Genetic and Environmental Variation in Health-Promotingl-Homoarginine and Neurotoxic β-ODAP in Grass Pea(Lathyrus sativus L.)

Grass pea (Lathyrus sativus L.) is a promising legume crop due to its resilience to climatic stress factors such as drought and water-logging. However, the occurrence of the neurotoxin β-N-oxalyl-l- α,β-diaminopropionic acid (β- ODAP) and the lack of adaptedvarieties pose significant challenges for its wider adoption across Europe. On the other hand, the presence of l-homoarginine(l-hArg) in grass pea has gained attention for its benefits on cardiovascular health. In this study, contrasting grass pea genotypeswere grown at three locations in Germany, and the concentrations of α-, β- ODAP, l-hArg, and 17 other free amino acids wereanalyzed using liquid chromatography–tandem mass spectrometry (LC–MS/MS). β- ODAP concentrations ranged from 0.06%DW to 0.44% DW, whereas l-hArg concentrations varied from 0.16% DW to 0.90% DW. Concentrations of β- ODAP and l-hArgshowed a positive correlation (r = 0.40, p < 0.01). Glutamic acid was identified as the most abundant free amino acid, followed byarginine, aspartic acid, and alanine. Genotypes with mean β- ODAP concentrations below 0.15% DW were identified as suitablefor cultivation and food processing. β- ODAP and l-hArg were significantly influenced by the environment, whereas the geno-type significantly affected l-hArg concentration. The location with the lowest amount of rainfall during the flowering periodexhibited the highest β- ODAP concentrations. For the first time, we identified genotypes and environmental conditions withpositive health-promoting and low neurotoxin attributes under Central European conditions.