The uptake and the transport of14C-labeled epibrassinolide in intact seedlings of cucumber and wheat

Abstract

The uptake and the transport of exogenously applied epibrassinolide (EBR) in seedlings of cucumber and wheat were examined by autoradiography using14C-EBR.14C-EBR was applied to roots, young and mature leaves, and the shoot apex. When applied to roots,14C-EBR was readily taken up and was swiftly transported throughout both plant species. When14C-EBR was applied to the adaxial surface of a young cucumber leaf, it was readily taken up, but was very slowly transported. In cucumber leaves,14C-EBR was transported throughout the treated leaf after 3 days of treatment, and then it was transported to upper leaves from the treated leaf after 7 days. Some 6.3% of applied14C-EBR was transported to the newly expanded leaves. In wheat leaves,14C-EBR was transported only in the apical direction from the treated spot after 3 days of treatment, but it was not transported from the treated leaf to the other leaves or organs even after 7 days. Some 1.3% of applied14C-EBR was transported to the tip area of the treated leaf. These results indicate that exogenous EBR applied to intact plants is acropetally transported.