β-n-oxalyl-l-α, β -diaminopropionic acid (β -odap) content in lathyrus sativus: The integration of nitrogen and sulfur metabolism through β -cyanoalanine synthase

Grass pea (Lathyrus sativus L.) is an important legume crop grown mainly in South Asia and Sub-Saharan Africa. This underutilized legume can withstand harsh environmental conditions including drought and flooding. During drought-induced famines, this protein-rich legume serves as a food source for poor farmers when other crops fail under harsh environmental conditions; however, its use is limited because of the presence of an endogenous neurotoxic nonprotein amino acid β -N-oxalyl-L- α, β -diaminopropionic acid (β -ODAP). Long-term consumption of Lathyrus and β -ODAP is linked to lathyrism, which is a degenerative motor neuron syndrome. Pharmacological studies indicate that nutritional deficiencies in methionine and cysteine may aggravate the neurotoxicity of β -ODAP. The biosynthetic pathway leading to the production of β -ODAP is poorly understood, but is linked to sulfur metabolism. To date, only a limited number of studies have been conducted in grass pea on the sulfur assimilatory enzymes and how these enzymes regulate the biosynthesis of β -ODAP. Here, we review the current knowledge on the role of sulfur metabolism in grass pea and its contribution to β -ODAP biosynthesis. Unraveling the fundamental steps and regulation of β -ODAP biosynthesis in grass pea will be vital for the development of improved varieties of this underutilized legume.