Seed World

GM Crops Have Reached Knowledge Limit


Genetic Modification of plants will be essential to avert future food shortages, but crop scientists will need to build a much better understanding of fundamental plant processes first.

An international group of agricultural scientists, from Rothamsted Research in the UK and from Syngenta Crop Science and Symmetry Bioanalytics in the US, have reviewed how biotechnology has shaped the efficiency of crop production over the past 35 years, and concluded that, while GM has been of great benefit, it is now being limited by the boundaries of plant science.

While modified crops able to repel insect pests or to resist herbicides have transformed the farming of soybean, cotton, maize and canola by reducing costs and increasing productivity, further improvements in yield, particularly in testing climatic conditions, depend on more in-depth research.

The transatlantic team, which presented its review as an online opinion article in Trends in Plant Science, noted that while scientists have identified some genes that affect crop yields, such as those influencing grain size and leaf growth, they have still to fully understand the cellular and developmental processes, and how these processes behave in a field environment.

“Our knowledge of the genes that limit yield in field conditions needs to be developed,” says Rothamsted plant biochemist Dr. Matthew Paul, who led the review team. “At the moment, results that show promise in the lab don’t always work in the field.

“We are emphasizing the great potential of GM, and of genome editing and emerging chemical technologies as well, but in a sense the potential of the technologies on offer is running ahead of our ability to deploy them because we still don’t know enough about the many processes and genes that determine yields.”

Dr. Paul highlighted how GM research at Rothamsted had identified a sugar, trehalose 6-phosphate (T6P), that controls the volume of starch in cereal grain and, in GM field trials, substantially improved maize yields in the field, from 10 percent in well-watered crops to 120 percent under drought conditions.

“But we got there only because field trialing was conducted in parallel with fundamental science of which genes to target and how to target them in the field environment,” he explains. Subsequent collaboration with chemists at the University of Oxford led to the pioneering development of a chemical method to alter T6P that, if commercially successful, would enable farmers to spray an enhancer onto crops to increase grain yield.

As the review notes, in the case of trehalose signalling, fundamental science had run alongside field evaluations to deliver yield improvements based on a strong element of understanding mechanisms, and such a strategy would be necessary, adds Dr. Paul, if GM and future genome editing approaches and chemical technologies were to “deliver on their promise of step changes in yield” in a range of environments.