October 27, 2020

Genetic editing and food for the future


Agriculture in this century faces a historical challenge: producing enough food for a population that in 2050 will be 9.7 billion. According to the FAO High Level Expert Forum, this means increasing agronomic production by 70% -100% in the next thirty years. However, the uncertainties brought by climate change suggest an opposite trend. Increasing temperatures and changes in rainfall regimes will cause yields to decline in the coming decades, weeds and pests to proliferate, and the area of ​​arable land to shrink. Furthermore, agriculture is a considerable source of CO2 that should be limited. In August 2019, the Intergovernmental Group of Experts on Climate Change published a report urging countries to (among other actions) encourage the cultivation of more productive plant varieties that are better adapted to increasingly unpredictable climates and soils. poor or salty. This would also reduce CO2 emissions by gigatons and free millions of hectares for forests, which fix CO2.

There is an urgent need to improve cultivated varieties in order to increase production, making the most of the soil and reducing the use of pesticides and fertilizers; develop plants with stable yields, resistant to pests and environmental stress. It is also desirable to generate biofortified foods that help prevent disease and supply nutritional deficiencies, and eliminate other allergens and unwanted compounds. But, with so little time, all this is an impossible task with current plant breeding techniques.

Traditional vegetable improvement falls short

Conventional plant breeding is based on producing random genetic mutations by irradiating millions of specimens, thereby inducing changes in their DNA and then selecting those individuals with useful mutations. Another approach is to make crosses with nearby species that have traits of interest, and try to fix them in the following generations without losing the advantages of the original line. These approaches have greatly increased productivity in recent decades, but it has been to the detriment of genetic diversity and with the loss of other interesting characteristics, such as the taste of tomatoes. In addition, they are very expensive processes and require very long deadlines. For this reason, they have increasingly concentrated on a few multinational seed companies.

Fortunately, a revolutionary technology, gene editing, has been developed in the last decade, which will allow to produce new vegetable varieties in a spectacularly fast, cheap and simple way. The resulting plants will not carry foreign DNA and therefore will not be transgenic, and will be indistinguishable from those obtained by traditional breeding. Unlike mutagenesis, gene editing only causes a few targeted genetic changes. Since it does not require selection, it does not reduce genetic diversity. In addition, it allows to improve many traits simultaneously and in a few generations, unlike traditional programs that require tens of years to improve a single character. All of these techniques are called NPBT (New Plant Breeding Techniques, or new plant improvement techniques), and are the future of agriculture.

The CRISPR revolution and gene editing

Gene editing uses the natural DNA repair machinery of organisms. The most popular tool today is based on CRISPR, a term coined in 2001 by Francisco Mojica, a researcher at the University of Alicante. CRISPR is an immune system that allows bacteria to recognize and destroy the DNA of hostile organisms. That is, they are “scissors” that precisely cut DNA by the desired genes. The system was adapted from 2012 as an editing tool by Jennifer Doudna (University of California), Emmanuelle Charpentier (University of Vienna), and Feng Zhang (Broad Institute, Harvard).

To use gene editing we have to know which genes have to be “corrected”. Thanks to basic research we know many of the genes that control interesting traits for agriculture, such as flowering time, fruit size, resistance to pathogens, cold, drought, etc. We also know which versions of these genes would have the desired effect. In many cases, turning off a single gene is enough to get a big improvement. For example, disabling the tomato MULTIFLORA gene results in plants having ten times more flowers and fruit.

Gene editing in laboratories and in the field

Hundreds of studies have described gene editing experiments on dozens of production species, and the results have been spectacular. In 2014, the Gao (Chinese Academy of Sciences) group generated wheat resistant to powdery mildew, a fungus that can destroy entire crops. In 2017, Francisco Barro’s group, from the IAS-CSIC in Córdoba, developed wheat lines with a very low gluten content, inactivating 35 of the 45 a-gliadin genes. None of these results would have been possible due to traditional improvement in so few years.

Some of the edited lines have already been approved in some countries and have made the leap to commercial production. Calyxt, an American company, markets soybean oil without trans fats and with 80% oleic acid. Mushrooms that won’t blacken when cut will be on the market soon. The Corteva company has produced a type of corn identical to another that is used to make thickeners.

But NPBTs are not going to be left to big companies. Its simplicity and low cost represent a true revolution and democratization of improvement. Small seed companies are already developing independently or in collaboration with research groups on-demand improvements to their own local varieties.

The recovery of genetic diversity

An exciting perspective on gene editing is the possibility of recovering the genetic diversity of wild species, lost after centuries of selection. For example, almost 5,000 genes have been lost during the domestication of tomatoes, including some that provided flavor and resistance to disease. The researcher Pereira Peres from the University of São Paulo carried out a de novo domestication of the wild tomato progenitor, Solanum pimpinellifolium. This species produces few berries, very small, but with very high levels of lycopene, a powerful antioxidant with high nutritional value. His group edited six genes in the wild and in one generation obtained plants with 10 times as many tomatoes, similar in size to domesticated ones, and with five times more lycopene than commercial tomatoes.

There are at least 20,000 edible species that have never been domesticated, many of which have beneficial nutrients and are more resistant to disease and extreme climates. Its domestication by gene editing opens up immense possibilities for the development of new foods with more sustainable production.

Europe may lag behind

Countries around the world are betting heavily on NPBTs. In the United States, the Department of Agriculture does not require labeling “edited” foods since they do not contain foreign DNA fragments and cannot be distinguished from traditional ones. Australia is not going to regulate them because NPBTs generate mutations “more precisely than traditional techniques.” In Japan a panel of experts has declared these products safe for consumption and recommends not to regulate them. China has made a million dollar investment in research in NPBT, and holds the largest number of publications and patents in the world in this field. Russia has just invested $ 1.7 billion to edit, in eight years, 10 agronomic species including barley, beets, wheat and potatoes.

Meanwhile, the European Court of Justice ruled in 2018 that any variety produced using NPBT is subject to the regulations of Genetically Modified Organisms (GMOs). According to European legislation, any variety generated “by altering its genetic material in a way that does not occur naturally” is considered a GMO.

Paradoxically, the mutagenesis of classical enhancement (not natural at all and equivalent to gene editing but much less precise) is specifically excluded from the standard, due to its traditional use and proven safety. This situation leaves European farmers and companies at a clear disadvantage compared to countries and multinational companies that in a short time will be generating and exporting more productive and resistant edited varieties, not labeled, and impossible to trace because they do not contain foreign DNA.

Farmers, companies and scientific associations grouped together in the European Plant Science Organization have urged the European Union to review the legal framework to allow the use of NPBTs. This could become a reality by 2021 as the Council of the EU requested in November 2019 a study and a proposal from the European Commission to contemplate new measures in relation to gene editing.

With or without Europe, according to Jennifer Doudna, in the next five years we will be consuming genetically edited foods. The survival of the human species has always depended on advances in agriculture, but in this century the destiny of the planet will also depend on it.

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