Heavy work started in the seventies on altering corn, soybeans and alfalfa with genes from different plants and animals but it is only recently that products have started to emerge on the market. The early days were spent developing techniques and equipment to identify and map genetic material. This was followed by scientists identifying a significant amount of genes and finding what some of the genes do for a plant. Lastly, methods were developed to insert material into plants from other sources.
The work is easy to explain but the complexity involved in looking at DNA, extracting it, and putting it in another plant or animal is tremendous.
One problem is that you are working with very small stuff. Genes are much tinier than the tip of a pin, which requires some very precise machines and advanced chemistry to work with. Advancements in lab equipment and in organic chemistry have allowed gene technology to advance.
The next problem is isolating genes that you want to use. If you want to bring genes in from another source you must also know the gene makeup of the source. For example, you know the African sage brush is resistant to Gray leaf spot, you must find out which gene(s) in its makeup give it resistance.
The third problem is that the methods to move genes from one source to another are still very crude. The original method was to put a genetic material on the tip of a rifle slug and fire it onto the genetic material of the host. Other methods do exist now but they are not much more refined. In agriculture the preferred method is to put the gene in bacteria which will infect the host plant and transfer the gene.
The last major hurdle has been that there are limitations on which inbreds or varieties you can put genes into. Gene transfers currently don’t use whole plants, but single cells that must be made to regenerate back into whole plants. In corn only one inbred, A188 developed at the University of Minnesota, can do this and is used to add genes to corn.
Among also these problems the company doing the alteration must be able to show the government that this alteration is not a problem for the environment or a health risk.
To illustrate what's involved I've come up with a fictitious example to walk through:
The government wants to be able to use high salt soil for agricultural and your company, Acme genetics, decides to breed corn that can tolerate salt in the soil.
You start by searching the ends of the earth for plants that already tolerate high amounts of salt. You come across a dozen different plants, all handling salt but don’t produce enough crop to be used on their own. You analyze all these plants, trying to locate genes that give salt tolerance. You manage to isolate a gene group from a type of sagebrush from Madagascar.
You then carefully remove its DNA and slice the gene group you want from the rest and then insert it into bacteria. These bacteria are then put in with a group of corn cells that the bacteria infest and transfer the desired gene into the A188 corn cells.
The cells are then put under controlled temperature and dosed with certain chemicals to make them form into a normal corn plant. After this the screening process begins to see if the gene was transferred properly.
You now have an A188 inbred to use for breeding. You have also spent countless hours documenting you procedures and proving that the new line is safe in the environment. After two years the government allows you to use the line as it clears all the hurdles and departments it needs for approval.
A188 is a line that has no value except that genes can be added to it so your next step is to take the line and make new lines from it crossed with better lines. You cross A188 with another line and take the offspring from that marriage and cross it again and again to the same good line. What this does is each cross increases the amount of genetic material provided by the good line and reduces the amount of A188. The ideal situation is all of the good line with just the desired gene from the A188. After every cross you must determine if the gene is still present.
When you finally have a good line with salt tolerance you now can start crossing this line with others to create salt tolerant hybrids. You start selling your salt tolerant corn and find that Europe and Japan will not take the crop produced on from salt tolerant corn. You spend time and money trying to get this changed.
So how long did this process take? You were lucky it only took 12 years from start to finish. You also didn't have any major pitfalls, You could find a plant with salt tolerance, find the gene and move it to corn. The good news is that now your sitting on a gold mine, with thousands of acres now able to support corn where it was impossible to grow before.
In the past the products that have been genetically modified came slow out of the gate. They have lacked yield punch for two reasons; the lines they were put on are old by the time the breeding work is done and often carry remnants of poor lines that were used in the gene transfer such as A188. These gene-altered lines do catch up; you're seeing that with Roundup Ready soybeans right now.
Now days it seems that most new genetically modified plants come without taking a yield hit. Breeders are getting better at putting the genes earlier into new line development and thus having more competitive lines to work with. Genetic fingerprinting has also sped the refining process considerably.