ODAP (N-oxalyl-L-2,3-diaminopropionic acid) is present in the seeds of grass pea. In this study, variation of total ODAP accumulation in leaves throughout the crop growth starting from 40 days after sowing to maturity, and the distribution pattern of ODAP in different plant parts including the seeds at the mature stage was analyzed. Five grass pea accessions were evaluated for two subsequent growing seasons in one location of ICARDA, Aleppo (Syria). The results found that the rate of accumulation of total ODAP varied during plant development. Increased rates of synthesis were noticed in young leaves of grass pea. The highest total ODAP content in leaves was noted in the early growth stage (40-50 days after sowing). Mean total ODAP content in leaves ranged from 0.17 to 0.96 percent during 2010-2011 and from 0.19 to 1.28 percent during 2011-2012. During maturity, the total ODAP content was lowest in the seeds than in leaves, stems, pod cover, seed coat, and cotyledons. The ranges of total ODAP content were 0.13 (seed)-0.34 (stem), 0.20 (seed)-1.01 (leaf), 0.22 (seed)-0.62 (leaf), 0.21 (seed)-0.66 (leaf), and 0.21 (seed)-0.78 (leaf) percent in B387, B222, B390, Bio-520, and B587 accessions, respectively, during maturity. The results indicated that the rate of accumulation and synthesis of total ODAP varied during the plant lifespan. The lowest total ODAP content of leaves was observed after 130 days of sowing. The lower total ODAP content after the early vegetative stage of grass pea plants makes them suitable as a feed.
Keywords: Lathyrus sativus; ODAP; grass pea; growth stage; neurolathyrism; neurotoxin; non-protein amino acids.