Integrated GWAS and metabolomic analyses identified metabolic pathways and candidate genes involved in free asparagine accumulation in durum wheat grain

Free asparagine content is a key factor in acrylamide formation in wheat products after high temperature processing. Our study aims to explore free asparagine natural variation in durum wheat to identify genes potentially involved in this trait. Two hundred and one durum wheat genotypes were sown in an experimental field for three years. An enzymatic assay was used on whole grain to evaluate free asparagine content, that ranged from 0.9 to 4.73 mmol/kg dry matter. A genome-wide association study (GWAS) identified six associated SNPs on chromosomes 6A, 7A, 2B, 4B, 7B. The whole grain metabolome of one-year samples revealed 40 metabolites, correlating with asparagine variations, that were enriched in pathways involved in amino acids metabolism. Combining GWAS and metabolomic data identified two L-lactate dehydrogenases, one polyamine oxidase, and one anthranilate-phosphoribosyl-transferase as candidate genes. This study paves the way to characterize the genetic determinants of free asparagine accumulation in wheat grain.