of these crops.
    There have been environmental problems with GMO cotton and other such crops. But with regards to vegetable crops, there is now a GMO sweet corn that can be grown without insecticides to control corn ear worm. There are raspberries that can be grown free of crown gall. These are just a few of many crop improvements that are the result of genetic engineering and the development of GMO crops.
    The Florida citrus industry is fading rapidly. Viruses are mutating at a faster rate each year, killing citrus trees. If the citrus industry is to survive, it will most likely depend on the development of plants genetically modified for immunity to these viruses. Once the gene that makes some plants immune to viruses can be located, there is a good possibility it can be transferred to citrus trees, thus making them immune.


Ask The Bay Gardener your questions at DR.FRGouin@gmail.com. Please include your name and address.