METABOLISM OF AMITROLE IN APPLE .3. MODEL SYSTEMS

Excised shoots from apple trees and cell suspension cultures were used as model systems to study the metabolism of [3,5-C-14] amitrole in Ma lus domestica Borkh. Significant differences in the metabolism of the compound applied were observed with excised shoots, cultured cells and whole apple trees. The major metabolite in excised shoots was aminotr iazolylalanine which occurred both in the free form and as conjugates. The major metabolite from whole plants, triazolylalanine, was detecte d in shoots in minor amounts only. In cell suspension cultures, the ty pe of metabolism strongly depended on the concentration of amitrole wh en initially applied. At 10(-3) m or lower, mainly aminotriazolylalani ne was formed. Depending on the concentration of the active ingredient , this metabolite predominantly occurred in free form or as glycosides . At concentrations above 5 x 10(-4) m a new metabolite, 3,5-dihydroxy triazole, was detected which was the only metabolite found at 5 x 10(- 3) m. Significant amounts of non-metabolized amitrole remained in the medium.