Uptake and Translocation of [14C] -Monoethanolamine in Barley Plants

Summary Uptake and translocation of [ 14 C]-monoethanolamine and its hydrochloride were investigated after application to an unwounded part of the fifth leaf from the main shoot of intact spring barley plants. After 48 and 72 h, respectively, the free EA-base was both absorbed rapidly and translocated out of the feeding leaf. The absorbed [ 14 C] preferably migrated to the tillers, which resulted in an approximately uniform distribution of the radioactivity in the aboveground parts of the plant after the uptake phase (similar [ 14 C]- concentrations in the main shoot and tillers), whereas only few radioactivity moved to the roots. On the other hand, the protonated EA (EA-HCI) exhibited both a reduced uptake and a restricted mobility. The bulk of radioactivity remained in the main shoot. As a consequence of the principally analogous metabolism of EA and its protonated form, the translocation differences are compensated during ontogenesis. When the plants reached maturity, similar distribution patterns could be found in which the kernels represented a considerable sink.