There's no proof that gene editing has made any contribution to drought tolerance or pathogen resistance – or will do any time soon. By Claire Robinson

Grand claims are made for the ability of gene editing and other new GM techniques to produce crop plants that improve the sustainability of our farming and food systems. A study published in January 2022 analyses whether these claims stand up – and finds that they don't.

The researchers examined the EU's sustainable development goals, linked them with relevant plant traits, and reviewed existing research and field trials with gene-edited crop plants for evidence that their intended traits were able to fulfil the sustainability goals. The researchers gave a particular focus to the sought-after traits of drought tolerance and resistance to fungal pathogens.

Drought tolerance

Regarding drought tolerance, the researchers noted that this is a complex genetic trait involving the interaction of many genes and that resilience in the face of drought stress is largely environment-dependent, with soil and weather conditions being the most important factors.

The researchers pointed out that drought tolerance is one of the most widely investigated traits in both older-style genetic engineering and new GM techniques ("new genomic techniques" or NGTs) but "thus far no NGT-based plants with drought tolerance traits are available on the market". They wrote, "Despite the long history of drought research, also classic transgenic plants with drought resistance traits are rare on the market — in the period from 2015 to 2019 only three have been newly approved or marketed."

They added that the maximum yield increase reported for drought-tolerant GM plants in field cultivation was just 2–4%, "which is comparable to conventionally bred varieties".

In other words, GM had made no positive contribution at all to drought tolerance in crop varieties.

Pathogen resistance

The researchers identified proof-of-principle studies and development of traits reported to provide pathogen resistance in the laboratory or greenhouse – but only two publications on field trials.

They found that few genes have been identified as conferring resistance to multiple pathogens and commented that only if this can be achieved will applying broad-spectrum fungicides be avoided in conventional farming. They added that new GM plants that can withstand more than one stressor or different environments – necessary for resilience in the field – "are not documented in advanced development states". That means they are still in the research and development phase and are not ready for commercialisation.

They noted that three supposedly pathogen-resistant new GM plants are approved for cultivation in the USA, but there is not enough data available to allow for conclusions on their performance.

Overall, the researchers concluded that developing new GM plants will not be sufficient to achieve EU sustainability goals and that development of a variety of agricultural measures "will need comparable attention and research efforts" to those currently applied to new GM plants.

The new study reinforces the findings of an earlier scientific review that concluded, "Despite the promise of new traits and techniques, GM crops, including gene-edited crops, are unlikely to meet either the narrow agronomic, or the broader social and environmental, requirements of sustainable agriculture."

The study:
Hüdig M et al (2022). Genome editing in crop plant research—Alignment of expectations and current developments. Plants 11(2). https://www.mdpi.com/2223-7747/11/2/212/htm

Image of drought by Viktor Pinchuk, licensed under the Creative Commons Attribution-Share Alike 4.0 International licence. Via Wiki Commons.