Isomers of zeatin and zeatin riboside in clubroot tissue: evidence for trans‐zeatin biosynthesis by Plasmodiophora brassicae

Cytokinin‐like substances in both healthy and infected ( Plasmodiophora brassicae ) Wor. strain S) roots of Brassica campestris L. ssp. pekinensis cv. Granat have been tentatively identified and quantified by HPLC. The isomers of the cytokinins could be seperated on a reversed phase column using a gradient elution with increasing amounts of methanol. Secondary plasmodia were isolated mechanically from Plasmodiophora brassicae infected roots. The time course of adenine uptake and its conversion to cytokinins were investigated. Evidence is presented for the incorporation of [U‐ 14 C]‐adenine into trans ‐zeatin by secondary plasmodia.