The biosynthesis of the Lathyrus neurotoxin 3-N-oxalyl-L-2,3-diaminopr
opanoic acid (beta-ODAP) was examined in the ripening seeds and fruit
of Lathyrus sativus. It was found that the incorporation of [C-14]-lab
el from the precursor beta-(isoxazolin-5-on-2-yl)-alanine into beta-OD
AP occurs in intact fruits as well as in separated pericarp and immatu
re seeds, in both a high and low toxin variety. This incorporation gra
dually decreases in the pericarp while increasing in the maturing seed
. Only in the final stage of maturity is the biosynthesis lower in the
low toxin variety. In germinating seeds of Crotalaria incana this inc
orporation does not take place.