Genetic Resources in Agroecosystems - Agroecology: The Ecology of Sustainable Food Systems - page 191

TABLE 14.1
Traits of Transgenically Modified Crops

Desired Trait Claimed Benefits Examples

Disease resistance Higher yield due to reduced

crop loss

Inserting an artificial bacterial chromosome into strains of potato
to confer resistance to late blight

Pest resistance Lower pesticide use; higher yield

due to reduced crop loss

Introducing toxin-producing genes from the bacterium Bacillus
thuringiensis into cotton

Improved food quality Less malnutrition in developing

countries

Engineering the Vitamin-A production pathway in rice
(“golden rice”)

Tolerance for abiotic stresses
(e.g., drought, salinity)

Higher food yield on marginal
land; less irrigation

Introducing genes allowing biosynthesis of citric acid in sugar
beets, to increase tolerance of aluminum and uptake of
phosphorus in acidic soil

Herbicide resistance Higher yield due to reduced

weed competition when
crop treated with herbicide

Roundup Ready® soybeans, engineered to resist the herbicide
glyphosate (farmers buy the GE seed and the herbicide from
Monsanto)

Production of a particular
useful compound

Lower product cost Plant-made pharmaceuticals, such as a drug for the treatment of

cystic fibrosis produced by GE corn

• Unintended and hidden effects on the expres-

sion of the genome . Although geneticists can
insert specific genes and create GE organisms
that express desired traits, they have little
control over the unpredictable interaction of
inserted genes with the organism's own genes.
A GE organism could, for example, exhibit
resistance to a particular fungal disease but have
a hidden vulnerability to a bacterial disease.

addition to the targeted pests. Herbicide-resis-
tant GE crops, used in concert with herbicides,
can also have a negative effect on beneficials
and wildlife species by reducing the number of
weeds on which the species depend for food
and cover.

• Consolidation of agribusiness control of genetic

resources. GE organisms are protected by pat-
ents and intellectual property laws. Their
increased use reduces agrobiodiversity, makes
farmers more dependent on off-farm inputs, and
perpetuates the economic divide between devel-
oped and developing countries.

• Accelerated evolution of pesticide-resistant

pests . When a pest species is confronted with
an environment consisting entirely of a crop
producing a specific deterrence compound,
natural selection will favor the evolution of
resistance to that compound.

In addition to all these problems, a broader objection
to transgenic engineering of crop plants (and livestock) is
that it has all the pitfalls — potentially magnified — of
other modern plant breeding techniques. These are dis-
cussed below.

• Creation of “super weeds.” It may be possible

for pest-resistance, herbicide-resistance, or
improved-vigor genes to move from a GE crop
species to a closely related noncrop species or
variety, creating weeds even more resistant to
human attempts to control them, or capable of
disrupting natural ecosystems.

TRENDS IN THE USE OF GENETIC
RESOURCES IN AGRICULTURE

• Introduction of toxic agents and allergens into

the food supplies . The compounds produced by
genes imported into GE organisms may harm
human consumers, in addition to deterring
pests. Even if the genes are incorporated into
varieties only meant for animal feed, they may
find their way into the human food supply.

Large-scale conventional agriculture, aided by advances
in our knowledge of genetics, has marshaled the genetic
resources of domesticated organisms to help create the
dramatic yield increases of the twentieth century. But
because the creation and deployment of new agricultural
varieties and breeds has been directed primarily toward
the goal of increasing the profits of agribusiness conglom-
erates, conventional agriculture has also threatened the
foundation of the food system by tending to centralize
the control over genetic resources, promote genetic
uniformity, and narrow the diversity pool of our crop and
livestock species. These trends undermine agriculture's

• Genetic pollution of the environment . Genes

from GE crops may jump to related native
species, with unpredictable consequences for
natural ecosystems.

• Harm to wildlife and beneficial species. Tox ins

produced by GE crops may kill beneficial
insects, pollinators, birds, and other animals, in