Acrylamide is a processing contaminant and Group 2a carcinogen which was discovered in foodstuffs in 2002. Wheat, rye and potato products are major sources of dietary acrylamide, with biscuits, breakfast cereals, bread (particularly toasted), crispbread, batter, cakes, pies, crispbread, French fries, chips and snack products all affected. The European Commission recently revised its risk management measures for acrylamide in food, introducing new, lowered Benchmark Levels and compulsory mitigation measures that must be adopted by all food businesses. These regulations came into effect in April 2018. The Commission has also threatened the imposition of Maximum Levels; i.e. levels above which it would be illegal to sell a food product. Acrylamide forms from free (non-protein) asparagine and reducing sugars (glucose, fructose and maltose), and the concentrations of these metabolites are affected by genetic (G) and environmental (E) factors, and G × E interactions. The free asparagine concentration of wheat grain, for example, is very sensitive to crop management, and sulphur deficiency, excessive nitrogen application and poor disease control must be avoided. Varieties of wheat, rye and potato have been identified with consistently low free asparagine concentration in the grain under good growing conditions, but the wheat varietal rankings break down under low sulphur conditions or in response to pathogen infection. We have used genetic, biochemical and RNA-seq analyses, together with mathematical modelling, to identify the genes that affect asparagine synthesis, accumulation and turnover in wheat. We have characterised the asparagine synthetase (TaASN) gene family and are targeting the TaASN2 gene, which is highly expressed specifically in the grain, using CRISPR/Cas9. A range of editing events are being characterised by NGS. We have also identified TaASN2 mutations in lines from a mutant wheat population produced by chemical mutagenesis.

Reducing the acrylamide-forming potential of wheat, rye, and potato: From crop management to variety selection and genome editing

2019 Fall National Meeting

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