Wheat contains many genes coding for proteins that are toxic to people with celiac disease (gliadins), but CRISPR could edit them all out. Researchers at the Institute for Sustainable Agriculture (Córdoba, Spain) have managed to knockout up to 35 of these genes, reducing immunoreactivity by up to 85%. The 100% goal now seems to be at hand. But is biotech “gluten-free” bread tasty? And is it going to reach the market? We asked plant scientist Francisco Barro, corresponding author of the paper recently published in Plant Biotechnology Journal.
Last year a feature in Nature Biotechnology discussed your work with RNA interference (RNAi). Why are you using CRISPR now?
It’s a versatile tool for genome engineering. Unlike RNAi, the CRISPR system allows the introduction of heritable and precise modifications in the eukaryotic genome. This new technology offers us the possibility of obtaining very specific changes without the need to introduce foreign DNA into the organism’s genome. In the case of gluten, although RNAi technology is totally safe, providing excellent results in the silencing of gluten proteins, CRISPR may have a better public perception. Both CRISPR and RNAi are highly effective for obtaining wheat lines lacking celiac disease epitopes. However, the main advantages of the CRISPR knockouts vs RNAi are that (i) CRISPR knockouts are stable and heritable mutations that do not involve the expression of a transgene, and (ii) therefore, they provide a phenotype that is independent of environmental conditions. In addition, CRISPR would allow different strategies to that reported in this work, that is cutting larger chromosome fragments containing gliadin genes, or even more, replacement of highly immunogenic fragments with others less toxic, keeping the gliadins functionality. In contrast, in order to have all gliadin genes mutated by CRISPR, subsequent rounds of mutagenizing will be needed using specific guide RNAs to target the remaining gliadin genes.
Let’s face it. Is there any foreign DNA left in your edited wheat?
As we reported in our Plant Biotechnology Journal paper, many lines showed a reduction of alpha-gliadins and were identified as transgene-free and insertion-free. In addition, we are working to generate new transgene-free material using this technology and editing other gluten proteins.
You were able to mutate 35 out of 45 gliadin genes. How far is real gluten-free wheat?
The fact that we have managed to mutate such a number of genes is already an unprecedented achievement that brings us closer to the possibility of obtaining gluten-free wheat. There is still a way to go in the study of this genetic editing technique, but with these results, the hope of getting a wheat suitable for celiac disease is much more real as we are working on mutating other important gluten genes also related with celiac disease.
Did anybody taste your low-gluten edited wheat? Are you planning any trial?
Not yet, the lines that we have produced are still in a very early experimental stage. We plan to continue working with these lines and with the gluten genes that have not been mutated in these lines. However, we have produced bread using the RNAi lines with a 95% lower gluten than the wild type, and sensory evaluation was comparable to that of the normal wheat containing gluten.
Some celiac organizations have already expressed their willingness to accept gluten-free GM wheat. Do you think that CRISPR could make regulators, farmers, millers, bakers, and consumers more comfortable?
The possibility of obtaining edited crops free of transgenes, inserts or foreign DNA will make things much easier in terms of social acceptance. Personally, I think that edited plants should not be regulated as GMOs as they are not the same. Edited crops have no foreign DNA, but their own genome has been accurately mutated. Chemical mutagens are widely accepted, I see no reason why CRISPR should not. Both transgenic and CRISPR are totally safe for food production. However, CRISPR could be better received than transgenic. In this way, perhaps CRISPR is the door for the transgenic plants to be accepted by society.