Soon after humans began the ancient practice of saving seeds, the process of selecting seeds likely soon followed. I can imagine the earliest agriculturists saving and replanting the seeds that were the biggest and came from the most robust plants. Those seeds were more likely to have better yields and resist frost or drought. Occasionally Mother Nature took care of the natural selection with weather events that left only those healthier, more resistant, seeds to be re-planted. Fruits that were bitter or small were cast aside for those that were sweeter and juicier. Grains or beans that were easier to store or preserve were favored.
As our ancient farmers became more sophisticated, they developed plant breeding as a better way of controlling the selection of seeds and plants. They discovered that they could actually breed a new plant variety by mixing the pollen of two closely related plants together. The aim of this “sexually crossed” manipulation was to produce favorable traits from both parent plants and exclude their unwanted traits in a new and better plant variety. These new varieties produced plants that suited different climate conditions, improved the taste and could better cope with disease and /or pests. Suddenly, through cross pollination, early farmers could better control their food supply.
Cross-pollination requires that the parent plants be compatible; they must be same species or a closely related species. Cross pollination remains an important breeding technique and it’s the primary way many plant breeders create new varieties.
Cross-pollination can produce haphazard results, so modern plant breeders looked for ways to ensure more consistent offspring from crossed plants, resulting in a technique called hybridization. The first step in creating a hybrid is to create two pure strains of plants by repeatedly inbreeding plants until a very stable strain is attained. For example, a wheat variety that produces high yields in one region may also be susceptible to a new disease. Another wheat plant may have very low yield but resistance to the new disease. Breeders can cross and back-cross these two parent wheat varieties and their progeny with the aim of combining the high yielding qualities from one parent with the disease resistance from the other parent.
Similar to conventional cross-pollination, the creation of hybrids is limited to compatible plants, usually the same or very closely related species. The well-loved varieties, such as Early Girl Tomatoes or Seedless Watermelons, are examples of hybrids.
We were humming along for hundreds of thousands of years, manipulating same species plants to do our nutritional bidding. Then in the early 1980s scientists created the first genetically modified organisms (GMOs) by inserting genetic material from one organism into the DNA of a completely unrelated organism, even a non-plant species! For the first time in natural and human selection there was now a method to transfer traits between vastly unrelated species. These resulting Genetically Modified Organisms (GMOs) are unstable combinations of plant, animal, bacterial and viral genes that cannot occur in nature or in traditional breeding.
The process of inserting genetic material is messy, and is in no way an exact, science. The process of insertion requires a gene “gun” that literally blasts the genetic material into the host plant cell. With this “gun” the genetic material inserts itself into the very chromosomes of the host plant. This process can result in unstable combinations. It is now possible to insert genetic material from species, families and even kingdoms, which could not previously be sources of genetic material for a particular species. We can even insert custom-designed genes that do not exist in nature. Because we have not co-evolved with these entities over the millennia, many may have negative or unforeseen effects.
To create “Bt corn,” for example, scientists incorporated genetic material from Bacillus thuringiensis, or BT (a toxic bacteria), into the DNA of corn plants to kill insects. Another wave of genetically modified plants is called “Roundup-Ready”. This makes the crops tolerant of the Roundup herbicide so that farmers can liberally spray the herbicide to kill weeds without damaging the resistant crop plants.
The predominance of GMO’s in our agricultural system has resulted in:
- Twenty-one species of new weeds that now show resistance to Round-Up and thus require the application of stronger herbicides.
- Widespread contamination from GM canola has eliminated organic canola in most areas of Canada. It’s almost impossible to segregate genetically modified and non-GM crops.
- Bt-resistant bollworms were found in cotton fields in Mississippi and Arkansas within seven years of the introduction of Bt cotton.
The age old tradition of plant pollination and hybridized plant breeding uses the genetic codes that have developed in gardens and fields, from plants and animals, developing over millions of years. GMOs are created by scientists in laboratories using high tech guns to force a new genetic entity into being. Before we stray too far into the divine area of plant and animal selection don’t you think we should step back and better understand the ramifications of what we are doing?
© 2013, Melody Meyer. All rights reserved.