Genetic and Environmental Variation in Health‐Promoting <scp>l</scp> ‐Homoarginine and Neurotoxic β‐ODAP in Grass Pea ( <scp> <i>Lathyrus sativus</i> </scp> L.)

ABSTRACT Grass pea ( Lathyrus sativus L.) is a promising legume crop due to its resilience to climatic stress factors such as drought and waterlogging. However, the occurrence of the neurotoxin β‐ N ‐oxalyl‐ l ‐α,β‐diaminopropionic acid (β‐ODAP) and the lack of adapted varieties 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 genotypes were grown at three locations in Germany, and the concentrations of α‐, β‐ODAP, l ‐hArg, and 17 other free amino acids were analyzed 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 ‐hArg showed a positive correlation ( r = 0.40, p &lt; 0.01). Glutamic acid was identified as the most abundant free amino acid, followed by arginine, aspartic acid, and alanine. Genotypes with mean β‐ODAP concentrations below 0.15% DW were identified as suitable for cultivation and food processing. β‐ODAP and l ‐hArg were significantly influenced by the environment, whereas the genotype significantly affected l ‐hArg concentration. The location with the lowest amount of rainfall during the flowering period exhibited the highest β‐ODAP concentrations. For the first time, we identified genotypes and environmental conditions with positive health‐promoting and low neurotoxin attributes under Central European conditions.