During plant development, distantly-located organs must communicate in order to adapt morphological and physiological features in response to environmental inputs. Among the recognized signaling molecules, a class of phytohormones known as the cytokinins functions as both local and long-distance regulatory signals for the coordination of plant development. This cytokinin-dependent communication...

Cytokinins are plant hormones that may play essential and crucial roles in various aspects of plant growth and development. Although the functional significance of exogenous cytokinins as to the proliferation and differentiation of cells has been well documented, the biological roles of endogenous cytokinins have remained largely unknown. The recent discovery of the Arabidopsis Histidine Kinase...

Cytokinins have been implicated in many developmental processes and environmental responses of plants, including leaf senescence, apical dominance, chloroplast development, anthocyanin production, and the regulation of cell division and sink/source relationships. They were identified in the pioneering work of Skoog and Miller (1957) by their ability to promote cell division in cultured cells in...

Partly dehydrated tobacco leaf tissue (Nicotiana rustica), stripped of the lower epidermis, was used to study the effect of kinetin on the rate of rehydration. Depending on the rate of rehydration in untreated tissue, kinetin either increased or decreased rehydration rates. The response to kinetin was very rapid and could be discerned in less than 2 minutes. On extensive dehydration, the tissue...

In order to test the metabolic stability of 9-substituted cytokinins, 6-benzylamino-9-methyl purine has been synthesized and labeled with (14)C in the 9-methyl carbon or doubly labeled with (14)C in the 9-methyl carbon and (3)H in the methylene moiety of the side chain. Although the 6-benzylamino-9-methylpurine is chemically stable, cytokinin-requiring tissues begin removing the 9-substituent i...

Cytokinins are a class of phytohormones involved in various physiological events of plants. The Arabidopsis sensor histidine kinase CRE1 was recently reported to be a cytokinin receptor. We used a steroid-inducible system to show that the transcription factor-type response regulator ARR1 directs transcriptional activation of the ARR6 gene, which responds to cytokinins without de novo protein sy...

The plant hormones cytokinins play a central role in regulating cell division and developmental events. Cytokinin oxidase regulates the levels of these plant hormones by catalyzing their irreversible oxidation, which contributes to the regulation of various morpho-physiological processes controlled by cytokinins. In this study, the crystallization and preliminary X-ray diffraction analysis of t...