GM crops are not scary.

They’re an integral part of our agricultural future.

Jamie Attenborough
Nov 13, 2017 · 6 min read
A hysterical cob of corn being modified, apparently. Image source: laoblogger

We live in a fascinating period of scientific growth, especially in the blossoming fields of biotechnology; but, at the same time, this growth has resulted in a disconnect between public understanding and scientific consensus. This is true for the debate surrounding genetically modified organisms (GMOs), vaccines and numerous other biotech applications. Genetically modified (GM) crops fall under this same contentious umbrella, and the following post aims to breakdown the basics of GM crops, their current role and the misunderstood nature of their application.

An introduction to genetic modification.

Since Halloween is still on my mind, this is a plasmid costume. Plasmids are small rings of DNA that genes can be “cut and paste” into. Image: Promega Blog

When the term GM is used, it is generally referring to an organism which has had foreign DNA engineered into it, normally to gain a function. Arguably, the very first modified organisms were bacteria which carried genes from other species in small rings of DNA called plasmids (pictured, somewhat abstractly, above).

Plasmids naturally occur in many bacterial species, but engineered plasmids were made possible by the discovery of restriction enzymes: proteins which are used by bacteria to cut up invading DNA. Once discovered, scientists learned that the cutting of restriction enzymes was site-specific, meaning you could choose combinations of enzymes to cut out different genes. This allowed for the birth of the process known today as “cloning”; where a gene can be cut out of its genome and pasted into a bacterial plasmid, after which the bacteria containing the modified plasmid replicates millions of times, making millions of copies of the gene.

Genes are usually selected because they code for a protein which provides a positive trait, like preventing disease, or adding nutritional value.

Once prepared appropriately, the desireable gene must be inserted into plant or animal cells. This can be done in a multitude of ways, including gene guns, and, specific to plants: modified bacteria that insert the desired DNA into the cell. After this, the cells grow into the full organism, which is what we colloqially call a GMO. Newer technologies, like the CRISPR-Cas9 system and RNAi techniques, allow for direct modification of the genome and/or its activity; giving researchers the ability to control how, when and if target genes are expressed.

You can read about the details of the process here:

Why do we need GM crops?

The numbers vary from region to region, but on average, around 20–40% of potential crop yields are lost annually. Given the rapidly increasing state of the global population, especially in the disease-rich tropics, such losses severely hamper the ability of food production to meet demand. Although yield is affected by a variety of social and environmental issues, GM crops that are resistant to environmental stressors, like pests and disease, help to minimise crop losses.

An example of this is the variety of Bt crops now available. Bt is short for Bacillus thuringiensis: a bacterial species that infects the guts of insects. In the 1960’s, the proteins responsible for killing the infected insects were isolated from B. thuringiensis and used to make insecticides. Because these Bt proteins were specific to only certain insect species at working concentrations, and therefore safe for mammals and other insects, the genes for the proteins were engineered into plants by the late 1990’s. The resultant GM crops were resistant to insect-borers (pictured below).

a) European corn borer leaf damage, b) damage and fungal infection in non-Bt maize (left) and Bt maize (right), c) an example of stalk tunnelling and d) the adult male and female borers. Source: Hellmich and Hellmich, 2012.

Bt crops are not the only GM plants on the market, but due to their observed benefits to yield and reductions in cost, they have been applied extensively: accounting for 70–80% of the maize crop in South Africa and over 77% of the maize crop in the US. The only other major commercial GM trait is herbicide resistance (many GM crop strains have both herbicide and Bt-mediated insect resistance), but there are hundreds of GM crops either being developed or on the market; with traits including increased nutritional content, drought tolerance and viral resistance (see below for GM papaya).

A block of healthy GM papaya trees surrounded by dying non-GM papaya trees after exposure to the papaya ringspot virus (PRSV). Papaya plantations in Hawaii were nearly wiped out by PRSV in the early 1990's, but the introduction of resistant, GM papaya saved the industry. Source: Gonsalves et al., 2000.

How do we know GM crops are safe?

For a GM crop to make it on to the market, the crop must undergo testing (including multiple studies on its environmental and health impact), as well as governmental review. Most countries follow the international Codex Alimentarius standards, and, in general, it takes 5–10 years for a GM crop to make it through developmental testing, then several years more of government review. A review of all GM crop safety studies published from 2003–2013 found no significant health risks, and in 2016, The National Academies of Science (US) published an extensive, 500+ page review on GM crops: also finding no link to health consequences.

Why then, over 30 years on, are GM crops still reviled?

Countries where domestic GM crop production is approved, commercial or otherwise, are represented in green. Most of the EU is represented in orange; as these countries, although not individually approving GM crop production, cannot, under EU law, prevent the use of approved GM seed in their territories*. Source: ISAAA. *Countries must object to the GM crop during approval review.

Over 70 governments have GM crop approvals of some sort (either allowing import, research or production), but the number of governments approving domestic production of GM crops is below 40 (see above image). This aversion to GM crop growth is somewhat due to applied pressure by the public, wherein anti-GM sentiment has grown rapidly in recent years. Why is this so? Here are, in my opinion, 5 major reasons:

  1. Environmental concerns. In 2016, over 100 living Nobel Laureates wrote a letter accusing Greenpeace of misrepresenting GM crops at the cost of millions of lives in the developing world. Many anti-GM activists claim GM crops pose an environmental risk, but numerous studies on the matter have not shown any conclusive evidence; other than cases of increased insect/weed resistance, which can be managed.
  2. Rejection of scientific results on safety. Many anti-GM activists refer to anecdotal experience and discredited research to support a “dangerous GMO” hypothesis, rejecting scientific consensus on safety as flawed.
  3. Monsanto fervour. Monsanto, which is the largest seed producer globally, has long had a bad reputation among anti-GM activists. The conspiracy theories and pseudoscience are not worth discussing, but you can read an example of the Evil-Monsanto stance here.
  4. Dependence on large corporations. There is valid concern over the development of seed-monopolies. However, this is combatted by governments incentivising domestic research and production, along with a strong competition commission — not by banning the technology.
  5. The rise of Big Organic. The organic industry has grown from strength to strength in recent years, and the rigid, “natural” ideology which guides its followers has long had an anti-GM base. If you’d like to hear more about the pros and cons of organic farming, you can read one of my earlier posts on the matter.

Looking to the future:

Dr Jill Farrant, whom I studied under at the University of Cape Town, gives a TED-talk about desiccation-tolerant plants and what we can learn from them. Dr Farrant’s lab is one of many working towards solutions for growing crops in our increasingly dry climates.

There is no doubt that the coming century will provide a number of novel challenges for humanity, but the combination of a growing population and a changing climate stands out, for me at least, as the greatest challenge of all. Biotechnology allows us to adapt our crops for the coming changes with a precision that conventional breeding techniques cannot provide. Although GM crops alone are not a solution — they stand to play a vital part in our future food security.

Given all that has been discussed above, there is no valid reason for the global community to reject plant biotechnology. In fact, the current lack of enthusiasm for GM crops could limit our abilities to combat future crop failure, and, in doing so, unnecessarily put millions of lives at risk.

Whether they’re liked or not, GM crops are here to stay.

Your Science

Communicating science stories — a publication devoted to scientific breakthroughs, their background, and the sustainable future technology will provide.

Jamie Attenborough

Written by

Molecular biology grad currently chipping away at a Masters. Review pieces, critiques and musings with an eye on the future — opinions are my own | 📍NZ

Your Science

Communicating science stories — a publication devoted to scientific breakthroughs, their background, and the sustainable future technology will provide.

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