The occurrence of free and bound cytokinins in plasmodia of Plasmodiophora brassicae isolated from tissue cultures of clubroots.

Plasmodia have been isolated from Brassica campestris tissue infected with Plasmodiophora brassicae. Cytokinins were extracted from plasmodia and from the remaining host cytoplasm. Fractions were separated in a butanol soluble fraction containing free cytokinins and a water soluble fraction containing bound forms, presumably glucose-6-phosphate derivatives of zeatin and zeatin riboside. The butanol fraction was analysed by high pressure liquid chromatography (HPLC). The different glucosides were determined after treatment of the water fraction with β-glucosidase.Plasmodia contained zeatin riboside and its glucose derivative (175 and 1600 ng/g dry weight, respectively). Host cytoplasm contained zeatin riboside (132 ng/g dry weight) and small amounts of the glucose-6-phosphate derivatives of zeatin and zeatin riboside. The results suggest that plasmodia synthesize cytokinins which are released into the host cytoplasm inducing host cell division.