Genotypic variation in cytokinin oxidase has been detected in enzyme preparations from Phaseolus vulgaris L. cv Great Northern and Phaseolus lunatus L. cv Kingston callus cultures. Although cytokinin oxidase preparations from Great Northern and Kingston callus tissues appear to have very similar substrate specificities, the cytokinin oxidase activities from the two callus tissues were found to ...

Many aspects of plant development are regulated by antagonistic interactions between the plant hormones auxin and cytokinin, but the molecular mechanisms of this interaction are not understood. To test whether cytokinin controls plant development through inhibiting an early step in the auxin response pathway, we compared the effects of cytokinin with those of the dgt (diageotropica) mutation, w...

Plants have evolved elaborate mechanisms for sensing and responding to sub-optimal environmental conditions. Abiotic stresses caused by these conditions trigger a wide range of local and long-distance signals which must be co-ordinated and integrated into whole-plant processes, such as development, in order for the plant to respond properly and survive. Several hormones function as key regulato...

BACKGROUND Plant responses to phytohormone stimuli are the most important biological features for plants to survive in a complex environment. Cytokinin regulates growth and nutrient homeostasis, such as the phosphate (Pi) starvation response and Pi uptake in plants. However, the mechanisms underlying how cytokinin participates in Pi uptake and Pi signaling are largely unknown. In this study, we...

Morphogenetic signals control the patterning of multicellular organisms. Cytokinins are mobile signals that are perceived by subsets of plant cells. We found that the responses to cytokinin signaling during Arabidopsis development are constrained by the transporter PURINE PERMEASE 14 (PUP14). In our experiments, the expression of PUP14 was inversely correlated to the cytokinin signaling readout...

Auxin acts synergistically with cytokinin to control the shoot stem-cell niche, while both hormones act antagonistically to maintain the root meristem. In aluminum (Al) stress-induced root growth inhibition, auxin plays an important role. However, the role of cytokinin in this process is not well understood. In this study, we show that cytokinin enhances root growth inhibition under stress by m...

Heat shock (HS) at 40 degrees C was given to the root system of Nicotiana tabacum wild type (WT) and to HSIPT transgenic plants transformed with the bacterial cytokinin biosynthesis gene isopentenyltransferase (ipt) cloned behind the heat shock 70 promoter from Drosophila melanogaster. HS increased cytokinin concentrations in roots and leaves of transgenic plants. The effect was smaller in WT p...

The phytohormone cytokinin regulates various aspects of plant growth and development, including root vascular development. In Arabidopsis thaliana, mutations in the cytokinin signaling components cause misspecification of protoxylem cell files. Auxin antagonizes cytokinin-regulated root protoxylem differentiation by inducing expression of Arabidopsis phosphotransfer protein6 (AHP6), a negative ...

Mutations at the cytokinin biosynthesis locus (tmr) of Agrobacterium tumefaciens usually result in strains that induce tumors exhibiting the rooty phenotype associated with high auxin-to-cytokinin ratios. However, tobacco (Nicotiana tabacum cv Havana 425) leaf disc explants responded to tmr- mutant strain A356 by producing rapidly growing, unorganized tumors, indicating that these lines can gro...

Cytokinins are hormones that play an essential role in plant growth and development. The irreversible degradation of cytokinins, catalyzed by cytokinin oxidase, is an important mechanism by which plants modulate their cytokinin levels. Cytokinin oxidase has been well characterized biochemically, but its regulation at the molecular level is not well understood. We isolated a cytokinin oxidase op...