We seem to see the use of genetically modified organisms (GMO) more and more in recent years. Most recently we’ve seen the first genetically modified salmon cleared to enter the food chain by the FDA and there is also GMO pork in development.
Genetically modified food is not permitted anywhere in the world. This is due to public weariness with polls showing 52% of people believe GMO foods are unsafe and a further 13% unsure.
This, I believe, is due to poor education of the public on GMO products. Take this video for instance (though take it for its humour value):
Biotechnology, the process of using organisms and biological processes to get a desired product, has been in use for thousands of years! It plays a huge part in a variety of industries and processes from making beer, cheese & wine, to extending shelf-life and producing antibiotics.
This point of this post is to explain how genetically modified plants could generate a huge number of useful products and how in a world of ever increasing populations, disease and climate change – how GMO plants may hold the key to our future! I chose to focus on plants because I believe they may hold the greatest potential. Why plants? well in an age where we need to reach carbon neutrality by the turn of the century, the energy is already in the plants. Natural processes of photosynthesis and respiration is driven by the sun.. so why not let them do the work for us?
There are some key plants that are very good platforms for genetic modifications for a number of uses. Maize (Zea mays), is on such plant, it is a domesticated cereal grain that has been grown as human and animal feed for thousands of years, it has also been used to produce ethanol starches and oils. It is one of the most widely used plants for GMO because it is widely regarded as ‘safe’, its genome and genetic properties is well characterised and it is very efficient as generating biomass due to its C4 photosynthesis. The only drawback I think of is that it is a wind pollinated plant. So there is the potential for outcrossing and bio-pollution of nearby un-genetically modified maize crops.
Plants as producers of pharmaceuticals is one of the most widely studied method of genetic modification. Plants offer an unprecedented opportunity to make ‘affordable’ pharmaceuticals on a global scale. There are currently two methods for expressing epitopes (the part out immune system recognises) of diseases in plants: stable integration approach and using plant viruses as transient vectors
- Stable integration approach relies upon the availability of a DNA sequence coding for a specific antigen and on the construction of an expression cassette for plant transformation.
- Plant viruses as transient vectors involves introducing a gene expressing the antigen (the bit that causes the immune system to create antibodies) of interest into a plant virus and subsequently infecting the plant.
Both of these methods result in the plant up-regulating an antigen which accumulates in parts of the plant. These parts can then be purified into a drug or administered crudely as an ‘edible vaccine’. It makes sense that the plant seeds are the most ideal storage device because of their longevity and the pharmaceutical proteins within them do not lose any of their activity. This is most impressive because it means that pharmaceutical containing seeds can be sent to the area experiencing a disease outbreak and cheaply distributed or even grown (matching local demand).
Enterotoxic Escherichia coli (ETEC) causes ~800,000 deaths every year in developing countries. In 60% of all ETEC strains the heat-labile toxin (LT) is found. Research back in 2001 was successful in expressing an LT antigen in corn, an immune response to ETEC was generated after being fed to mice.
An antigen for hepatitis B has also been expressed in tobacco and an immune response demonstrated after giving to mice. While very few of these plant derived vaccines are in trials it is clear that this type of vaccine could save many lives by being cheap to produce and accessible.
As i hinted at previously edible vaccines may be a thing of the future! If the antigen is expressed in or accumulates in the leaves then the leaves can simply be eaten. This is possible because of the cell wall of the plant protecting from the digestive enzymes of the human digestive system until it can be absorbed. There is however an issue with dosage control here.
Plat oils are sought after because there is no need for expensive refining, because unlike in fossil fuels, the oil can be extracted directly from the seed. This has led to the need for improved quality of plant oils by applying recombinant DNA techniques. Increasing the degree of mono-unsaturated fatty acids can enhance nutritional value and can reduce cholesterol in the blood.
Polyhydroxylalkanoates (PHAs) are used for the synthesis of biodegradable plastics. They are currently, however, only made by bacterial fermentation (an expensive process), this keeps the price of biodegradable plastics high. However when the relevant genes for production of PHAs were introduced into the plant Arabidopsis thaliana the production efficiency was greatly increased. In todays world there is much, well-place, concern about polluting the environment, this technique could provide an economically sustainable method of producing plastics that will degrade in the environment, thus reducing their impact on wildlife.
The biofuel industry is on that has received great attention in recent years. 95% of biodiesel production is done using food crops (such as; Soy bean, Rapeseed and Palm oil) and has therefore been blamed with driving the price of food crops up. It seems simple then that genetic modification should be applied to non-food crops in order to make these crops suitable for biofuel production. Micro-algae is another prime candidate for replacing food crops because the lipid content (which creates biodiesel) can be highly increased with genetic engineering.
Bioethanol is a key biofuel because it can be added to petrol and run in an engine without the need for engine modifications. Bioethanol is formed by the bacterial fermentation of sugars. Plants high in sugars (sugar cane) represent the best substrate for this. However the presence of lignin in the cell wall restricts the potential of this process by limiting the availability of cellulose and reducing the activity of cellulolytic enzymes. This means that ‘high-energy’ intensive pre-treatment is needed to breakdown the lignin. Researchers have been able to inhibit lignin by suppression of lignin producing enzymes. Meaning that there is a need for only one third of the treatment time and 3x less enzyme is need to release equal amounts of sugar.
I also wanted to bring you attention to the golden rice project which is attempting to genetically modify rice to contain vitamin A. Vitamin A deficiency leads to the deaths of around 1.15 million people worldwide, and is implicated in a number of other diseases. 54% of infant deaths worldwide is due to malnutrition, something which this golden rice project could significantly reduce.
The point of this post was to describe just a few of the non-food applications of genetic modification. It is clear that GMO have huge potential in combatting some of the worlds most prolific diseases saving many lives or reducing the impact that we as a species have on our environment.If this biotechnology were to gain more support resources and attention by explicitly educating the public than this potential may be achieved.