Trans-zeatin in culture filtrates of Agrobacterium tumefaciens

Cytokinin-active bases and nucleosides have been isolated from the culture filtrates of Agrobacterium tumefaciens by trace enrichment onto octadecyl-silica and have been identified by GLC-MS of their permethyl and trimethylsilyl derivatives. Besides the expected 6-(3-methylbut-2-enylamino) purine, the filtrate contained zeatin (85% trans, 15% cis), 2-methylthio-ribosylzeatin and smaller quantities of ribosylzeatin and other cytokinin-active nucleosides.