Genetically Modified Organisms (GMOs) and Agriculture

GMOs (genetically modified organisms) are not allowed within organic foods or organic production systems. GMOs can be a controversial topic, as there exists many claims regarding the benefits of genetic modification (GM) for agriculture. These claims include:

GMOs are an extension of natural breeding and do not pose different risks from naturally bred crops
They are safe to eat and can be more nutritious than naturally bred crops
They are strictly regulated for safety
They can increase yields
They can reduce pesticide use
GMOs bring farmers economic benefits
They can benefit the environment
They can help solve problems caused by climate change such as drought resilience
GMOs will help feed the world.

Despite these claims, there is a body of research that suggests otherwise.

What are GMOs?

GMO stands for Genetically Modified Organism. It is defined as “the genetic material has been altered in a way that does not occur naturally by mating and/or natural recombination”^[1].

This typically involves the laboratory manipulation of genes at a cellular level with the insertion of one of more new pieces of DNA. DNA is short for deoxyribonucleic acid. It is the main component of an organism’s genome. The genome carries all the genetic information that characterises the organism and is found in the nucleus, mitochondria and chloroplasts (of plants) of every cell. DNA is made out of four distinct subunit ‘bases’ that are uniquely sequenced to code the 21,000 different genes that ultimately make up the human body.

Some of the more common genetic manipulations are:

Transferring of genes from related and/or unrelated organisms (transgenesis)
Modifying information in a gene (gene editing)
Moving, deleting, or multiplying genes within a living organism
Splicing together pieces of existing genes or constructing new ones^[2]

How do GM crops differ from conventionally bred crops?

GM crops are technically and conceptually different from naturally bred crops and pose different risks depending on what type of genetic manipulation has occurred.

Natural breeding can only take place between closely related forms of life. Traditionally, this occurs through cross pollination and selection over multiple generations. You can breed wheat with wheat, wheat with rye to make triticale, but you cannot naturally breed wheat with tomatoes, for example.

Transferring and inserting new DNA into a genome is not limited to just “sticky-taping” it together.

The gene of interest is isolated and propagated by GM Bacterium.
The gene of interest is bound with promoters (start of gene) and a termination element, normally from a plant virus such as cauliflower mosaic virus (CaMV):
1. More potent gene promoters allow the GM gene to be expressed at higher levels and in turn higher production of the GM protein.
1. Sometimes promoters may be from bacterium or animals and further modified.
1. Sometimes promoters are a mix of bacteria, virus, plant and animal DNA.
Recipient plants are grown as a tissue culture before the GM DNA is introduced:
1. GM genes are inserted through two main methods:
  1. A gene gun that shoots microscopic gold nanoparticles coated in GM DNA into plant cells hoping to target the nucleus and DNA particles.
  1. Cells are infected with bacterium A. tumefaciens, a bacterium that infects plants at wound sites causing crown gall disease and inserts GM DNA into plant when successful.
Modified plant cells are selected for:
1. Depending on the marker genes selected for (herbicide or antibiotic resistance), they are then treated with this product to kill all the plant cells that haven’t incorporated the GM DNA properly.
Plant cells are treated with synthetic plant hormones to proliferate and differentiate into small GM plants.
Any deformed plants are discarded, and remaining plants are tested to ensure they contain specific GM DNA.
From the hundreds or thousands of initial plants, a few are finally selected for further breeding.
At this stage, the GM plants have not been assessed for health and environmental safety or nutritional value.

It must be highlighted that the GM DNA will be inserted at a different location in the genome for each plant. The GM gene will express at different levels in different GM plants and even in different parts of the same GM plant^[3].This is not a precise technique and may have unexpected consequences^[4].The randomness of GM DNA insertion maximises chances that the host plant’s gene function will be disturbed, with potential downstream consequences of composition and performance^[5]. A single change to DNA can cause multiple changes within an organism (pleiotropic effects), as genes do not act as isolated units, but rather interact in a highly complex way^[6]. For a single GM DNA insertion, there is a 53–66% probability that there will be an unintended disruption to the plant gene^[7]. The risks associated for this remain extremely high for both cisgenesis and transgenesis^[8].

This is especially worrying in a crop like a tomato, where the leaves are naturally toxic, whilst the fruiting body is edible.

Are GM crops safe to eat?

The majority of GM crops are used as animal feed however a considerable percentage is still consumed directly by humans, mostly through oils^[9].

No regulatory body has ever required human toxicity studies to be carried out on GM crops. The assumptions about the safety of GM crops are constantly being challenged by new evidence.

Feeding studies in mammals with GM Bacillus thuringiensis (Bt) crops have found adverse effects, such as:

Toxic effects or signs of toxicity in the small intestine, liver, kidney, spleen, pancreas^[10]^[11]
Disturbances in the functioning of the digestive system^[12]
Increased or decreased weight gain compared with controls^[13]
Male reproductive organ damage^[14]
Blood biochemistry disturbances^[15]
Immune system disturbances^[16]

The issue with promoters such as cauliflower mosaic virus is that they promote gene expression in all different types of cells. This is beneficial for herbicide resistant GM crops, however undesirable for GM plants that contain the Bt toxin, lethal to several orders of insects. This gene is expressed in all parts of the plant, root, leaves, fruit and pollen. Through the GM process, plants themselves become the pesticide to all who eat it^[17]. This has revealed toxic effects in animal feeding experiments and human cells in vitro. GM Bt toxin does not reliably break down in the digestive tract^[18] and has been found circulating in the blood of pregnant women^[19]^[20]. GM Bt is a non-specific toxin that is not limited to insects and affects human cells^[21].

The uproar of foreign and synthetic DNA in GM crops has led to focus shifting to cisgenisis – transferring genes from a related organism or the same organism (wheat and triticale for example). However, though the main gene may be from a similar plant, this must be linked to the plant which is typically done with viruses, bacteria or other organisms rendering it a cross species transgenic process regardless. The effect of cross species DNA insertion and single gene disturbance are not predictable regardless of the type of GM DNA used. They are potentially unpredictable in the environment, can cause nutritional disturbances, and can lead to unexpected toxic or allergenic effects^[22].

Are GM crops strictly regulated?

GM crops have been allowed in non-organic agriculture since the 1980s, with the first GM Bt crops grown in Australian in 1996. The risks associated with GM crops are acknowledged by over 166 countries worldwide within the The Cartagena Protocol on Biosafety^[23], seeking to protect biological diversity. Additionally, the United Nations food safety body, Codex Alimentarius, advocate the continued safety assessments for GM organisms in all food and fibre^[24]^[25]. However, agreement regarding whose job it should be to ensure long term trials are completed and ensure its safety remains questionable.

All current GM releases rely on safety testing done by the company that wishes to commercialise the genetically modified organism (GMO) in question. Within the US this is voluntary. Within the EU this is weak, and within Australia FSANZ review GM crops prior to commercialisation. However, FSANZ do not commission their own independent safety tests or protocols on GM crops prior to commercialisation, instead, they base decisions on studies commissioned and controlled by the same companies set to make a profit from. Industry studies have inbuilt bias. The most well-known example of this is tobacco where regulations were delayed for decades due to confounding medical recommendations paid for by to tobacco industry itself^[26].

Do GM crops bring farmers economic benefits?

Genetically modified crops are covered by patents which monopolise the seed market and can have negative economic consequences in the agricultural sector. The main benefactors of GMOs are large corporations that hold exclusive patents to the technology and the required chemical inputs^[27]. The economic impacts on farmers themselves remains a mixed discussion with initial profits often negated by increased weed resistance, the high price of inputs (herbicide and chemical fertiliser) and the high price of GM seed. The negative effects of high GM seed price are amplified in developing countries where this presents a larger proportion of costs^[28].

Once the GM seed has been developed, the company has a patent on the product, forbidding farmers from saving the seed to plant the following year and monopolising the market. This has even led to litigation cases against farmers, and even neighboring farmers where GM crops have cross pollinated with non-organic crops^[29]. It is arguable that patents should not exist within the agricultural system whose sole base is to ensure continual food security.

Organic agricultural systems have been shown to be more conducive to food security in Africa than chemical-based production systems and are more likely to be sustainable in the long term^[30].

Do GM crops benefit the environment?

Numerous studies have found that the environmental impacts of GM crops are more adverse than their non-GM counterparts^[31]. GM Bt toxins have been found to have toxic effects on butterflies and other non-target insects^[32]^[33]^[34], beneficial pest predators^[35]^[36]^[37], bees^[38], aquatic organisms^[39] and beneficial soil organisms^[40].

Releasing GMOs into the environment is irreversible. Compared to chemical pollution that diminishes and breaks down over time, GMOs are living organisms and readily propagate, potentially passing on their genes to future generations and other organisms in the environment.

Will GM crops solve climate change?

There have been claims that GM herbicide-tolerant crops are more environmentally friendly because they allow farmers to adopt no-till systems, decreasing the need for mechanical ploughing and potential soil carbon loss. However, GM crops are not needed to practice no-till, and their introduction has not led to a significant increase in no-till systems or soil carbon^[41].

Genetically modified crops have not increased the efficiency of photosynthesis or produce more energy from the same amount of sunlight. The herbicide load associated with chemical-based agriculture and GM crops contributes to over 20% of agricultural greenhouse gas emissions^[42].

Climate change is not a singular natural phenomenon, rather it encompasses increased drought, flooding, heat, wind, and resistance to pest and disease within its trials. Increasing resilience to climate change doesn’t represent a singular gene, rather a combination of complex traits that interact. In most cases, plants are conventionally bred to increased resilience before GM traits are then incorporated. Numerous non-GM varieties have been shown to be as or more drought tolerant than GM varieties for this reason^[43]^[44].

What about natural Bt and mutation breeding allowed in organic farming practices?

GM Bt is different to the Bt spray allowed within organic agriculture both in terms of structure and mode of action^[46]. GM Bt is 40% structurally different to natural Bt, it is a shorter protein^[47], with decreased selectivity (can kill natural predators not just herbivores) and is in turn more toxic and allergenic. To highlight the sensitivity of genes, changes in the three-dimensional shape of the protein alone can turn harmless proteins into toxins^[48]^[49]. Natural Bt breaks down in sunlight and is a protoxin, this means it is only harmful when subjected to certain conditions like insect gut enzymes^[50].

Buying certified organic products is the best way to avoid genetically modified ingredients. Organic farmers aren’t allowed to plant GM seeds, GM animal feed, or any GM ingredients.

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