| Abstrakt: |
Abstract: Incoproration of 14C-mevalonic acid into fractions of free cytokinins of intact seedlings of spring barley after removal of endosperm was studied. Significant incorporation of 14C into the cytokinin fractions confirmed the mevalonic acid as cytokinin precursor. It represents 30 % and 20 % of the label in roots and leaves, respectively, in intact plants. Isolated leaves are incapable of 14C-mevalonic acid incorporation into the free cytokinin fractions. Increased incorporation (60 %) was found in barley cultivars resistant to powdery mildew (cv. Elgína and Korál) as compared to the susceptible (cv. Slovenský dunajský trh, 50 %). A single cytokinin active fraction corresponding to zeatin was identified by a two-dimensional TLC in young barley roots and leaves. A simple procedure for purification of cytokinins from barley seedlings using cation exchangers Dowex 50, Amberlit IR and Wofatit is described. |
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