GMO Myths and Truths

culture process remain a major source of
unintended damaging side-effects.
These newer methods are also cumbersome
and time-consuming, so much so that to date
no GM crop that is currently being considered
by regulators for approval or that is in the
commercialisation pipeline has been produced
using these targeted engineering methods.
1.3.6. Why worry about mutations
caused in genetic engineering?
GM proponents make four basic arguments to
counter concerns about the mutagenic aspects of
genetic engineering:
“Mutations happen all the time in nature”
GM proponents say, “Mutations happen all the
time in nature as a result of various natural
exposures, for example, to ultraviolet light, so
mutations caused by genetic engineering of plants
are not a problem.”
In fact, mutations occur infrequently in
nature. 9 And comparing natural mutations with
those that occur during the GM transformation
process is like comparing apples and oranges.
Every plant species has encountered natural
mutagens, including certain types and levels of
ionizing radiation and chemicals, throughout
its natural history and has evolved mechanisms
for preventing, repairing, and minimising the
impacts of mutations caused by such agents. But
plants have not evolved mechanisms to repair or
compensate for the insertional mutations that
occur during genetic modification. Also, the high
frequency of mutations caused by tissue culture
during the GM process is likely to overwhelm the
repair mechanisms of crop plants.
Natural recombination events that move large
stretches of DNA around a plant’s genome do occur.
But these involve DNA sequences that are already
part of the plant’s own genome, not DNA that is
foreign to the species.
“Conventional breeding is more disruptive
to gene expression than GM”
GM proponents cite studies by Batista and
colleagues 23 and Ahloowalia and colleagues10 to
claim that “conventional” breeding is at least as
disruptive to gene expression as GM.24 They argue
that if we expect GM crops to be tested extensively
because of risks resulting from mutations, then
governments should require conventionally bred
plants to be tested in the same way. But they do
not, and experience shows that plants created
by conventional breeding are not hazardous.
Therefore crops generated by conventional
breeding and by genetic engineering present no
special risks and do not require special testing.
This argument is based on what appears to be
an intentional misrepresentation of the studies
of Batista and Ahloowalia. These studies did not
compare conventional breeding with GM, but
gamma-ray-induced mutation breeding with GM.
The research of Batista and colleagues and
Ahloowalia and colleagues actually provides
strong evidence consistent with our arguments,
above, indicating that mutation breeding is
highly disruptive – even more so than genetic
modification.
Batista and colleagues found that in rice
varieties developed through radiation-induced
mutation breeding, gene expression was disrupted
even more than in varieties generated through
genetic modification. They concluded that for the
rice varieties examined, mutation breeding was
more disruptive to gene expression than genetic
engineering. 23
Thus, Batista and colleagues compared two
highly disruptive methods and concluded that
genetic engineering was, in the cases considered
in their study, the less disruptive of the two
methods.
The GM proponents used the work of Batista
and colleagues and Ahloowalia and colleagues
to argue that, since mutation breeding is not
regulated, genetic modification of crops should
not be regulated either. The amusing part of their
argument is that they represent the mutationbred
crop varieties as “conventionally bred”,
not even mentioning that they were generated
through exposure to high levels of gamma
radiation. They then argue that, since these
supposedly “conventionally bred” varieties are
disrupted similarly to the GM varieties studied,
it was not justified to require GM crop varieties
to be subjected to safety assessment when
GMO Myths and Truths 16