Accumulation of vicine and convicine in Vicia faba and V-narbonensis

The pyrimidone glucopyranosides vicine and convicine were found in the roots of V. faba and V. narbonensis. The total amount present in the roots per plant at flowering exceeded that in one mature seed of V. narbonensis, indicating net synthesis. In V. faba the amount of pyrimidone glucopyranosides delivered per seed could account for the amount in the roots, but only if inter-conversion of the two compounds occurred. Stems contained very low levels of these compounds, and only in the first harvest of V. faba, whereas leaf laminae, pod walls and funicles lacked detectable amounts. A transitory peak was found in testae, which declined as accumulation took place in the cotyledons. In both testae and cotyledons the accumulation of pyrimidone glucopyranosides took place early in the growth of such tissues. The amounts accumulating in seeds, and particularly in testae and cotyledons, were much greater in V. faba than in V. narbonensis. Grafting between a low pyrimidone glucopyranoside mutant and its parent line demonstrated that the roots do not influence the concentration in the seeds. The probable site of synthesis for the developing fruits is the testa, with some additional synthesis in vegetative tissues leading to accumulation in the roots, at least in V. narbonensis.