What are the main traits that have been given to GM crops?
The main reason to genetically modify a crop is to add a new trait (characteristic) to a plant in order to improve it in some way.
- Herbicide tolerance - This allows the farmer to spray the crop with a specific herbicide (weedkiller). The crop remains unharmed, while the surrounding weeds are killed.
- Insect resistance - The crop is engineered so that it has a inbuilt insecticide. It produces a substance such as the Bt toxin from the bacterium Bacillus thuringiensis within its cells.
- Disease resistance - Crops can be affected by many different diseases. Attempts to make plants resistant to diseases have included:
- transferring genetic material from viruses that act to "vaccinate" the plant against the original virus.
- adding the trait to produce anti-microbial proteins, so that the the crop has its own inbuilt antibiotic.
- Altered starch composition - Starch from maize, wheat and potato usually has to be chemically altered to make it suitable for the next stage in manufacturing. GM plants that produce starches that already have the right chemical composition will save money.
- Altered oil composition - Similarly plants can be altered to produce oils that more closely match the needs of manufacturers eg. in soaps, cosmetics and margarine.