Disease Resistant Crops

Genetically Modified Foods: Diesease resistant crops- Mechanism

When a farmer grows a crop variety that is resistant to certain disease-causing pathogens, the invader is quickly recognised by the plant and specific defences are activated. These defences stop the pathogen in its tracks and no disease develops. If the crop variety is not resistant, but is susceptible to those pathogens, the invading pathogen manages to avoid recognition by the plant. The pathogen can then infect the plant, colonise it, and cause disease. The susceptible plant has all of the defences it needs to deal with invading pathogens, but because it fails to recognise the invader, the defences are not activated. However, it is possible to by-pass the recognition process and to directly activate the defences. This is known as induced resistance and it can be triggered in plants using compounds known as elicitors. These elicitors can work in two ways, they can activate defences directly, or they can activate defences only following pathogen attack. The latter is called priming and is potentially very useful, since it leads to the deployment of defences only when there is real danger.

There are many viruses, fungi and bacteria that cause plant diseases. Plant biologists are working to create plants with genetically-engineered resistance to these diseases.

Herbicide Tolerant Crops

Herbicides sprayed on Herbicide tolerant GM Crops

Above shows herbicides being sprayed on herbicide tolerant crops

For some crops, it is not cost-effective to remove weeds by physical means such as tilling, so farmers will often spray large quantities of different herbicides (weed-killer) to destroy weeds, a time-consuming and expensive process, that requires care so that the herbicide doesn’t harm the crop plant or the environment. Crop plants genetically-engineered to be resistant to one very powerful herbicide could help prevent environmental damage by reducing the amount of herbicides needed. For example, Monsanto has created a strain of soybeans genetically modified to be not affected by their herbicide product Roundup. A farmer grows these soybeans which then only require one application of weed-killer instead of multiple applications, reducing production cost and limiting the dangers of agricultural waste run-off.

Pest Resistant Crops

Genetically Modified food: Pest resistance (Corn)

Corn- a type of pest resistant crop

Crop losses from the destruction of insect pests can be staggering, resulting in major financial losses for farmers and a lack of food in developing countries. Farmers usually use tons of chemical pesticides annually. Consumers do enjoy eating food that has been treated with pesticides because of potential health hazards, and run-off of agricultural wastes from the excessive use of pesticides and fertilizers can potentially poison the water supply and cause harm to the environment. Growing GM foods such as B.t. corn can help reduce the application of chemical pesticides and reduce the cost of bringing a crop to market.

What are Genetically Modified Foods?

The term GM food or GMOs (genetically-modified organisms) is commonly used to refer to crop plants modified for human or animal consumption using cutting edge molecular biology techniques. Plants have been modified in the laboratory to enhance wanted traits like increased resistance to herbicides or better nutritional content. Breeding has traditionally carried out the enhancement of desired traits, but usual plant breeding methods can be very time consuming and are not very accurate. Genetic engineering, on the other hand, is able to produce plants with an exact desired trait very quickly and with great accuracy. For example, plant geneticists have the capability to isolate a gene responsible for drought tolerance and insert that gene into a different plant. This new genetically-modified plant will gain drought tolerance as well. With genetic engineering, not only can genes be transferred from one plant to another, but genes from other organisms also can be transferred. An example of this is the use of Bacillus thuringiensis genes in corn and other crops. The Bacillus thuringiensis, is a naturally occurring bacterium that is able to produce crystal proteins that are lethal to insect larvae. The B.t. crystal protein genes have been able to be transferred into corn, enabling the corn to produce its own pesticides against some insects such as the European corn borer.

Genetically Modified Animals

Genetically engineered animals are a powerful method of introducing wanted traits into animals by recombinant DNA technology by adding, changing or removing certain DNA sequences to change the characteristics of the animal. The process of genetically engineering animals is a slow and tiring process that requires a large amount of funding. Thanks to advanced technologies being introduced, genetically modifying animals is becoming simpler and more precise. This is not only transforming science, but could also transform the food we eat.

The first transgenic (genetically modified animal), was made by injecting DNA into eggs then, implanting the eggs in animals and then waiting months to obeserve if any offspring had incorporated the extra DNA. At first only about 10% performed correctly, in the end causing this a long and costly.

Genetically modified animals currently being developed can be placed into six different broad groups based on the purpose of the genetic modification: (1) to increase production or food quality traits (e.g faster growing fish, pigs that expel less toxins); (2) to improve animal health (disease resistance); (3) to produce products for human theraputic use (e.g pharmacutical products or tissue implantations); (4) to enrich or increase the animals’ interactions with humans (e.g hypo-allergenic pets); (5) to develop animal models for human diseases (e.g pigs used as models for cardiovascular disease); (6) and to make industrial or consumer products (e.g fibres for multiple uses).