Genetic engineering 2.0: old problems, new tools

genetic engineering 2.0: old problems, new tools

Rapeseed field. Image: bernd schroder

Genome editors aim to make plant breeding faster and more accurate – and increase customer acceptance. Part 2

Cibus: "globally acceptable, non-transgenic traits for all major crops"

Large agribusiness companies are currently exploring the possibilities of new genome editing technologies in plant breeding, and biotech start-ups are also looking for their share of the pie. How, for example, cibus. Su canola, a canola variety tolerant to sulfonylurea herbicides, had been applied to fields in north dakota and montana in 2016. The potential is immense: canola is grown on about nine million hectares in north america, and the trend is rising.

Part 1: our small crispr farm

In addition, non-transgenic cibus flax, which is tolerant to glyphosate, is to be introduced to the fields in the future. The development has been sponsored in part by the flax council of canada, which hopes to provide effective weed control. A rice variety also under development is to be made tolerant to two different herbicides.

genetic engineering 2.0: old problems, new tools

Rtds from cibus makes use of cellular dna repair mechanisms. Image: cibus

The rtds (rapid trait development system) developed at cibus is based on oligonucleotide-directed mutagenesis (odm). In odm, short dna molecules – oligonucleotides – synthesized in the laboratory are introduced into the cell in order to trigger targeted mutations at a specific point in the genome. They carry the complementary sequence of a specific site of the target plant’s genome to which they can dock. The sequence also contains a deliberately inserted error, which is taken over by the plant into its own gene. The mutation thus forced may be an exchange of single or a few nucleotide pairs, a deletion, or even an insertion of short fragments of cellular dna.

The inserted oligonucleotides do not represent new combinations of genetic material, their sequence depends on the target sequence. They mediate the modification of the genetic material, but are not themselves integrated into the genome of the plant and degraded – they only stay temporarily in the plant cell. For proponents, the process is equivalent to traditional mutagenesis techniques and therefore, in their view, does not require regulation. This is because it is not possible to determine afterwards how the mutation came into the genome – an argument that is also put forward by representatives of other genome editors and which constructs a justified equivalency to the established breeding methods that are regarded as safe. The objection may be factually correct at the moment, but with the rapid development in molecular biology, it will only have a short-lived validity. Promising work is already being done on suitable analytical tools.

The non-transgenic character of the fruits of the technology is also repeatedly emphasized at cibus; in addition, the method offers further advantages over other methods. Thus one hopes for a broad acceptance of the product range. The corporate view is that a living thing can only be called a genetically modified organism (gmo) if foreign dna has been introduced – one of the main arguments of those who want to see new genome editing tools unregulated. Consequently, cibus products could not be declared as gmos. As a result, the company does not feel threatened by market rejection, nor does it feel affected by the legal requirements that are typical for gmos.

Cibus had tried to circumvent the european opinion-forming process on the new technologies by presenting legislators with a fait accompli: decisions by individual member states on the new technologies, as well as persuading them to conduct early field trials. At least six eu member states were contacted by cibus. Observers suspect that this was intended to trigger different reactions between different eu members, ultimately driving a wedge into the notorious rejection on the continent.

Cibus also knocked on germany’s door. In 2014, the company asked the german federal office of consumer protection and food safety (bvl) whether cibus’ developed herbicide-tolerant canola would be classified as a gmo. In an initial communication, cibus was informed that the evaluation "do not include participation or active information of the public or involvement of other authorities" was. Bvl ruled that cibus oilseed rape should not be classified as a gmo under genetic engineering legislation. The german federal agency for nature conservation (bfn) had come to the opposite conclusion.

In the absence of a directive providing clarity on the use of the new technologies, the german government decided in spring 2015 that cibus’ oilseed rape seeds were not gmos and field trials could begin. Soon mail arrived from the eu commission, with the request to wait for the legal interpretation. Because the deliberate and unauthorized release of plants subject to eu gmo legislation is illegal. Since then, a statement from the eu commission on the legal status of the plants has been awaited. Interest groups call for an overhaul of the legislation in europe, which is no longer up to date in view of the modern technologies of genome editing.

Cibus, for its part, informed the commission that the plants had already been grown in the u.S. – as normal crops that could therefore be expected to appear in the international commodity chain, including in the eu.

A coalition of 45 german ngos finally took the bvl decision to court. In july 2015, the bvl informed the commission that the field trials had been suspended for the time being.

Potato: complex genome complicates breeding of disease-resistant varieties

Finally, towards the end of the current decade, a cibus potato is also expected to be resistant to potato powdery mildew (phythophthora infestans), which can cause late blight in potatoes and lead to drastic crop failures – like during the great famine in ireland. It began in 1845, shortly after the pathogen had been introduced into europe from the usa. One million people fell victim to the "gross hunger" but the deaths were not solely due to potato powdery mildew. At that time, politicians had come to the conclusion that the state should stay out of economic matters as much as possible, and the rulers did not deviate from this, even during the crisis. As a result, while many people starved to death, large quantities of food continued to be exported.

There were also repeated potato crop failures in other parts of europe. In the rainy autumn of 1916, for example, potato powdery mildew destroyed part of the german potato crop, which ended up at half the previous year’s yield and led to the cabbage winter of 1916/1917. The copper compounds used to combat the disease were lacking due to the war. The fungicidal effect of synthetic dithiocarbamates was discovered 20 years later.

The potato continues to be an important crop, with around 5.000 varieties known. In 2013, 54 million tons were produced on 1.74 million hectares in europe alone (world production: 376 million tons on 19.3 million hectares, as of 2013): potatoes for consumption, as seed, for starch production and as animal feed. Potato powdery mildew is estimated to cause annual economic damage throughout europe in the form of crop losses and extra costs amounting to one billion euros. Efforts to tackle the problem have therefore been underway in europe for a long time, and genome editors are now being brought in to help.

The potato genome is considered to be particularly complex. Most varieties are tetraploid, i.E. They have four complete sets of chromosomes. Targeted breeding of phythophthora-resistant varieties is hampered by the potato’s difficult genetics. The potato genome had been deciphered in 2011: scientists had sequenced 86% of the 844 million base pairs of potato dna. Various resistant varieties have already been developed through conventional plant breeding, but resistance to the tuber blight pathogen comes at the price of compromising other characteristics: taste, shape, color and processability. Genome editing is now expected to simplify targeted genetic improvement and produce results much faster than before.

Genetic engineering 2.0: old problems, new tools

Potato. Image: amedee masclef – atlas des plantes de france, 1891, in the public domain

Potato powdery mildew has very adaptable genetics. It overcomes surprisingly quickly the mechanisms of action of synthetic fungicides and breaks through the natural resistance mechanisms crossed into potatoes by traditional breeding. Many years of work on promising crosses, such as the bionica and toluca varieties, thus offer only a few years of protection against the disease. Other potatoes, such as the hungarian sarpo mira with at least five resistance genes, can effectively resist potato powdery mildew, but they are considered to have poor culinary qualities. Sarpo mira was still commissioned by the soviet union as a robust variety that could handle harsh climates and diseases and thrive without expensive pesticide inputs. Its development lasted more than 40 years.

Its enormous spore production and rapid multiplication exacerbate the problem of potato powdery mildew: up to 20 generations can succeed each other per season. Unsuccessful breeding attempts of resistant species and the development of synthetic pesticides shifted the focus of potato powdery mildew control to chemistry. Europe’s farmers are now fighting back with massive fungicide use. 10-15 normal sprouts can quickly become 25 in humid summers.

In with the potatoes, out with the potatoes

Genetic manipulation has been practiced on the potato for more than 20 years. In 1995, monsanto introduced the transgenic newleaf potato, the company’s first genetically modified crop. It should resist the attacks of the potato kafer. For this purpose, genes from the bacterium bacillus thuringiensis were inserted to produce the bt toxin. However, the insect-resistant potatoes found only a small market. In 2001, monsanto stopped the sale of newleaf seed.

The rejection of transgenic potatoes by the market has slowed down the development of new traits in the recent past. One example: basf plant science’s amflora potato. It should be established as a renewable raw material for starch production. For this purpose, the formation of amylose in the potato was switched off, which from now on produced only amylopectin, which is more in demand in some industries. The court of the european union withdrew the order in 2013.

Due to the lack of acceptance in europe, basf plant science had already discontinued its biotechnology projects designed for the european market in 2012 and relocated to north america. This also meant the end of the newly developed fortuna variety. It was based on a south american wild potato resistant to phythophthora infestans, in which several genes responsible for resistance had been identified and two of them incorporated into fortuna. The aim was to reduce farmers’ use of fungicides, which is particularly important in potato production in poor weather conditions.

"Pandora’s potatoes"

In the usa, the development of j.R. Simplot company, a leading u.S. Agribusiness that supplies potatoes to fast-food chains and others – in 2005, for example, it was responsible for more than half of all the french fries that crossed the counter at mcdonald’s.

As of february 2017, the russet burbank, ranger russet, and atlantic varieties of the innate generation 2 product line had successfully undergone all the necessary procedures for approval. The company advertises beneficial characteristics for growers, such as fewer gray-brown bruises and reduced black spot, lower asparagine content, protection from the tuber rot pathogen, and improved cow storability. With phythophthora resistance, savings in fungicide use are said to be between 25-45%.

A promise of the first-generation innate potatoes, which already have the same installed characteristics as their second-generation innate successors except for phythophthora resistance and optimized storability in the cold store, had made headlines when they were introduced. The lower concentrations of the amino acid asparagine and certain reducing sugars should reduce the formation of harmful acrylamides by 90% or more during treatment at higher temperatures, such as those encountered during frying. The metabolic pathways of the potato involved in this process were manipulated by switching off the enzymes involved via rna interference (rnai).

But controversy surrounding gm foods is also growing in north america, despite the newly incorporated, customer-friendly features and the emphasized distance from transgenic genetic engineering: food water watch, a washington ngo, had challenged mcdonald’s with a "no mcfrankenfries for me"-petition calling on mcdonald’s not to offer the innate potatoes, which the fast food chain agreed to. And although innate potatoes are already being sold in 4,000 supermarkets in 40 u.S. States, interest in the new biotech tubers is limited. So far, there have been additions in canada and japan, in china, malaysia, mexico, singapore, south korea, taiwan and in the philippines it is being considered.

In october 2018, one of the creators of innate potatoes surprisingly spoke out in book form. Caius rommens, former head of biotech research at j.R. Simplot, takes a hard look at himself and his work. For years he believed that his theoretical knowledge of potatoes would enable him to improve them. Today, he is convinced that this was one of his gross errors.

The netherlands: the national durph potato

In 2005, the dutch government, fearing that it would be robbed of its competitive edge, decided to provide financial support for the development of a national, genetically engineered potato. While the potato industry refused to invest in the durph (durable resistance to phythophthora) project, the development of a cisgenic potato resistant to the tuber blight pathogen was fully funded by public money. Ten million euros went to wageningen university, with a tenth of the budget reserved for accompanying communications, as opposition was expected from the outset.

Additional obstacle for potential sponsors: the unclear attitude of eu legislators. Classification as a gmo technology would mean the commercial end of the new potato in europe. Therefore, keeping cisgenesis out of gmo legislation was a top priority for the dutch government. But in the summer of 2015 came the end – the industry could not be persuaded to invest in a continuation of the project. However, in the case of a derogation for cisgenesis in the eu, this would quickly change.

Contribution in the fight against world hunger? Usaid potatoes for bangladesh

In late 2016, the bangladesh agricultural research institute (bari) applied for commercialization of a phythophthora-resistant potato. The breeders involved had been working on the potato since 2006. The resistance gene comes from wild varieties that were incorporated into the katahdin variety in the u.S. This in turn was crossed with the diamant and cardinal varieties popular in bangladesh.

genetic engineering 2.0: old problems, new tools

World hunger map 2018. 821 million earthlings do not have enough to eat. The number of hungry people worldwide is on the rise again. Image: united nations world food program

The potato was developed in a bari collaboration with the agricultural biotechnology support project ii, a consortium of public and private institutions sponsored by the united states agency for international development usaid. As recently as 2015, usaid awarded a $5.8 million cooperative agreement to michigan state university to develop a phythophthora-resistant potato for bangladesh and indonesia. Grant supports usaid’s work under feed the future, the u.S. Government’s global hunger and food security initiative. Also on board: simplot.

Bangladesh produces nine million tons of the tubers annually, and a large proportion is exported. The country is the seventh-largest potato producer in the world, right after germany. After the ministry of agriculture forwarded the application to the relevant biosafety committee and the national biosafety agency gave the go-ahead, the new potato became the second gmo crop grown commercially for food in south asia, following the introduction of transgenic eggplant bt brinjal in 2013.

Meanwhile, neighbor india is preparing to cultivate its first crop genetically modified for food production: mustard. Transgenic cotton was approved as early as 2002. Once through the approval process, the higher-yielding gmo variety is expected to produce bigger harvests and alleviate import dependence in the crop oil sector – a goal that observers doubt is sincere.

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