Genetically altered bacteria and viruses are also used in agriculture. Originally, genetic engineering techniques worked well only with animal cells, because plants have tough cell walls that most bacteria can not get through. And those that can are usually harmful. But scientists found a way to take a harmful bacterium called Agrobacterium tumifaciens, which normally causes crown gall disease, and make it beneficial. The bacterium infects a plant by inserting its DNA into the plant cell, which causes a tumor to grow. But when the disease-causing gene is snipped out of the bacterium's plasmid, the bacterium is rendered harmless and becomes the perfect vector.
Viruses can also be used to modify plant genes. One such virus comes from the well-studied mosaic virus family, namely the cauliflower mosaic virus. It can be rendered harmless and fitted with genetic information that makes a plant more tolerant to herbicide or more insect resistant.
Genetically engineered foods are already on the market. Scientists have developed tomatoes that keep their fresh taste longer, peas that retain their sweetness, and strains of corn and wheat that are pest resistant. Some genetically modified potatoes contain 60 percent more starch. The extra starch decreases the amount of cooking oil that soaks into the potatoes, solving the problem of oily potato chips or greasy french fries. But more colorful tomatoes or greaseless chips are not the only reasons for this growing field of science.
Some scientists believe that genetically modified foods may be an important tool for feeding the world in the future. Researchers predict that we will need to increase global food production by 50 percent within the next fifty years in order to keep up with the population growth. That is a tall order to fill. So genetic engineers
are looking at ways to increase production; for example, developing plants that produce more food than they normally would or are able to fight off diseases that would otherwise diminish their yield.
But other scientists argue that genetically modified foods and plants are a cause for concern. They debate the safety and long-term effect that consuming modified foods will have on a person's health and the possible consequences of releasing genetically engineered recombinations into the environment. Mutations that may occur naturally within a plant will still occur within genetically modified cells. There is also the potential for naturally occurring viruses to recombine with the genetically altered viral DNA inserted into the plant. Could this cause a more virulent infection sometime in the future? As the debate continues, more than half of all food for sale in North America contains some form of genetically modified ingredients.
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