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What is a GMO

October 2016

South African citizens have been exposed to 20 years of reports, discussions and arguments about GMOs. Some of this has been about science, some about risks and much about pro- and con-arguments; altogether, often creating more heat and confusion than clear understanding. Despite this, adoption of GMOs continues to expand, here and globally.

In a nutshell, this topic is where science, nature, consumers, producers, and markets meet. To set the stage, we start with definitions.


  • An organism is a living entity which is able to produce biochemical products, grow, multiply and convey its genetic traits to its offspring.
  • Biology and Biotechnology (a) deal with living things and scientific investigations on what they are and do, and how their genetic systems function; (b) the technology part refers to techniques to generate new knowledge and finding ways to employ such knowledge to the benefit of humans, animals and the environment.
  • Genetic modification (GM) is one part of modern biotechnology that enables humans to make changes in an organism’s genetics or to insert novel genes to generate more efficiency or new products ‘in ways that do not occur through natural cross-breeding and traditional selection’ for improving plants, animals or micro-organisms. These resultant GM organisms are known as genetically modified organisms or GMOs.
  • The Genome is the sum total genetic composition of an organism. It covers genes that contain codes of the DNA hereditary chemical which determines traits, other genes that control expression of functional genes, and genes located in minute organs inside cells.

Nature and science interaction
For thousands of years farmers and households have selected better plants for domestication and for improved foods though they could not see, identify or apply genes. In nature, ongoing climate change and impacts from pests and diseases led to survival of organisms that had undergone genetic mutations, such as the navel orange that was a mutated plant of common orange, or recent mutation in Australian cotton bollworm that caused resistance of its larvae to the Bt gene, as well as cross-pollination between related species, that provided genetic tolerance to these stresses – a process known as ‘genomic plasticity’.

Plant breeders still investigate wild ancestors for useful genes. Our present staple foods, animals and microbes all arose from ancient wild species. Duplicated and stacked genes used in breeding exist naturally in most plant species. Wild potato genes provide resistance to fungal disease in cultivated varieties. New knowledge, sophisticated diagnostic and computer software now enable us to better understand DNA systems, identify and isolate genes and transferring them from one plant species to another as DNA is common to all living organisms (except for some viruses that have RNA genetics).

This has become possible only after many decades of investigating how genetic systems work in nature.

How are genes moved between species?

  • Conventional cross-breeding between species or varieties and selecting desired offspring that appear more robust under stress or have better grain or fruit quality or yields in tests.
  • For other cases transporting genes (transgenes) require finding and describing genes that determine traits by using molecular diagnostics that enable identification of the gene’s specific code such as the Bt gene in a bacterium (Crystalline 1Ac gene for resistance to certain insects).
  • Isolating the targeted gene by way of an enzyme that neatly cuts it out from the DNA code.
  • Multiplying copies of the gene in automated laboratory equipment.
  • The lengthy code of a gene has a short DNA code in front, called promoter, that activates the gene to be expressed in specific tissue and a short DNA code at the end that stops the expression.
  • The transgene can be ‘shot’ into a plant embryo or plant cells by infiltration or by using a small circular piece of DNA that contains the transgene and let a harmless bacterium carry this DNA, called a construct, into plant cells.
  • Some plant cells will now contain the construct with the transgene that can latch onto the plant’s DNA where it may be expressed. Plant tissue or cells are then transferred to nutritious growing media in the lab to develop into plants.
  • Greenhouse and field testing these plants for stability and performance follow.

Some GMO achievements
Hybrid maize with yield potential of up to 20 t/ha under irrigation, resistance to stalk borers and tolerance to herbicides, thanks to improved genetics. Oilseed crops with improved oil composition for human health and cotton resistant to bollworm. Herbicide tolerant soybeans now facilitates conservation agriculture with minimum or no tillage and more rapid crop rotation.

The drought of 1991 - 1992 caused maize yield to fall to 0,85 t/ha or 3,0 million t/crop from 3,5 million hectares. The catastrophic drought of 2015 - 2016 gave us 3,73 t/ha or 3,73 million tons from only 1,9 million hectares thanks to superior genetics and improved farming systems. Altogether a 4,4 times increased efficiency.

How safe is South African GM maize?
Scientific assessments are conducted by a ministerial appointed GMO Advisory Committee while regulatory decisions are made by the GMO Executive Council comprising representatives from seven departments. Safety assessments include food, feed and environment, allergens, toxins and socio-economic impacts. Since the year 2000 some 40 million tons of GM maize grain have been produced on 18 million hectares without any substantiated adverse impact on humans, animals or the environment.

Farmers and the public should challenge parties that claim GM crops are risky and not useful for smallholder farmers to present scientific facts that old systems that caused famine due to low yields, pests, diseases and weed competition, are claimed to be best.

Article submitted by Wynand van der Walt, Senior Partner, FoodNCropBio Consulting Services.
For more information, send an email to wynandjvdw@telkomsa.net.

Publication: October 2016

Section: Pula/Imvula