Genetic Engineering in Agriculture, Part 2

Genetic engineering in agriculture overcomes some of the limitations of traditional agriculture. Until now, we’ve spent enormous efforts to adapt the environment to the plant. That’s what a farm is, an adapted environment with the purpose of maximizing the growth of a plant. Now, we have the possibility of being able to adapt the plant to fit the environment. Here I will list the limitations of traditional methods that genetic engineering in agriculture overcomes. Also, I’ll list some of the genetically modified plants in widespread use over the world today.

1. Limitation number one: in traditional agriculture they select specific traits (genes) for crosses, but at the same time other hidden genes that are not desirable may also be transferred. Using genetic engineering in agriculture, single genes are transferred.
   
2. Limitation number two: there are many genes in nature that can’t be crosses into crop plants because they are in different species. Using genetic engineering in agriculture, genes from any organism can be transferred.
   
   
3. Limitation number three: traditional agriculture is slow. Genetic engineering is rapid. You can see results in weeks.
   
   
4. Limitation number four: the ecological thrust of agriculture has remained to use genetics and technology to adapt the environment to the plant. With genetic engineering, the plant can be adapted to the environment.
   

Genetically modified plants are in widespread use. I’ll give you three examples.

Plants That Make Their Own Insecticide

Insecticides are chemicals that kill insect pests. The problem with insecticides, however, is that many of them are not specific. They target many insects, not just the pest. In addition, some insecticides are toxic to the environment in other ways. Insect larvae (the immature stage of insects) eat, among other things, bacteria.

There is a bacterium called Bacillus thuringiensis that has a gene that defends itself against insect larvae. This gene codes for a protein that binds to the insect larvae’s intestine, and makes it loose all of its fluids. The insect gets chronic diarrhea and dies.

The gene coding for this toxin protein has now been introduced to corn, cotton, soybeans and tomato cells. These cells were cloned to make plants that express the toxin in the leaf. As a result, the insect caterpillars land on the leaf, begin to eat and die very quickly. The population of this pest goes way down.

This technology has reduced insecticide use by 90%. This is an environment-friendly use of genetic engineering in agriculture.

Plants Resistant to Herbicides

Weeds can be killed by repeated applications of herbicides (chemical that kill weeds). These chemicals, however, very often kill beneficial plants as well, and even some crops. These are non-specific toxins. Great care is needed to use herbicides properly.

Genes had been identified from bacteria and other sources that code for proteins that break down herbicides. That’s how the bacteria survive to them. These genes had been isolated from the bacteria and put into cotton, corn, soybeans, rice, etc. As a result, these modified crops are now resistant to the herbicide. The herbicide can be applied without any risk of damaging the crop. These crops are in widespread use all over the world.

Nutritionally Rich Rice

Rice grains are deficient in their protein, in terms of their amino-acid balance. There is an ongoing effort to improve that. In addition, rice does not make a substance called beta-carotene. People require beta-carotene, which gets converted into vitamin A, in their diet. Rice plants do not have the gene to make beta-carotene. As a result, about 250000 children go partially blind each year. They are eating rice, and they don’t get enough beta-carotene in their diet.

Other organisms have the genes coding for enzymes that can produce beta-carotene through a biochemical pathway. Ingo Potrykus isolated DNA for each one of these enzymes. One of them was from a bacterium, the other genes happened to be from a daffodil plant. One by one, over a period of a decade, he took each one of these genes and introduced them into a rice plant, along with a promoter that would stimulate gene expression in the developing rice grain.

The result is a rice plant that made grains with beta-carotene. These plants are now being crossed with local varieties all over the world to make the beta-carotene phenotype part of rice that is used in different regions of the world.