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Title: ß-N-oxalyl-L-a,ß-diaminopropionic acid (ß-ODAP) content in Lathyrus sativus: the integration of nitrogen and sulfur metabolism through ß-cyanoalanine synthase

Author
item XU, QUANLE - Northwest Agricultural & Forestry University
item LIU, FENGJUAN - Northwest Agricultural & Forestry University
item CHEN, PENG - Northwest Agricultural & Forestry University
item JEZ, JOSEPH - Washington University
item Krishnan, Hari

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2017
Publication Date: 2/28/2017
Publication URL: http://handle.nal.usda.gov/10113/5661733
Citation: Xu, Q., Liu, F., Chen, P., Jez, J.M., Krishnan, H.B. 2017. ß-N-oxalyl-L-a,ß-diaminopropionic acid (ß-ODAP) content in Lathyrus sativus: the integration of nitrogen and sulfur metabolism through ß-cyanoalanine synthase. International Journal of Molecular Sciences. 18(3). doi: 10.3390/ijms18030526.

Interpretive Summary: Legumes are inexpensive source of highly nutritious and well-balanced human dietary protein. Among them, grasspea is widely cultivated as an edible and forage crop in arid and semi-arid regions. Consumption of grasspea as a main or sole diet for several months causes lathyrism, a neurodegenerative syndrome that results in the paralysis of lower limbs. The use of grasspea is limited by the presence of a neurotoxin (ß-ODAP) in the seeds. In this manuscript we have reviewed the various factors that regulate the accumulation of neurotoxin and provide strategies to lower/eliminate its accumulation. Information provided in this manuscript should enable researchers to target key genes to lower the accumulation of the neurotoxin in grasspea seeds. Neurotoxin-free grasspea should drastically reduce the incidence of lathyrism encountered in people living in drought-prone areas of Asia and Africa and may open new markets in the U.S.

Technical Abstract: Grasspea (Lathyrus sativus L.) is an important legume crop grown mainly in South Asia and Sub-Saharan Africa. This under utilized 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 ß-N-oxalyl-L-a,ß-diaminopropionic acid (ß-ODAP). Long-term consumption of Lathyrus and ß-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 ß-ODAP. The biosynthetic pathway leading to the production of ß-ODAP is poorly understood, but is linked to sulfur metabolism. To date, only limited studies have been conducted in grasspea on the sulfur assimilatory enzymes and how these enzymes regulate the biosynthesis of ß-ODAP. Here, we review the current knowledge on the role of sulfur metabolism in grasspea and its contribution to ß-ODAP biosynthesis. Additionally, we present our recent work on cloning and manipulation of ß-cyanoalanine synthase, a key enzyme in ß-ODAP biosynthetic pathway. Unraveling the fundamental steps and regulation of ß-ODAP synthesis in grasspea will be vital for the development of improved varieties of this under utilized legume.