Uptake, distribution and metabolic fate of 3H-triforine in plants .I. Short-term experiments

Most of the label, present in the roots of bean, tomato and barley seedlings after short‐term root‐treatment with 3H‐triforine, appeared only weakly adsorbed on to the root tissue and was desorbed after transplanting in fungicide‐free soil. Label taken up accumulated almost exclusively in the leaves present at the time of treatment; all leaves expanding after termination of the treatment remained virtually devoid of radioactivity. In “adult” plants label was usually present in a concentration gradient from roots to youngest leaves; in tomato plants, however, distribution of label was rather irregular. Time‐course studies with bean and barley plants revealed that the aerial parts were gradually supplied with label, from old to youngest leaves, the maximum relative accumulation of radioactivity slowly moving acropetally. Under the experimental conditions chosen, triforine was converted nearly quantitatively to one metabolite, which almost certainly is different from any known non‐enzymic breakdown product of the fungicide.