Faba bean ‘potential unlocked’ after scientists identify gene behind often-fatal hereditary disorder

Faba beans (also called broad beans) are an excellent source of food protein at a time the industry is desperate to find new alternative proteins to improve the flavour, texture and appearance of the current crop of plant-based products and meat alternatives.

Among legumes – the pod-producing family of plants to which pea, chickpea and soybean also belong – faba beans have the second-highest yield globally. They also have the highest seed protein content of the starch-containing legumes and out-perform soybean in cool climates.

But about 4% of the world’s population have favism, a genetic disorder involving an allergic-like and potentially fatal reaction to faba bean consumption. Favism produces acute hemolytic anemia and can be triggered by walking through a field where there are faba beans. Symptoms can include acute back and abdominal pain, jaundice, headache, vomiting, nausea and a raised temperature.

The condition can be particularly dangerous if faba is included, unknown to the sufferer, in flours, bread mixes, and bakery products.

Favism is more common in warmer southern regions and has given broad beans a bad name since ancient times. Pythagoras and his followers avoided them, and Roman priests of Jupiter associated them with death.

However, it may now be possible to grow faba beans that won’t cause a reaction after a team of scientists from Denmark, Finland, Germany, the UK and Canada identified the gene (the VC1 gene) responsible for the production those compounds present in faba beans (in this the case, anti-nutrients called vicine and convicine) which renders them sensitive to favism sufferers.  

The work, published in Nature Plants​, ultimately paves the way for breeding, production and commercial use of faba bean varieties totally free from these anti-nutritional compounds, the researchers claimed.

Fernando Geu-Flores, Associate Professor and Research Group Leader at the Section for Plant Biochemistry and Copenhagen Plant Science Centre, who led the work, said favism up to now has inevitably limited the potential use of faba bean: “Now that we understand where these anti-nutrients come from, we can attempt to breed them out completely, thus contributing to food safety and sustainability,” ​he said. “​Now that we have a good handle on the biochemistry behind vicine production, we can ourselves use new breeding technologies to attempt to generate varieties that are completely free of vicine, thus eliminating any worries about favism.”​

Stig U. Andersen, Associate Professor of the Department of Molecular Biology and Genetics at Aarhus University in Denmark, told FoodNavigator: “The problem with vicine and convicine is that they elicit oxidative damage in people with a specific enzymatic defect, Glucose-6-phosphate dehydrogenase deficiency. With the identification of the VC1 gene, we now have a good idea about the genes involved in the rest of the biosynthetic pathway as well. Targeting additional genes in the same pathway is what will hopefully allow complete elimination of vicine of convicine in future faba bean varieties… faba beans without vicine and convicine will be complete safe for people with favism.”​

These future varieties will have the same appearance as conventional faba beans. But because anti-nutrients are being removed “we expect the flavour and nutritional value to be improved”, ​said Andersen. “Vicine and convicine may contribute to bitter flavour, which would be reduced on elimination.” ​

Reference

VC1 catalyses a key step in the biosynthesis of vicine in faba bean​

Nature Plants​

Authors: Emilie Björnsdotter, Marcin Nadzieja, Wei Chang, Leandro Escobar-Herrera, Davide Mancinotti, Deepti Angra, Xinxing Xia, Rebecca Tacke, Hamid Khazaei, Christoph Crocoll, Albert Vandenberg, Wolfgang Link, Frederick L. Stoddard, Donal M. O’Sullivan, Jens Stougaard, Alan H. Schulman, Stig U. Andersen, and Fernando Geu-Flores

DOI: https://doi.org/10.1038/s41477-021-00950-w​.

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