12.1.4: Biotechnology in Agriculture

Biotechnology is a general term, meaning the use of technology to study or solve problems of living organisms. But the term is commonly used (as it is here) to mean genetic engineering, the altering of an organism’s genes (its DNA), resulting in what the popular press terms a genetically modified organism (GMO). The term now includes genome editing, the precise alteration of DNA using tools such as CRISPR-Cas.¹⁰

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“Genetic engineering” or “genetically modified organism” sounds ominous—like something that might concern us.

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As applied in agriculture, biotechnology is used to create desired genetic characteristics in plants. Ordinarily, these goals have been (and still are) done by crossbreeding—to get more nutritious vegetables, more drought-resistant plants, apples that don’t brown, roses with fewer thorns, etc.

In many cases, biotechnology is simply used as a faster and a more direct and precise method of crossbreeding. (Crossbreeding has sometimes taken decades and thousands of pain-staking crosses to get a desired genetic change in a plant.) A desirable gene can be selectively transferred into a plant, or an undesirable gene can be inactivated.

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One scientist tried to use crossbreeding to combine the leaf of a cabbage with the root of a radish to get an entirely edible plant. Alas, what resulted was the leaf of the radish with the root of the cabbage.

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Agricultural biotechnology has the potential to make a tremendous impact on the health of many people, especially in countries where food is scarce and the nutritional quality of the staple diet is inadequate. Often, the scarcity isn’t due to inadequate food production, but is the result of losses in the food supply system.

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Year after year of drought causes extensive crop losses, resulting in economic losses to the farmer, and the consumer who pays higher food prices.

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There are tremendous losses—particularly in developing countries—from infestation of crops by pests, harsh weather, and deterioration of the harvest during transport or storage. Biotechnology holds dramatic promise for such problems—to obtain plants that are more nutritious, need less fertilizer, and have increased resistance to viral infection, pests, deterioration, etc.

The achievement of a tastier tomato by genetic alteration pales by comparison. However, in 1989, Calgene, Inc. received a patent for a tomato (dubbed Flavr Savr), in which the enzyme that causes it to deteriorate rapidly was inactivated by genetic engineering (see Fig. 20-3). Without this enzyme, the tomato lasts longer after picking and thus can be picked when ripe and tasty rather than when green with flavor compounds not yet activated. Campbell Soup Company helped finance its development. But in response to public fear of scary-sounding genetically modified food, they announced that they wouldn’t use it in their products; however it was used for a time in tomato sauce in the U.K.

A tastier vine-ripened tomato can make for a more nutritious diet. Presumably, people eat more tomatoes when they are tastier.

In 2015, the Innate™ potato passed muster as being as safe and nutritious as regular potatoes. It’s Innate in that the inserted genes come from other varieties of potatoes. The potato is genetically modified to produce less acrylamide (a carcinogen in rodents and possibly in humans) when deep-fried and to prevent black spots from forming when raw potatoes are bruised (lots of potatoes are discarded because of bruising). A second-generation Innate potato was engineered to be resistant to potato blight, which caused the Irish potato famine. In response to anti-GMO voices, McDonald’s announced it will not use these potato varieties.

Figure 20-3: The decay gene is inactivated in the Flavr Savr tomato

With biotechnology, genes can be transferred across a wider range of plant species than by crossbreeding. One plant might, for example, make a protein that provides resistance to the formation of damaging ice crystals in freezing weather. The gene for this protein might then be transferred to other plants, making them resistant to frost damage.

One thing that crossbreeding can’t do, but biotechnology can, is transfer non-plant genes into a plant. One such gene is for a protein found in the coat of a virus that infects and damages crops. (In nature, some plant viruses transfer their genes into a plant’s DNA as part of their normal disease-causing process.)

It’s been known for some time that crops infected with a mild strain of some viruses aren’t as susceptible to infection by more damaging strains (similar to the way infection with the cowpox virus protected people against smallpox in the days before vaccines). In investigating this phenomenon, scientists found that one of the virus’s proteins, alone, could confer the same protection. Plants, in this way, can be “vaccinated” against a viral infection.

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Just the protein part of a virus is used in some human vaccines—the protein doesn’t cause the disease when injected, nor is it infective. But it causes us to make the antibodies that protect against the virus.

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Using biotechnology, the gene that provides the directions to make the desired protein can be removed from the virus and inserted into a plant’s DNA. This genetically altered plant then makes this “foreign protein” for its own protection against disease. This method has been used, for example, to create rice varieties that resist infection by a virus that causes the loss of millions of dollars worth of rice crops in countries worldwide.⁴

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When we eat the “foreign protein,” it is digested quickly into its component amino acids. The digestive tract doesn’t see it any differently than other proteins in the plant. After all, a plant’s native protein is “foreign” to us as well.

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Biotechnology might also be used to transplant a set of genes that, for example, gives an organism the ability to convert nitrogen gas into ammonia. As discussed earlier, the nitrogen-fixing bacteria that reside in the roots of legumes can convert nitrogen gas into ammonia for use by the plant (plants can use ammonia—but not nitrogen gas— to make protein). If these bacterial genes could be transferred into plants that aren’t infected by these nitrogen-fixing bacteria, they wouldn’t need nitrogen-containing fertilizer—the plants would make their own.

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Using abundant natural resources—nitrogen from the air and energy from the sun—to make fertilizer “on site” is an attractive alternative to industrial production which, as said earlier, requires energy and technology, limiting its use in developing countries.

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The FDA treats bioengineered food as it does any other food. The Flavr Savr tomato, for example, had its “decay gene” inactivated by biotechnology, whereas the DiVine Ripe tomato had its “decay gene” activity bred out. As another example, a plant can be made to produce its own fungicide by the bioengineered introduction of an antifungal gene. There are many other crop plants that naturally have the genes to produce such agents in even larger amounts (naturally disease-resistant varieties).