All living organisms have genetic material. genetic material may be DNA or RNA( e.g in some viruses) depending upon the organism. However, Most prominent genetic material in living organisms is DNA.When scientists alter genetic material, or DNA, it’s called genetic modification (GM).Genetically modified crops are plants, whose DNA has been modified using genetic engineering techniques, to resist pests and agents causing harm to plants and to improve the growth of these plants to assist in farmers efficiency.
Techniques of genetic modification
The Genetic Modification techniques which are currently being used to transfer foreign genetic material into animals and plants include:
* Bacterial carriers
* Gene silencing
* Gene splicing
What are Bacterial Carriers ?
The bacterium Agrobacterium can infect plants, which makes it a suitable carrier for delivering DNA to a new organism.
The selected gene which is intended to be inserted into a plant, is first fused with the extrachromosomal DNA called plasmid. Thereafter plant is exposed to the bacterium as a result of which the desired DNA gets integrated with the plant chromosome.
What is Electoporation ?
The prepared target cells (plant cells)are immersed in a special solution with the DNA intended to be inserted in the plant genome. A short but intense electric shock is then passed through the solution. This results in small pores in the cell walls, which allow the entry of new genetic material the nuclei.
The damaged cells are placed into another solution and are allowed to repair their fractured cell walls, locking the ‘donor’ DNA inside the cell. The selected DNA is incorporated as a plasmid into the host bacterium, which is then incorporated into the plant DNA to provide the host with a new gene.
What is Gene silencing ?
This technique is used to eliminate an unwanted characteristic from an organism. The gene responsible for the organism’s undesirable trait is identified and is ‘switched off’ i.e is not allowed to express itself. This technique is used to prevent plants like peanuts and wheat from producing the proteins (allergens) that cause allergies in human beings. Another approach is to insert foreign DNA within a gene to inactivate it.
What is Gene splicing ?
The concept of gene splicing involves cutting a gene from one organism and inserting it into the DNA of another organism so that the desired characteristic can be transferred from one organism to another. Bacteria contain restriction enzymes that attack the foreign DNA by cutting it into precise sections and preventing it from being inserted into the bacterium’s chromosome.These restriction enzymes are used to cut the desired DNA from one organism and then is inserted into the other organism cellular DNA.
What is Microinjection ?
The desired DNA is injected into a fertilized ovum (female egg cell) through an extremely slender device called a glass capillary tube. The genetically modified egg is then transplanted into the prepared uterus of a receptive female and allowed to grow.
This method ensures that almost every cell in the developing organism’s body contains the new DNA.
What are the types of GM Crops ?
Pesticide resistant plants
Scientists have transferred a gene to the plants which enables the plant to resist a certain pesticide. When the farmer sprays his genetically modified crop with pesticides, he or she can destroy most of the pests without killing the plants.
Insecticide Resistant Plants
Scientists have genetically modified sweet corn so that it produces a poison which kills harmful insects. This means the farmer no longer needs to fight insects with insecticides.The genetically modified corn is called Bt-corn, because the insect-killing gene in the plant comes from the bacteria bacillus thuringiensis
Vitamin Rich Rice
Golden rice is genetically modified rice that now contains a large amount of A-vitamins. The rice contains the element beta – carotene which is converted in the body into Vitamin- A. So when you eat golden rice, you get more vitamin A.
Long Shelf Life
Long-lasting, genetically modified tomatoes came on to the market in 1994 and were the first genetically modified food available to consumers. The genetically modified tomato produces less of the substance that causes tomatoes to rot, so remains fresh for a longer period of time.
Advantages of Genetically Modified Crops
* Crops are more productive and have a larger yield.
* Offer more nutritional value and better flavor.
* A possibility that they could eliminate allergy-causing properties in some foods.
* Inbuilt resistance to pests, weeds and disease.
* More capable of thriving in regions with poor soil or adverse climates.
* More environment friendly as they require less herbicides and pesticides.
* Foods are more resistant and stay ripe for longer so they can be shipped long distances or kept on shop shelves for longer periods.
* As more GMO crops can be grown on relatively small parcels of land, they are an answer to feeding growing world populations.
Dangers of Genetically Modified Crops
* Herbicide-resistant and pesticide-resistant crops could give rise to super-weeds and super-pests that would need newer, stronger chemicals to destroy them.
* GMO crops cross-pollinate with nearby non-GMO plants and could create ecological problems.
* Harm to other organisms. For example genes and their effect included in a crop may turn out to be poisonous to insects (monarch butterfly poisoned by GMO corns).
* Major trading countries that obtain most of the benefit from the production and trade of genetically modified crops. This might cause more geopolitical conflicts.