Effects of the cultivation of genetically modified Bt crops on nontarget soil organisms - Microbial Ecology in Sustainable Agroecosystems - page 156

tumefaciens , electroporation, or microprojectile bombardment to insert the foreign DNA
physically into the host cell); screening for successful transformants; and then regenera-
tion of the whole transformed plants. The individual transformation events are indicated
in the nomenclature of the GM plant, for example, Bt corn Event 11 (often abbreviated to
Bt 11 or Event Bt 11). The nontransgenic parental cultivar from which the transgenic line
was engineered is called the nontransgenic isoline. The isoline is a plant line that is nearly
genetically identical to its parental base hybrid except for the genetic insertion(s) (e.g., Bt 11
and its nontransgenic parental isoline Providence).
Although it is usually clear through selective screening which plant cells have taken
up the foreign genes, it is seldom known exactly where in the host plant genome new
DNA has been incorporated. Consequently, unintended pleiotropic effects as a result of
the genetic insertion can occur (e.g., Sheveleva et al., 1998; reviewed in Wang et al., 2003,
and in Giovannetti et al., 2005), and whole transgenic plants must be carefully evaluated
for plant performance and undesirable phenotypic characteristics before advancing to the
GM crop registration stage (see the next section on how Bt and other GM plants are regu-
lated in the United States). While obviously abnormal phenotypes are eliminated during
this screening process, it is possible that certain types of pleiotropic effects, such as those
that influence the physiology (e.g., sugar allocation, enzyme activity in roots, lignin con-
tent) of individual insertion events, may not be detected in some plant lines.
8.2.2 How Bt and other GM plants are regulated in the United States
The United States of America is the world's largest producer of GM crops, with 66.8 million
hectares cultivated with GM crops in 2010, more than twice the biotech cultivation area
of any other country ( Table 8.1 ). The U.S. government oversees the development, deploy-
ment, and safety of transgenic organisms through three separate agencies: the USDA
Animal and Plant Health Inspection Service (USDA-APHIS), the EPA, and the Food and
Drug Administration (FDA). Together, these government agencies review potential areas
of concern regarding the introduction of new GM crops, including the potential for gene
flow, resistance management, effects on nontarget organisms and the environment, and
the introduction or elevation of potential allergens. The specific regulatory duties of each
agency are as follows:
1. The USDA is responsible for regulating the introduction (importation, interstate
transport, and field release) of GM organisms (plants, insects, microbes, etc.) or
any other organism that is, or could be, a plant pest. The Biotechnology Regulatory
Service (BRS) of APHIS is the regulatory body within the USDA responsible for
deciding whether a genetically engineered organism is as safe for the environment
as its traditionally bred counterpart.
2. The EPA regulates and assesses the environmental impact of certain types of GM
organisms with pesticidal properties (e.g., insect resistance, disease resistance, and
certain plant growth regulator-expressing products) through the Federal Insecticide,
Fungicide, Rodenticide Act (FIFRA). The EPA regulates the gene and its product,
not the plant (as does APHIS and FDA), as plant-incorporated protectants (PIPs).
Biotechnology companies submit their data to the EPA for permitting and approval
before these crops can be grown commercially. The data requirements for EPA
approval include product characterization, mammalian toxicity, allergenicity poten-
tial, effects on nontarget organisms, and environmental fate, and for Bt products
include insect resistance management strategies (EPA, 2010). EPA also sets tolerances