1). Farmers and plant breeders have relied for centuries
on crossbreeding, hybridization and other genetic
modification techniques to improve the yield and quality
of food and fiber crops and to provide crops with built-in protection against insect pests, disease-causing organisms and harsh environmental conditions. Stone Age farmers selected plants with the best characteristics and saved their seeds for the next year’s crops. By selectively sowing seeds from plants with preferred characteristics, the earliest agriculturists performed genetic modification to convert wild plants into domesticated crops long before the science of genetics was understood.
2). As our knowledge of plant genetics improved, we purposefully crossbred plants with desirable traits (or lacking undesirable characteristics) to produce offspring that combine the best traits of both parents. In today’s world, virtually every crop plant grown commercially for food or fiber is a product of crossbreeding, hybridization or both. Unfortunately, these processes are often costly, time consuming, inefficient and subject to significant practical limitations. For example, producing corn with higher yields or natural resistance to certain insects takes dozens of generations of traditional crossbreeding, if it is possible at all.
3). The tools of biotechnology allow plant breeders to select single genes that produce desired traits and move them from one plant to another. The process is far more precise
and selective than traditional breeding in which thousands of genes of unknown function are moved into our crops. Biotechnology also removes the technical obstacles to moving genetic traits between plants and other organisms.
4). This opens up a world of genetic traits to benefit food production. We can, for example, take a bacterium gene that yields a protein toxic to a disease-causing fungus and transfer it to a plant. The plant then produces the protein and is protected from the disease without the help
of externally applied fungicides.
IMPROVING CROP PRODUCTION
The crop production and protection traits agricultural scientists are incorporating with biotechnology are the same traits they have incorporated through decades of
crossbreeding and other genetic modification techniques: increased yields; resistance to diseases caused by bacteria, fungi and viruses; the ability to withstand harsh environmental
conditions such as freezes and droughts; and resistance to pests such as insects, weeds and nematodes.
Natural Protection for Plants
Just as biotechnology allows us to make better use of the natural therapeutic compounds our bodies produce, it also provides us with more opportunities to partner with
nature in plant agriculture.
Through science, we have discovered that plants, like animals, have built-in defense systems against insects and diseases, and we are searching for environmentally benign chemicals that trigger these natural defense mechanisms so plants can better protect themselves.
Biotechnology will also open up new avenues for working with nature by providing new biopesticides, such as microorganisms and fatty acid compounds, that are toxic
to targeted crop pests but do not harm humans, animals, fish, birds or beneficial insects. Because biopesticides act in unique ways, they can control pest populations that
have developed resistance to conventional pesticides.
A biopesticide farmers (including organic farmers) have used since the 1930s is the microorganism Bacillus thuringiensis, or Bt, which occurs naturally in soil. Several of the proteins the Bt bacterium produces are lethal to certain insects, such as the European corn borer, a prevalent pest that costs the United States $1.2 billion in crop damage each year. Bt bacteria used as a biopesticidal spray can eliminate target insects without relying on
chemically based pesticides. Using the flexibility provided by biotechnology, we can
transplant the genetic information that makes the Bt bacterium lethal to certain insects (but not to humans, animals or other insects) into plants on which that insect feeds. The plant that once was a food source for the insect now kills it, lessening the need to spray crops with chemical pesticides to control infestations.
Increasing Yields
In addition to increasing crop productivity by using built-in protection against diseases, pests, environmental stresses and weeds to minimize losses, scientists use biotechnology
to improve crop yields directly. Researchers at Japan’s National Institute of Agrobiological Resources added maize photosynthesis genes to rice to increase its efficiency at
converting sunlight to plant starch and increased yields by 30 percent. Other scientists are altering plant metabolism by blocking gene action in order to shunt nutrients to
certain plant parts. Yields increase as starch accumulates in potato tubers and not leaves, or as oil-seed crops, such as canola, allocate most fatty acids to the seeds.
Biotechnology also allows scientists to develop crops that are better at accessing the micronutrients they need. Mexican scientists have genetically modified plants to secrete
citric acid, a naturally occurring compound, from their roots. In response to the slight increase in acidity, minerals bound to soil particles, such as calcium, phosphorous and potassium, are released and made available to the plant.
Nitrogen is the critical limiting element for plant growth and, step-by-step, researchers from many scientific disciplines are teasing apart the details of the symbiotic relationship
that allows nitrogen-fixing bacteria to capture atmospheric nitrogen and provide it to the plants that harbor them in root nodules.
- Plant geneticists in Hungary and England have identified the plant gene and protein that enable the plant to
establish a relationship with nitrogen-fixing bacteria in the surrounding soil.
- Microbial geneticists at the University of Queensland have identified the bacterial gene that stimulates root
nodule formation.
- Collaboration among molecular biologists in the European Union, United States and Canada yielded the
complete genome sequence of one of the nitrogen-fixing bacteria species.
- Protein chemists have documented the precise structure of the bacterial enzyme that converts atmospheric
nitrogen into a form the plant can use.
