Cultivar- and field site-specific protein and metabolite patterns of faba bean ( Vicia faba L.) seeds

Sustainable agriculture is an important component of current and future food production, particularly in the face of the rising human world population. In this context, faba bean ( Vicia faba L.) is highly valuable due to its capability to enrich soils with nitrogen and because its seeds have a high nutritional value. In this study, we compared the seed chemistry of 11 faba bean cultivars grown at 13 field sites in Germany. Nitrogen and sulfur contents were determined with the Dumas method and protein contents were calculated based on the obtained nitrogen data. SDS-PAGE was used to analyze proteins, while metabolic fingerprinting was applied to screen (semi-)polar metabolites, mainly comprising specialized metabolites. The protein content differed predominantly between cultivars, but also between field sites. The sulfur content strongly depended on the field site. The patterns of proteins and metabolites were largely cultivar-specific. Additionally, the number of metabolic features varied somewhat between field sites. Our study suggests that breeding led to comprehensive changes in the seed chemistry of V. faba bean, going far beyond protein content and certain metabolites targeted in breeding. The rather high consistency when comparing field sites indicates that breeding has led to more or less stable cultivars. Future studies should place more emphasis on far-reaching effects of breeding on the seed proteome and metabolome of faba bean, as various proteins and metabolites in concert determine the nutritional quality of seeds of this important crop species.