Gene editing – a “precision selection” technique

The Oireachtas Joint Committee on Agriculture, Food and the Sea met this evening (Wednesday March 9) for an extensive discussion on gene-editing technology and its potential role in sustainable food production for a population growing world.

The committee heard from a number of experts, including Dr. Thomas McLoughlin, Dr. Barbara Doyle Prestwich, Dr. Raghu Badmi and Dr. Patrick Harrison, as well as witnesses from Teagasc and the Department of Environment, Climate and Communications.

Representing Teagasc on the committee, were its director, Professor Frank O’Mara; Crops, Environment and Land Use Program Manager John Spink; and the head of the crop research department, Dr. Ewen Mullins.

For the purposes of this article, we are interested in the contribution to the committee of Teagasc, who described gene editing as a “precision breeding” technique for improving the performance of an organism.

The particular type of gene editing referred to here is called “CRISPR-Cas” and consists of two parts:

“First, a ‘molecular scissor’ used to cut DNA and second, a molecular ‘navigation system’ to guide the ‘scissors’ to the specific gene.

“Together, these two parts form the ‘CRISPR-Cas’ machinery that can be used to modify a single gene or, if necessary, dozens of genes at the same time.”

Gene editing potential

But from a practical and dietary point of view, what does all this mean?

When it comes to crop breeding, Teagasc said gene editing can allow breeders to deliver a range of traits.

These traits include performance improvement; disease resistance; or quality improvement.

“An important point to emphasize is that editing an existing variety enhances the value of that variety to the farmer or processor, without changing any of the other traits of the original variety.”

For example, many existing potato varieties meet processing and cooking requirements, but lack long-lasting resistance to late blight.

Due to this sensitivity, the crop should be sprayed approximately 12 times.

But gene editing can make precise changes to potato DNA that can increase resistance to late blight and other potato diseases, without compromising any of the variety’s important qualities.

Another example cited by Teagasc concerned the editing of a single gene in wheat – the mlo gene – which results in the creation of a variety resistant to late blight.

“In its natural state, this gene makes wheat susceptible to late blight, which can decrease yield potential. By modifying the mlo gene, the researchers disabled the mlo gene and improved the existing variety by giving it resistance to an important disease, without affecting the yield potential of the variety.

Using conventional breeding techniques this is not possible as each step in the breeding process will alter thousands of genes at once.

Recognizing the objectives of the Green Deal and the European Commission’s Farm to Fork Strategy of a 50% reduction in the use of chemical inputs and 20% reduction in nutrient inputs on cropping systems, “all available innovations, technologies and tools must be taken into account,” according to Teagasc.

And their potential is ‘real’, as evidenced by a Teagasc project that assessed the impact of a late blight-resistant potato variety generated using a new breeding technique.

“With this new potato variety, fungicide applications have been reduced from 12 sprays to two sprays per season.”

European Court of Justice
In 2018, the European Court of Justice ruled that organisms generated by editing should be considered genetically modified organisms (GMOs) within the meaning of EU Directive 2001/18. Thus, a new crop, such as the ones mentioned above, is technically defined as a GMO and must go through the regulatory system within the EU before commercialization.

“However, since the judgment of the European Court of Justice in 2018, the European Food Safety Authority has concluded that the editing techniques pose no more risks than conventional farming. A multitude of scientific organizations across the EU have come to a similar conclusion,” the Teagasc statement read.

He continued, while Teagasc is not in the business of marketing or promoting GMO crops, it is responsible for supporting the profitability and environmental sustainability of the sector.

“To achieve this, it is incumbent on us to study and assess the impact of new scientific developments, whether positive or negative, so that the sectors concerned and society as a whole can make an informed decision. objectives, specific to Ireland.”