Cytokinins (CKs) play a crucial role in various phases of plant growth and development, but the basic molecular mechanisms of their biosynthesis and signal transduction only recently became clear. The progress was achieved by identifying a series of key genes encoding enzymes and proteins controlling critical steps in biosynthesis, translocation, and signaling. Basic schemes for CK homeostasis ...

The cytokinins constitute one of the five groups of plant hormones, and are characterised by their ability to promote cell division in cultured plant callus tissue under appropriate conditions [I-31. With the exception of diphenylurea, all cytokinins that have been unambiguously identified in extracts of higher plants are derivatives of adenine, including 6-aminoand riboside-substituted compoun...

Lychee (Litchi chinensis) has been analyzed for cytokinins in buds before and after flower bud differentiation, using reversephase high performance liquid chromatography in combination with Amaranthus bioassay and gas chromatography-mass spectrometry-selected ion monitoring. Four cytokinins, zeatin, zeatin riboside, N(6)-(delta(2)-isopentenyl)adenine, and N(6)-(delta(6)-isopentenyl) adenine rib...

The accumulation o f betacyanin was reduced by the addition o f various cytokinins to sus­ pension cultures o f Phytolacca americana. The decrease in the accumulation o f betacyanin was overcome by exogenously supplied tyrosine which is a precursor o f betacyanin. Benzylaminopurine (BAP) decreased the level o f free tyrosine in the cells. Feeding experiments using labeled tyrosine revealed that...