Agriculture – Part 3: Bio Engineering of Plants

Humanity has engineered plants and animals since the dawn of the Neolithic Revolution, selecting seeds from the best plants, and cross-pollination to create new plant and animal varieties. Humans used observation and experimentation to achieve improved crop yields and better livestock. Charles Darwin and Gregor Mendel provided the foundational science behind what we know of today as genetics and bioengineering. Through Darwin we discovered how the natural processes of selection are influenced by environmental factors. Through Mendel we learned how inherited characteristics are passed down through human selection. Their scientific work comprised of observation and detailed record keeping.

Charles Darwin on the left, a failed teacher, and Gregor Mendel on the right, a priest, worked largely on their own in discovering the science behind natural and human-derived selection.

In 1859 Darwin published “The Origin of the Species.” Between 1856 and 1863 Mendel studied pea plants and made two discoveries which he called the Law of Segregation and the Law of Independent Assortment, the fundamentals of how inherited traits get passed along. When Mendel was promoted to abbott in 1868 he ended his experiments. Neither man knew of each other. Interestingly in 1869 another scientist, Friedrich Miescher identified something he called the nuclein inside human white blood cells. Miescher had found DNA. But it was 84 years later that James Watson and Francis Crick discovered the unique characteristics of the DNA molecule.

DNA Allows Us to Bio Engineer Living Things

DNA is  found in every chromosome in the nucleus of almost every cell in our bodies (red blood cells have no nucleus so they are the exception) as well as in all the cells in plants and animals on this planet. Every strand of DNA contains genes and it is genes that determine  inherited traits. Sexual reproduction combines the DNA of two parents in the offspring. When egg and sperm meet each represents half of the genetic content of each parent. This means that not all characteristics of a parent get expressed in an offspring. When Mendel studied his pea plants he uncovered how traits could be transmitted from generation to generation, some traits dominant and some recessive. Mendel didn’t know about genes when he was recording his observations. But he had discovered the mechanism of genetic manipulation. Today agricultural science manipulates genes in living things, not only intraspecies but interspecies.

Why Do We Want to Modify Agricultural Products Using Genetics?

On Monsanto’s website, a company that is heavily invested in genetically engineered crops, herbicides and pesticides, it describes our human dilemma caused by population growth. Monsanto is seen by environmentalists as a pariah because its genetically modified crop solutions help bolster the sales of its own herbicide and pesticide products. But nonetheless Monsanto is not wrong in stating the facts that by 2050 the planet will have a human population exceeding nine billion. That more than nine billion represents a 30% increase over our present human population, a number equivalent to adding a today’s China and India to the planet. What that means is we simply need to produce much more through agriculture to meet food demands. In Monsanto’s words “farmers must produce more in the next few decades than they have in the past 10,000 years combined.”

Genetic Engineering in Modern Agriculture

Genetic engineering is playing a significant role in worldwide agricultural production today. What proportion of  foods today are genetically manipulated?

  • 60 to 70% of processed foods in U.S. grocery stores contain oils or ingredients derived from biotech corn and soybeans
  • 45% of all corn grown in the U.S. is genetically engineered
  • 85%  of soybeans in the U.S. are genetically altered

For farmers the attractions are obvious.  Genetically engineered crops produce higher crop yields and cost far less to maintain.

A brief discussion on some of the most commonly grown genetically modified crops follows:

Tomatoes

In attempting to stop tomatoes from rotting the Flavr Savr  was invented in 1994. It was the first genetically engineered food crop to receive human consumption approval. A tomato enzyme polygalacturonase, PG for short, was identified as having the ability to contribute to the ripening of tomatoes. Researchers at Calgene, Inc., introduced an altered antisense gene to reduce the formation of PG. The benefit to farmers was immediate. Tomatoes with the antisense gene could be left to ripen longer in the field. Rather than being treated chemically to ripen, Flavr Savr tomatoes could naturally mature enhancing the flavour of the end product.

Extensive testing by the U.S. Food and Drug Administration determined that these altered tomatoes posed no harm to humans. But what was an agricultural success in genetic engineering turned into a commercial failure when the product was introduced and labelled as genetically engineered. Today genetically engineered products are not so blatant in their labelling.

Corn

Corn of all plants cultivated in North America seems to be most associated with genetic engineering. Corn was domesticated in North America very early in the Neolithic Revolution. It has been engineered from its ancestral form, teosinte, a grass, into modern corn varieties. Farmers cross-bred various strains of primitive corn to improve yields and cultivate desirable traits. This manipulation of corn was intraspecies.

The genetic modification being made by agribusiness research companies today are more interspecies than intraspecies. Corn is no exception.

A protein toxic to caterpillars found in a strain of bacteria called Bacillus Thuringiensis (Bt) has been bioengineered into corn plants. The gene allows the corn to express the toxin and kill the caterpillars that feed on its leaves and cobs. But it has become an arms race between genetic engineers and the insect pests. By planting  too much bioengineered product farmers are speeding up evolutionary resistance to the toxin by new generations of caterpillars and ultimately crop yields have been affected.

Companies like Monsanto have invested heavily in developing new types of corn engineered to tolerate herbicides such as Roundup(TM), a popular weed killer used on home gardens and lawns. Monsanto is the inventor of Roundup. So developing Roundup-ready crops that contain genes tolerant to glyphosate, a chemical toxic to weeds, means crops can be sprayed and only the weeds die. But some weeds over time develop resistance to herbicides and these survivors pass along inherited traits. You see, Darwin was right.

Soybeans

Corn isn’t the most genetically manipulated crop grown globally. That honour goes to soybeans. Genetically modified soybeans containing resistance to herbicides like Roundup were first planted in the United States in 1996. By 2006 genetically modified soybean plantings extended to 9 countries.

In countries like Argentina almost 100% of the soybean crop is genetically modified. The United States is a close second. Today 58.6% of worldwide soybean production comes from genetically modified crops.

We ingest food additives laced with genetically modified soybeans. Our domestic farm-bred animals are raised on soybean-derived feeds.

When Monsanto developed Roundup-Ready(TM) soybeans the goal was to create plants that could be dosed with a less toxic herbicide than atrazine. Atrazine was a commonly used herbicide before Roundup. Atrazine had long-term environmental consequences where Roundup was perceived to have a shorter impact in the environment. But glyphosate, the active chemical in Roundup has proven to be highly toxic to many plants, and to aquatic life when it enters lakes and streams through agricultural runoff.

In some areas where Roundup-Ready soybeans are grown, nearby plants have begun to exhibit glyphosate resistance. When these plants are weeds the benefit of the herbicide is diminished impacting crop yields. As more weeds become Roundup resistant, new genetically modified soybean variants will need to be developed to counter this escalating arms race. New herbicide treatment plans will potentially introduce more herbicide residue into the larger environment.

New methods of tillage, crop rotation, growing of cover crops, and other biointensive techniques including weed tolerance may prove to be far more effective tools for maintaining quality and crop yield.

Rice

Rice provides basic nutrition to much of South and East Asia. Golden Rice, developed in 1999, contains two turned-off and two inserted genes that cause beta-carotene to accumulate in the rice grains. The golden colour indicates the concentration of Vitamin A to meet the recommended daily dosage in 100 to 200 grams of rice. Golden Rice is contributing  to reductions in diseases related to Vitamin A deficiency. Vitamin A Deficiency (VAD) causes blindness in 250,000 to 500,000 children annually. The blindness is an indicator of a more serious problem that leads to half of these  children dying within a year of becoming blind. That’s because VAD impacts a child’s immune system putting them at increased risk to common infections.

Cabbage, Broccoli, Sprouts and Cauliflower

Even members of the cabbage family have been targets for genetic modification. The insertion of a Bacillus Thuringiensis (Bt) genes in cabbage, broccoli and cauliflower was introduced as a toxin to kill Cabbage Butterfly larvae. Increasing resistance on the part of the butterfly population eventually led to a decline in Bt-cabbage. More recently a gene responsible for the poison in scorpion tails has been inserted into cabbage plants. The poison expressing genes are modified to not harm humans.

Using Genetic Engineering to Turn Plants into Medicine

Hepatitis B and cholera are among a number of diseases that may be treated by making humans eat fruit or vegetables that are genetically modified to produce vaccines.  Researchers are engineering bananas, potatoes, lettuce, carrots and even tobacco to produce a way to vaccinate people without a needle.

Bananas are particularly useful. An altered form of  the disease virus is injected into banana saplings. The altered virus genetic information is reproduced in the plant and fruit. When consumed by humans the bananas help build immunity to fight these diseases.


Len Rosen lives in Toronto, Ontario, Canada. He is a researcher and writer who has a fascination with science and technology. He is married with a daughter who works in radio, and a miniature red poodle who is his daily companion on walks of discovery. More...

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  • The World Trade Organization has made a preliminary ruling that European Union restrictions on genetically engineered crops violate international trade rules. The United States, Canada, and Argentina together grow 80 percent of all biotech crops sold commercially, by which the EU regulates such crops. The countries argued that the EU’s regulatory process was far too slow and its standards were unreasonable given that the overwhelming body of scientific evidence finds the crops safe.

    • Hi Ella, I think there are three big challenges bio-engineered crops face:
      1. Addressing the intra-species potential to introduce an unintended genetic variable that remains hidden before expressing itself in later generations of crops.
      2. Defining what is the right duration for testing the output of genetic engineering to assure the public of the safety of the product.
      3. Educating the public about the science of bio-engineering so that consumers understand how this compares to “natural” or “human” selection in the process of improving crops for human and domestic animal consumption.