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Debate: The future of biosafety research

“Problems can occur even with conventionally bred plants.”

Bernd Müller-Röber

Prof. Dr. Bernd Müller-Röber is a biologist who is in charge of two research groups at the University of Potsdam and at the Max Planck Institute of Molecular Plant Physiology in Potsdam-Golm. His main areas of research include plant genome research and growth processes and gene regulation in plants. Among other things, he is Vice-Chairman of the BioEconomyCouncil and Spokesman for the Genetic Engineering working group of the Berlin-Brandenburg Academy of Sciences.

GMO Safety: In your view, what will be the main challenges for plant breeding over the next ten years?

Bernd Müller-Röber: We have biological questions that are in urgent need of research, and we also have technological developments. Something that continues to be very important, of course, is the issue of stress tolerance, both biotic and abiotic. We are seeing now that the environment is changing, and even if it is only slight changes in temperature, this can have significant effects on plant yields and on their susceptibility to pathogens. The search for genes that confer stress tolerance, and the breeding of these plants will continue to play an important role and may even become more important. The second area that has not yet been sufficiently well researched is how the carbon dioxide taken in by the plant is distributed to the growing plant parts, in other words, how the plant regulates the production of seeds as compared to roots, as compared to leaves as compared to fruit. The issue of optimising photosynthesis, i.e. the conversion of C3 plants into C4 plants, also belongs here. There are, for instance, projects where this is being attempted with rice, which is of course very visionary, but the next few years are bound to provide important information that gives us a better understanding of molecular regulatory mechanisms relating to C4 photosynthesis.

The third area is technical improvements, including technical improvements of plants. At the moment it is difficult to tell how far we can go with this. The problem with producing bioethanol from straw, wood waste or grasses is that you first need to decompose the plant cell walls. There are a number of different approaches here: either improving the decomposition process using chemical/physical or biotechnology methods, i.e. micro-organisms or enzymes, or modifying the plant. We will probably have to try both if we want to make progress in this area.

Efficient uptake and utilisation of nutrients will continue to be an important topic because there are still a lot of unanswered questions in this area. And finally, plant epigenetics, about which we understand very little at present, particularly in relation to crop plants. So far, we know that epigenetic processes in connection with flowering behaviour play a very important role, and flowering behaviour is of course vital for seed yield. There is now research that indicates that plant reactions to environmental stress are regulated to some extent by means of epigenetic processes, but we still understand very little about it.

All the aspects I have mentioned require a systematic understanding of how proteins, genes and metabolites interact. Plant system biology will, I believe, have an important role to play.

GMO Safety: Let’s take a concrete example: drought tolerance. How should one approach this aim from a plant-breeding perspective?

Bernd Müller-Röber: Drought tolerance is a complex phenomenon. A plant has different growth phases and they differ in their susceptibility to drought. We need to understand this in greater detail first, and then we need to try to identify the genes involved using new technologies, like ultra-fast sequencing.

In order to detect a causal relationship between the presence of a gene or gene variant and a change in the drought tolerance trait, we need to carry out functional studies, i.e. we need to produce lots of transgenic plants or lots of hybrids, and characterise them both physiologically and in terms of their molecular and biochemical changes.

Genes or gene variants that confer improved drought tolerance could then be inserted into crop plants using either marker-assisted selection or genetic engineering methods. However, drought tolerance is, as I said, a complex phenomenon. It is even doubtful whether modifying a single gene will be enough in this instance. We will probably have to carry out multiple modifications and take a close look at how the genes are regulated and when we should activate them in the plant and when we should silence them.

GMO Safety: Will plants with the new traits you mention pose new biosafety problems? And can classically bred plants cause biosafety problems too?

Bernd Müller-Röber: Breeding plants with different traits is a very old phenomenon. It is because of it that we have such diversity in our crop plants today. Breeding drought-tolerant plants is not a new area of work either. Triticale is a well-known example, where two complete genomes were practically fused to produce plants that are more drought-tolerant than the parent plants. This plant is being grown in increasing numbers around the world without anyone asking how safe it is. The fact that people are now using molecular techniques to discover gene variants with traits relevant for crop plants, and are using these gene variants in plant breeding does not, in my view, pose any fundamentally new problems for biosafety research.

If genetic engineering methods are used in this domain, we have the same questions as before: Where does the gene come from? Does it come from the plant or from another organism? What do we know about the protein coded by this gene? Is it a protein that is well documented or one that we know nothing about?

Of course, we always have to ask the question of how much the ecosystem will be disrupted or harmed, perhaps because a plant with a new trait has wild crossing partners that will in turn acquire a local advantage within the ecosystem. However, this is not related to the new breeding methods – it is a problem that has always been there: What happens when we release plants with different agronomic traits?

We need to carry out evaluations of conventionally bred plants as well because problems can occur with them too. One well-known phenomenon is that of invasive plants brought in from other continents. This shows that it is possible to generate problems without the involvement of genetic engineering or new breeding methods. But we should not make too much of this either. There are figures from the UK showing how many plants have been brought into the country over the past few centuries. It was around five thousand plant species, but of these, probably only ten actually caused a problem with economic or ecological impacts. This is something you cannot rule out entirely with new plants either, however they have been bred. An element of risk will always remain.

GMO Safety: What are your expectations of future biosafety research on genetically modified plants?

Bernd Müller-Röber: Until now, transgenic plants have carried one or two new genes conferring a specific trait. In future, there will be combinations of several different genes: one gene might make the plant resistant to chewing insects, the next might make it able to tolerate higher temperatures, the third might modify the lignin composition of the cell wall and the fourth might improve the plant’s nutrient uptake. We need to consider whether this development will result in new questions for biosafety research.

GMO Safety: Thank you for talking to us.

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