Report on Genetic Engineering
Genetic engineering has been a hotly debated topic in politics as well as society in the past decades and
still is today.
Arguments like the nutrition of a growing world population due to a declining infant mortality rate or the
loss of
considerable areas of arable land due to erosion or pollution damage keep fueling the debate whether
genetically modified
organisms (GMO), especially crops, are needed to sustain the global demand for food. On the opposite, concerns
have been raised
concerning the potential adverse effects on human health and environmental safety. Besides the facts, part of
the public debate
is based around ethical questions and trust issues towards institutions and authorities. There have been
studies and surveys
carried out addressing many of these topics and additionally a diverse cluster of organisations and the media
is bombarding the
public with contrary statements. This report tries to give an overview on humanities relation to changing
genetics, a brief
summary of used methods, and gathers statements from scientists and authorities. It is meant as the
motivational basis for this
years Marburg iGEM team´s Public Engagement and Human Practice efforts.
History of Genetic Modification
Our ancestors had no conception of genetics but still were able to influence the genes of multiple
organisms.
It is a
process known to everybody called artificial selection or selective breeding. Those individuals with the
most
desirable traits,
like the biggest and most delicious fruits or the highest loyalty, is chosen to propagate and produce
offspring. This process
is repeated over several generations and the result is an organism with the selected traits. The dog,
existing
today in many
variations, is believed to be the organism our ancestors selectively bred first at around 32,000 years
ago (Zimmer,
2013). And there are many more instances like corn which originates from a grass called teosinte with
very few kernels (‘Evolution of Corn’,
n.d.). However, this process is not considered GMO technology today. What we understand under genetic
modification today can be traced back to
the mid 1900´s
when scientists discovered that genetic material can be transferred between different species
(Avery, MacLeod, & McCarty, 1944),
the structure of genetic material was identified as a double helix (Crick, Watson, & Bragg, 1954), the genetic code was
deciphered (Nirenberg, Matthaei,
Jones, Martin, &
Barondes, 1963) and finally a DNA recombinant technology was described (Cohen, Chang, Boyer, & Helling, 1973). Only a few
decades after these
ground-breaking discoveries were made, the first
genetically modified (GM) plants were produced in 1983, which were antibiotic resistant tobacco and petunia
(Bevan & Chilton, 1982; Fraley,
1983; Herrera‐Estrella
et al., 1983).
Soon, the first GM plants were commercialized: in the
early 1990´s China approved modified tobacco and in 1994 the United States Food and Drug Administration
(U.S.
FDA) approved
the “FLAVR SAVR” tomato which was modified to have a longer shelf live by delaying ripening. Today numerous
GM
plants exist
and are in use, covering popular fruits like papaya, melon and apple, flowers like roses, feed plants like
sugar beet,
vegetables like tomato, maize and potato and even cotton for clothes production
(‘GM Crops
List—GM Approval
Database | ISAAA.org’, n.d.).
Current numbers on GM crops
World
As stated above, many GM crops are relevant for food production today, be it indirectly for
feed in
production lines or directly as consumables. In 2018, 26 countries planted 191.7 million hectares worldwide
with GM crops,
which is an increase of 1% from 2017´s worldwide planted area. Accordingly, since its first
commercialization
in 1996 with
1.7 million hectares planted, GM crop area increased by an approximate 113-fold. The accumulated area
planted
with GM crops
from 1996 to 2018 was 2.5 billion hectares. This makes biotechnology the fastest adopted crop technology in
the world. Of
the 193 member nations of the United Nations Organisation (UNO) 42 nations plus the European Union (EU)
adopted GM crops,
of which 26 countries (21 developing and 5 industrial) planted and 44 imported GM crops. The four major GM
crops, namely
soybeans, maize, cotton and canola, occupied 99% of the GM crop area (Figure 1). GM crops share in total
crop
area was 78%
for soybeans, 76% for cotton, 30% or maize and 29% for canola. 42% of the global GM crop area was planted
with
stacked trait
crops tolerant to various herbicides and pesticides. Around the world the GM crop area was unevenly
distributed with the top
five countries United States of America (USA), Brazil, Argentina, Canada and India planting 91% of the
global
GM crop area.
In the EU, the two nations Spain and Portugal planted the GM crop MON810, which is an insecticide resistant
maize, together
covering 120.990 hectares. 95% of the area was planted by Spain. From 2017 to 2018 GM crop area in the EU
has
decreased by
8% from 131.535 hectares (Figure 2). Nevertheless the EU imported GM crops, roughly 30 million tons of
soybean
products,
10 million tons of maize and 2.5 million tons of canola originating from Argentina, Brazil and the USA.
Since
1992, across
the world 4.349 approvals to GM crops have been issued, of this being 2.063 for food, 1.461 for feed use and
825 for
cultivation
(‘ISAAA Brief 54-2018: Executive Summary | ISAAA.org’, n.d.).
Germany
In Germany, there is no more GM crop farming since 2012. GM maize has been planted last in 2008
(3.171 hectares, 0.15% of total maize area in Germany) and GM potatoes have been planted last in 2011
(2 hectares, 0.0008% of total potato area in Germany). GM crop area never made up more than 0.02% of land
used
by
agriculture in Germany
(‘Gentechnik’, n.d.).
Modern Methods in Breeding
The traditional way of breeding, as explained above, although generating many domestic plants and animals,
is
relatively
slow and limited by the available traits individuals express. Modern breeding methods enhance the trait
spectrum and the pace
in which new traits can be discovered and implemented to crops or animals.
Plant Mutagenesis
As it is known that practical breeding depends on genetic variation plant mutagenesis expands the
variability of
traits.
Variations found in nature do not represent the original spectra of spontaneous mutation due to the fact
that
they are
recombining within populations and interacting with environmental factors. In the process of mutagenesis
heritable changes
occur in the genetic information induced by mutagenic agents called mutagens. These mutagens can be of
chemical,
for
instance substances interacting with the DNA, or of physical origin, such as ionizing radiation
(Oladosu et al., 2016).
After using the mutagen on the crops, mostly seeds, seedlings or cell cultures from which single cells can
be
grown out,
screening has to be done to see if changes in traits have been achieved by mutations. These mutations can be
DNA
double
strand breaks, single base exchanges or alkylation of bases. In most cases, generated mutants are
heterozygous,
because
the mutation happened in only one allele. Therefore the breeder needs to rear subsequent generations to
evaluate
recessive
mutations. Selection then takes place in form of phenotypical, physical or molecular test to determine for
instance plant
height, earliness of maturity and biochemical composition. Mutagenesis breeding has impacted agriculture
massively, with
more than 3.300 entries to the Mutant Variety Database
(‘Mutant
Variety Database’,
n.d.),
covering all major food and feed crops.
Genetic Engineering
This term is used to describe methods which alter the genetic makeup of an organism using DNA recombinant
technology.
This technology resorts to enzymatic tools called restriction enzymes. These cut the DNA site specific and
can
thereby
isolate genetic constructs coding for desirable traits. When gene(s) are introduced into an organism this
can be
achieved
either directly or indirectly. The direct approach utilizes a method called microparticle bombardment
(Sanford, 1990).
Developed in the 1980´s, engineered DNA is coated on microparticles of either gold or tungsten and then
shot with high velocity at the target organism using high pressure helium gas. The DNA fragments can then be
incorporated
into the organism’s genetic material. There are other direct methods such as electroporation or
microinjection
but particle
bombardment is the most effective. The indirect approach makes use of a vector: the soil bacterium
Agrobacterium
tumefaciens
naturally infects plants and alters its hosts genome via a plasmid called Ti-plasmid. This plasmid can be
engineered to carry
genes coding for a desired traits instead of its natural genes for infection. With the development of a
method
called
CRISPR/Cas9 and other variants genetic engineering in plants got much easier
(Cong et al., 2013;
DeMayo & Spencer, 2014;
Ran et al., 2013).
This system is found in bacteria where it serves as a defence mechanism against viruses. The endonuclease is
guided to its
target cutting site via a guide mRNA where it induces a double strand break (DBS). The DBS can be repaired
in
two distinct
ways. Non-homologous end joining leads to a small deletion while homologous recombination allows for the
integration of
donor DNA into the endogenous DNA. Thereby, the CRISPR method allows for small alteration or hole gene
insertions at target
sites.
At this point it may be appropriate to introduce the two terms “cisgenic” and “transgenic”. While
“transgenic”
refers to organisms in which genetic material outside the species boundary, originating from a donor
organism
which is
sexually incompatible to the engineered organism, has been inserted.“Cisgenic” on the contrary describes
genetic
modifications within the boundaries of sexual compatibility. Therefore, cisgenic plants are similar to
traditionally bred
plants (Schouten, Krens, & Jacobsen,
2006). The most
obvious example
of transgenic plants are the many varieties of so
called “Bt” crops. Standing for Bacillus thuringiensis, into these plants a gene from the bacterium was
integrated which
leads to the production of a crystal protein that is toxic to specific pest insects
(‘Insecticidal
Plants’, 2015).
Opinions on GMOs
There are many scientific publications evaluating specific GMO traits towards the environment and health
safety.
Additionally many reviews exist summarizing GMO effects to a much broader scale possible here
(Bawa & Anilakumar, 2013;
Nicolia, Manzo, Veronesi, &
Rosellini, 2014;
Snell et al., 2012;
Zhang, Wohlhueter, & Zhang,
2016).
In many of these, authors conclude that the application of GMO offers great opportunities but still has to
be
carried out
with precautions. A simple “yes” or “no” cannot be given
(Zhang et al., 2016). Still, due
to the partly
contradictory
evidence, it cannot be said there is a consensus among scientists, according to
Hilbeck et al., 2015.
Benefits of GM crops
Humanity faces several challenges in the coming decades. Among them are the increasing world population, a
decrease of
arable land or the bottleneck of traditional breeding methods
(Zhang et al., 2016).
To all of these, GMOs pose a genuine answer. The easiest way to produce more food for a growing population
is to
increase
productivity by earlier maturity, easier harvesting, processing and cultivation. Adding to that, if we
resorted
to
organically producing todays yields, humanity would need to cultivate an additionally 3 billion hectares,
which
is the
equivalent to the size of two South America’s
(‘Time to call
out
the anti-GMO conspiracy theory – Mark Lynas’, n.d.).
But food also needs to become nutritious. A good example here is “Golden Rice”
(Ye et al., 2000),
which produces a precursor of vitamin A. The deficiency of vitamin A is estimated to kill more than half a
million
children under the age of 5 each year
(Black et al., 2008)
and cause another half million irreversible cases of childhood blindness
(Humphrey, West, & Sommer,
1992).
Risks of GM crops
GMOs pose risks to its consumer as do crops deriving from traditional breeding. Major risks are toxicity,
allergenicity and genetic hazards emerging from the inserted or altered gene itself, the expressed protein,
products
of the metabolism, pleiotropic effects or the disruption of natural genes in the organism
(Zhang et al., 2016).
There have been reports on the strong allergenicity of “Starlink” maize, which is directly connected to the
inserted gene
from Bacillus thuringiensis
(Bravo, Gill, & Soberón,
2007;
Sanchis, 2011;
Tabashnik, 1994;
Werth, Boucher, Thornby, Walker, & Charles,
2013).
Also, GM crops can have an adverse ecological influence. For example, the weed species Amaranthus palmeri
did
evolve a
glyphosate resistance after years of glyphosate use on resistant cotton fields
(Gilbert, 2013).
Another possibility is the fact, that insect resistant crops infer with ecological food webs by shifting
predator prey
ratios. Moreover, targeted pests might decline and primary minor pest become major issues
(Bawa & Anilakumar, 2013; Snow &
Palma, 1997).
Statements from Authorities
The Public Acceptance of Agricultural Biotechnologies (PABE) project revealed a range of questions
concerning
rather institutional considerations of the public, such as who is befitting from GMO use, by whom
consequences
have
been evaluated, if authorities have enough power to regulate large companies and why the public has not been
better
informed about their use
(Marris, 2001).
For this reason, an overview of institutional statements might be appropriate.
The European Commision (EC) published the book “A decade of EU-funded GMO research”. Within this endeavor
more
than
200 million Euro of research grants were spent to evaluate GMO´s in areas such as environmental impact, food
safety,
biomaterials and biofuels and risk assessment and management. It conclusively states: “The main conclusion
to be
drawn from the efforts of more than 130 research projects, covering a period of more than 25 years of
research,
and
involving more than 500 independent research groups, is that biotechnology, and in particular GMOs, are not
per
se more
risky than e.g. conventional plant breeding technologies.”
(Publications
Office of the European Union, 2010)
The National Academy of Sciences founded by the U.S. Congress summarize in their comprehensive report, that
large
numbers of animal feeding studies provided reasonable evidence that animals were not harmed by food derived
from
GM crops,
although admitting some studies were not designed optimal. Furthermore, long-term data in livestock health
before and
after GM crop introduction did not show adverse effects associated with the crops. And at last,
epidemiological
data on
cancer and human health over time was revised but no substantiated evidence was found that GM crops are less
safe than
foods from non-GM crops.
(Read "Genetically Engineered Crops,
n.d.)
The British Royal Society states the following to the question “Is it safe to eat GM crops?” on its website:
“Yes.
There is no evidence that a crop is dangerous to eat just because it is GM. There could be risks associated
with
the
specific new gene introduced, which is why each crop with a new characteristic introduced by GM is subject
to
close scrutiny.
Since the first widespread commercialisation of GM produce 18 years ago there has been no evidence of ill
effects linked to
the consumption of any approved GM crop.” Before new GM foods are permitted to the market a variety of test
has
to be
completed and the results are used by the authorities to determine the safety of the GM product, making “new
GM
crop
varieties at least as safe to eat as new non GM varieties, which are not tested in this way.”
(‘Is it safe
to
eat GM crops?’, n.d.)
Conclusion
As biologists, using genetic engineering methods every single day, they are quite natural to us.
Nevertheless,
we are
confronted with the public debate too. Having experienced the public aversion towards GMO ourselves and
having
red about
the many proposed justifications against it we realized that a direct exchange between the public and
experts
from all
fields as well as diverse interest groups might provide a good common ground for an open discussion. In this
way
we hoped
the perspective of being indoctrinated reflected my public studies might be avoided.
