Analysis of cytokinin nucleotides by capillary zone electrophoresis with diode array and mass spectrometric detection in a recombinant enzyme in vitro reaction.

A capillary zone electrophoresis (CZE) method for separation of adenosine and N(6)-isopentenyladenosine (cytokinin) nucleotides was developed, optimized and validated. Aqueous solutions of several amino acids were evaluated as the background electrolyte constituents. Separation of six nucleotides in less than 20 min with high theoretical plate number (up to 400000 for isopentenyladenosine triphosphate) was achieved using a 100 mM sarcosine/ammonia buffer at pH 10.

Rhodococcus fascians impacts plant development through the dynamic fas-mediated production of a cytokinin mix.

The phytopathogenic actinomycete Rhodococcus fascians D188 relies mainly on the linear plasmid-encoded fas operon for its virulence. The bacteria secrete six cytokinin bases that synergistically redirect the developmental program of the plant to stimulate proliferation of young shoot tissue, thus establishing a leafy gall as a niche. A yeast-based cytokinin bioassay combined with cytokinin profiling of bacterial mutants revealed that the fas operon is essential for the enhanced production of isopentenyladenine, trans-zeatin, cis-zeatin, and the 2-methylthio derivatives of the zeatins.

Novel potent inhibitors of A. thaliana cytokinin oxidase/dehydrogenase.

The synthesis of a new group of 2-X-6-anilinopurines, including compounds with potential cytokinin-like activities, with various substitutions (X=H, halogen, amino, methylthio or nitro) on the phenyl ring is described. The prepared compounds have been characterized using standard physico-chemical methods, and the influence of individual substituents on biological activity has been compared in three different bioassays, based on the stimulation of tobacco callus growth, retention of chlorophyll in excised wheat leaves and the dark induction of betacyanin synthesis in Amaranthus cotyledons. The biological activity of the prepared compounds was also assessed in receptor assays, in which the ability of the compounds to activate the cytokinin receptors AHK3 and AHK4/CRE1 was studied.