Zeatin

About: Zeatin is a research topic. Over the lifetime, 2467 publications have been published within this topic receiving 64092 citations. The topic is also known as: Zeatin & (E/Z)-zeatin.

Cytokinin signalling systems

Abstract: A role of endogenous cytokinins as the hormonal signal, by which the roots regulate leaf metabolism and prevent leaf senescence in particular, is discussed. Cytokinin signal perception and transduction in leaf cells were studied on fully expanded first leaves of 10–13-day-old barley plants (Hordeum vulgare L. cv. Viner). Their high sensitivity to exogenous cytokinins depends on dramatic decrease in endogenous cytokinin content during leaf growth. Cytokinin-binding protein of 28–30 kD was isolated from barley leaf cytosol by its affinity to synthetic cytokinin benzyladenine (BA) The 30-kD protein was involved in cytokinin-dependent activation of RNA synthesis in vitro in the system containing chromatin-bound RNA polymerase I from barley leaves. Multistage purification of the protein included affinity chromatography on trans-zeatin-Sepharose or zeatin riboside-Sepharose resulted in isolation of barley leaf cytosol 67-kD protein up to electrophoretic homogeneity. The protein was revealed as a single band in Western blot analysis developed with anti-idiotype antibodies from antiserum to zeatin. In concert with trans-zeatin the 67-kD protein activated transcription elongation directed by RNA polymerase I (in the system containing chromatin-bound RNA polymerase I from barley leaves) and by RNA polymerase II (in nuclei isolated from barley leaves). The protein effect strongly depended on cytokinin concentration. The maximum activation was observed at trans-zeatin concentration of 10-8 M. cis-Zeatin had no effect. These results together with data on reversible [3H]zeatin-binding moiety of the 67-kD protein [8] provide a definitive proof to consider this protein as one of the cytokinin receptors in barley leaf cells which is responsible for cytokinin activation of transcription elongation directed by both RNA polymerase I and RNA polymerase II.

Developmental Patterns of Phytohormone Content in the Cortex and Pith of Potato Tubers as Related to Their Growth and Starch Content

Abstract: The contents of ABA, IAA, and cytokinins (zeatin + zeatin riboside) were determined in the cortex and pith of medium-sized (25 g) and large (120 g) tubers of potato (Solanum tuberosum L., cv. Malakhit) at the end of the flowering phase (48 days after sprouting) and related to plant growth (cell division and enlargement) and starch biosynthesis and deposition. The patterns of phytohormone distribution were different in the cortex and pith. In the latter, with most cells at the enlargement phase, the IAA content increased, as well as the ratios IAA/ABA and IAA/cytokinins. In the cortex dominated by the dividing cells, the ABA content declined, and the ratio cytokinins/ABA exceeded that in the pith. The enhancement of starch synthesis and accumulation in the pith and the retardation of these processes in the cortex followed the changes in the ABA content providing indirect support to the previously made observation that the exogenous ABA promoted starch biosynthesis. The data obtained are discussed in the context of the hormonal control of carbohydrate metabolism and starch deposition in growing tubers.

Effect of cytokinins and sucrose concentration on the efficiency of micropropagation of ‘Zes006’ Actinidia chinensis var. chinensis, a red-fleshed kiwifruit cultivar

Abstract: The effect of N6(3-hydroxybenzyl)adenine (meta-Topolin—mT) was compared with that of N6-benzylaminopurine (BAP) and zeatin at the proliferation stage of micropropagation of red-fleshed Actinidia chinensis var. chinensis ‘Zes006’ in two separate experiments. Shoot number, shoot weight, leaf number and leaf area were significantly higher in mT-supplemented media compared with BAP or zeatin. When transferred to rooting media, plantlets that were propagated in mT-supplemented media readily produced roots, enabling easy acclimation to the greenhouse, whereas none of the plantlets propagated in BAP- or zeatin-supplemented media produced roots. Using 12 pairs of Simple Sequence Repeat primers designed for A. chinensis var. chinensis, a very low rate of somaclonal variation was detected at some loci in plantlets produced in zeatin- (1.04%), BAP- (0.4%) as well as in mT- (0.2%) supplemented media. Overall, mT in equimolar concentrations was the better cytokinin for tissue culture of ‘Zes006’ kiwifruit and may well be applicable to many other kiwifruit genotypes. Supplementation of media with meta-Topolin for in vitro propagation of the red-fleshed kiwifruit cultivar ‘Zes006’ enhanced better shoot proliferation, giving healthy plantlets that were easier to acclimatize to the greenhouse environment compared with media supplemented with 6-benzylaminopurine or zeatin. It also induced a lower rate of somaclonal variation, as detected by SSR markers.

Cytokinins from soils.

Abstract: Substances that coeluted with zeatin and zeatin riboside were extracted from soils supporting plants growing in symbiotic association with microorganisms.