Research Live: Getting to the bottom of GMO detection methods

GMO-Testing Expert Discusses the Field’s Most Critical Questions

Co-Extra’s editorial office interviewed Dr. Guy Van den Eede, leader of a Co-Extra research project investigating GMO detection methods. Van den Eede is head of the Biotechnology and GMO unit of the European Commission Joint Research Centre’s Institute for Public Health and Consumer Protection in Ispra, Italy.

Why is it so important for the European Union to be investing in research on GMO testing?

Guy Van den Eede is head of the GMOs and Biotechnology Unit of the Institute for Health and Consumer Protection.

We need to address the fact that there are so few techniques that labs can use for GMO testing. The only reliable technique used today for quantitative GMO testing is quantitative PCR (polymerase chain reaction). But this technique has a lot of drawbacks. The error margin is often quite large, especially when you need to detect GMOs at very low quantities. European legislation requires us to detect at around 0.9 percent GM content, which makes for a rather high margin of error. A technique that is less cumbersome and more straightforward would be a great step forward for GMO testing labs.

A second major reason why research in GMO testing is important is the need to develop multiplex detection methods, which means detecting more than one GMO with just one test. Right now, GMO tests usually look for one GMO at a time. That means we need to check for GMO 1, 2, 3, 4, and so on. With the number of GMOs being grown today, this is becoming less and less feasible. We need to get a much better understanding of the commonalities between GMOs to make it easier for us to detect many GMOs at once.

A third point is that GMO testing is only done in laboratories. There would a be tremendous advantage if it could also be done on the spot, like in a field, at a harbour, or in a factory, and ideally using a high-throughput system. There is still a lot of work to be done. GMO detection is really only at the very beginning, and with all the new GMOs that are being marketed today, there is definitely a need for improved methods that are more efficient.

What’s the biggest need laboratories have when they are given a sample to test for GMOs?

PCR subjects a reaction mixture to cycles of heating and cooling using specialised equipment. In the past, enforcement laboratories didn't have the GMO testing protocols they needed. But with the new EU legislation on GMOs, companies are obliged to submit a test protocol for each GMO they want to place on the market. As soon as the protocols are validated, they're put on the internet and made public. What laboratories really need today is easy access to positive and negative control samples. Quantitative GMO tests need reference materials with varying percentages of GM content to compare with unknown samples. Reference materials are like the lines on a thermometer; without them you don’t know how to evaluate what you’re looking at. But different references are needed for every GMO that’s out there. Pre-made control samples are only available for a limited amount of them. It’s quite time consuming to prepare certified reference materials, which is the competence of our sister institute, the Joint Research Centre’s Institute for Reference Materials and Measurements in Geel, Belgium, which is the world leader in this field. It takes several months for them to come up with reference material for a new transgenic crop, leaving testing labs on their own to make reference material for many GMOs.

Dyed DNA samples were loaded into a gel matrix for electrophoresis. After the samples migrated across the gel in an electrical field, visible bands reveal the presence of a GMO.What does “percentage of GMOs” actually mean?

What the percentages actually stand for hasn’t always been clear. In the past, we’ve interpreted it as a weight/weight ratio, so for a one percent reference we would mix one gram of GM grain with 99 grams of conventional grain. But you could also view it as the percentage of individual kernels that are GM. In that case you would just take one individual GM kernel and mix it with 99 conventional kernels, regardless of the weight. Fortunately, there’s now a general consensus about how to define what the percentages mean. Rather than the weight, we’ve found the best way to do it is to go straight to the DNA. We mix one gene from a GMO together with 100 copies of a gene for that crop. This is important because instead of needing to painstakingly mix reference material and extract DNA, we just take DNA we make in the lab and mix it just how we need it. It takes much less effort and is actually much more precise.

How important is good sampling for getting accurate GMO test results?

Having proper sampling is absolutely essential. If your sample isn’t representative for the bulk that you want to analyse, all of the subsequent steps are meaningless. For instance, authorities in the USA and Canada have generally assumed that in a ship with 20,000 tonnes of soybean grain, the GM grains would be evenly mixed in. So if you just take a handful of grains back to the lab for testing, you would be very likely to get a representative sample. But we have always questioned this assumption, and we have carried out research within the European Network of GMO Laboratories (ENGL) in ten member states where we sampled soybean grains from incoming shipments. We found that the distribution of grains is in fact highly, highly uneven, which would call for much more elaborate sampling strategies. No matter how carefully you do the testing, analysing a sample that isn’t representative for the bulk will be of no use.

If improper sampling alone can invalidate test results, is it possible that stakeholders could simply dismiss results that they don’t like, citing their inherent uncertainty?

Adequate sampling is crucial: How large of a sample do you take back to the lab for testing? We have given some recommendations for proper sampling to address this issue. We prescribe the number of samples you need to take in various situations. If the test shows you’re far above or far below the threshold, a bit of uncertainty isn’t a big problem. But if you’re in the vicinity of the threshold, that’s when you get into the red area. In this case, we recommend taking additional samples. The more samples you take, the more confident you can be that the test results represent the bulk you’re testing.

You also have to think about what happens to the grain after it’s unloaded from a ship. Most of the shipment could be completely GMO free, and then a small area could be ten percent GM. You could do extensive sampling and find out the shipment exceeds the threshold for labelling. But that might not matter, because the first 50 truckloads could actually be completely GMO free. Therefore it’s not sufficient to only know at the harbour, but you should also check at very specific points throughout the entire food and feed processing chain.

Wouldn’t it be a better strategy to test the trucks leaving the harbour instead of the contents of the ship itself?

Cargo ship: Taking samples back to the lab can be done at many different points along the food supply chain. This all depends on who’s interested in the test results. If you were purchasing grain and wanted to know if it is or isn’t GM, you would only be concerned with the trucks that arrive at your company. Control agencies, however, would likely be concerned with the GM content of the entire ship in order to monitor the system. But from a consumer’s point of view, the only thing that matters is knowing if your package of flour contains GMOs, regardless of the composition of the original shipment. That’s why it all depends on who has stake in the goods at hand.

How likely is that a GMO could go through testing and come out completely undetected?

That can be problematic, because a test for a GMO is based on previous knowledge about that GMO. We know of the GMOs that are on the market worldwide and of those that are in the pipeline. You can design tests that will pick up all of those. And most GMOs are composed of common elements such as commonly used promoters and terminators. If there is a GMO that we don’t know about and that uses completely new components that have nothing in common with any other GMOs in the world, we might miss that one. The chances of this happening, however, aren’t realistic. There is a very high probability that we’ll find it.

What type of progress has been made so far with the research that you’re overseeing?

The research for Co-Extra that I’m overseeing is still in its early stages. Nonetheless, we’ve already been able to agree on the points in the production chain that are best for testing, and we’ve been able to support this with evidence. All of our data will be coming out in the next months and the next year. I’m very much looking forward to our next meetings when real results will be presented and discussed.