The practice of combining different varieties of the same plant to produce more desirable hybrids dates to the beginning of human civilization; the selective breeding of plants through cross pollination is how domestic vegetables were produced from wild varieties. Scientists use genetic engineering techniques to modify vegetables by inserting or deleting genes in plant DNA. Many people resist genetic modification, asserting that the practice poses dangers to agriculture and consumers.
Through his study of the inherited characteristics of pea plants, Gregor Mendel (1822-1884) pioneered the science of plant genetics. In 1908 botanist George H. Shull demonstrated heterosis, the tendency of crossed species to outperform their parents. Eventually scientists were able to form hybrids from distantly related species and species that do not ordinarily reproduce sexually with one another. Experienced gardeners can produce hybrid vegetables through cross pollination.
Genetically Modified Vegetables
In nature, external genes that penetrate plant cells can cause changes in DNA. Genetic engineers use a “gene gun” to fire genes into a plant; they also insert genes with a tiny syringe and attach them to a virus that penetrates plans. The first genetically engineered vegetable sold commercially was a tomato that ripened without getting soft. Scientists are now engineering vegetables yield seedless varieties, to resist certain diseases and insects and to ship and store better. A laboratory is ordinarily needed to genetically engineer vegetables.
The science of genetically modified (GM) plants is still evolving; the possibilities for future genetically modified vegetables is wide ranging. One advantage to GM plants is that growers do not have to use toxic chemical pesticides on vegetables engineered to withstand insect damage. It is expensive to remove weeds by hand or with machines; vegetables can be engineered to resist herbicides that kill weeds, making them cheaper to grow. Botanists are working to create vegetables that resist disease-bearing bacteria, fungi and viruses. A gene from cold-water fish added to potato plants has helped seedlings withstand freezing temperatures. Plant scientists are working on creating vegetables that can withstand drought or soil with high salt content. Rice has been genetically modified to contain more beta-carotene (vitamin A). Researchers are working to engineer edible vaccines in potatoes and tomatoes. Vegetables are being modified to ship better and store longer.
Debate continues as to whether or not pollen from corn genetically modified with an insect-killing bacterium kills monarch butterflies. Some fear that insects will become resistant to pesticides added genetically to crops, making those crops vulnerable in the future. Critics assert that genes from plants engineered to tolerate herbicides may jump to weeds through cross pollination, creating super-weeds, or that genes from genetically modified plants may jump to unmodified plants. Some fear that unknown disease could strike a genetically modified crop that dominates the market; there is protection in the diversity of unmodified plants.
Ethical and Health Concerns
Critics of GM crops assert that it is a violation of nature to mix genes among species, to add plant genes to animals and animal genes to plants. Some fear that companies that own patents to genetically modified plants will dominate markets to the detriment of the developing world.
Deborah P. Whitman, senior biotechnology editor for Proquest, an information company, says that, on the whole, scientists do not believe there is a risk to human health from eating genetically modified food. The exception is the unproven possibility of the appearance of unanticipated allergens.