Isolamento Di Citochinine Dal Rhizobium Leguminosarum Frank

Isolation of Cytokinins from « Rhizobium leguminosarum » Frank. — Three substances with cytokinin activity have been isolated from liquid cultures of Rh. leguminosarum by fractionation on Dowex 50W X4 H+ column, butanol extraction, silver precipitation, chloroform extraction and finally by paper chromatography. The Rf-values and the U.V. absorption maxima of one of these substances were similar to those of isopentenyl adenine, a potent cytokinin synthetized by several bacteria responsible, as Rhizobium, for profound morphological alterations of the tissues of higher plants. The other two substances are not comparable to any of the as yet known natural cytokinins. It is suggested that these substances, produced by Rhizobium, are responsible for tissue proliferation during nodule formation.