The in vitro metabolism of [8-14C]benzyladenine by excised organs of tomato plants

The metabolic fate of 8-¹⁴C]benzyladenine applied to the excised organs of tomato (Lycopersicon esculentum Mill. cv. Heinz 1370) was investigated after 2 and 6 h of feeding. Although the roots were the most effective at uptake of the cytokinin the leaves metabolised it the most efficiently. The predominant metabolite in all of the tissues was an unknown compound which did not have a retention time corresponding with any of the standards used. The roots contained the most extensive range of metabolites which included the unknown metabolite and compounds co-eluting with adenine, and the riboside, nucleotide and 9-glucoside of benzyladenine. The 9-glucoside was detected only in the root material. The stem yielded the highest levels of radioactivity at the retention times of benzyladenosine-5-monophosphate and benzyladenosine. The radioactivity associated with these two cytokinins was transient in the leaf extract. This organ ultimately yielded radioactivity only at the retention times of the unknown metabolite and adenine. Since only the roots and leaves contained relatively large peaks of radioactivity at the elution volume of adenine it seems that degradative metabolism was more predominant in these organs than in the stem.Abbreviations Ade adenine - Ado adenosine - BA benzyladenine - BAR benzyladenosine - BA3G 3-glucosylbenzyladenine - BA9G 9-glucosylbenzyladenine - BARMP benzyladenosine monophosphate - HPLC high performance liquid chromatography - MS mass spectrometry