Hormones in Plants Bearing Nitrogen-fixing Root Nodules: Cytokinin Transport from the Root Nodules ofAlnus glutinosa(L.) Gaertn.

Abstract

The movement and metabolism of [8-14C]zeatin applied to the root nodules of Alnus glutinosa (L.) Gaertn. was investigated. Twenty-four hours after the start of uptake, zeatin and a number of its metabolites were detected in all parts of the plant. The major radioactive compounds present in a cationic fraction of different plant parts at this time co-chromatographed on Sephadex LH20 with zeatin (in nodules, stems, and leaves) and with zeatin riboside (in roots, stems, and buds). In the roots, in addition to the peak co-chromatographing with zeatin ribo side, there was also a prominent unidentified polar peak. The presence of zeatin and zeatin riboside in the stems and leaves was indicated also by chromatographic behaviour in other systems, effects of permanganate oxidation, and co crystallisation with the authentic unlabelled compounds. Biological activity was exhibited by both peaks in the soybean callus bioassay. Other metabolites in the shoot, possibly active as cytokinins, had the characteristics of dihydrozeatin, zeatin or dihydrozeatin-5'-nucleotide(s), and zeatin or dihydrozeatin glucosides. The gradual disappearance with time of zeatin and its riboside from the shoot was accompanied by an increase in the proportion of more polar meta bolites.