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.

Influence of White Clover Mosaic Potexvirus Infection on the Endogenous Cytokinin Content of Bean

Abstract: The cytokinin content in the primary leaves of bean ( Phaseolus vulgaris ) was monitored for 10 d after inoculation with white clover mosaic potexvirus. The cytokinins were isolated, purified, separated by high-performance liquid chromatography, and quantified by radioimmunoassay. The cytokinins detected at the time of inoculation (d 0) were: (a) the free bases, zeatin (Z), dihydrozeatin (DZ), and isopentenyladenine; (b) the riboside, DZ riboside (DZR); (c) the O- glucosides of DZ, DZR, and Z riboside; (d) the nucleotides, Z riboside-5′-monophosphate and isopentenyladenosine-5′-monophosphate; and (e) trace amounts of Z-9-glucoside and DZ-9-glucoside. During the 10 d after inoculation with white clover mosaic potexvirus, marked quantitative changes in this cytokinin profile were observed. The concentration of the free bases and DZR decreased, accompanied by an increase in the 9-glucosides and the nucleotides. Virus titer increased rapidly 3 d after inoculation, attaining a maximum level at d 5. This increase coincided with the increases in the 9-glucosides and the nucleotides. We propose that the decline in the cytokinin free bases and riboside may allow the increase of virus titer in bean and lead to the senescence of infected leaves.

Effects of auxins and cytokinins on growth and rosmarinic acid formation in cell suspension cultures of Anchusa officinalis

Abstract: Cell suspension cultures of Anchusa officinalis required exogenous phytohormones for their normal growth. Cell lysis was observed at the third passage in a hormone-free medium. Using hormone — depleted cells, the effects of auxins (2,4-D, NAA, IAA and CFP) and cytokinins (BA, kinetin, and zeatin) on cell growth and RA production were investigated. All auxins tested could maintain growth and integrity of the cells whereas cytokinins alone could not, suggesting that this culture is auxindependent. Among the auxins tested, NAA had a pronounced effect on RA production. The total RA content obtained at optimum NAA concentration (0.25 mg/l) reached 1.7 g/l (12% of dry weight). The kinetics of growth and RA production suggested that the increase in final RA content was due to both an increase in the rate of RA synthesis and initiation of the period of synthesis in the exponential rather than the linear growth phase.

Cytokinin metabolites and gradients in wild type and transgenic tobacco with moderate cytokinin over‐production

Abstract: A binary T-DNA plant expression vector carrying a promoterless isopentenyl transferase (ipt) gene was constructed and used to transform Nicotiana tabacum L. Several primary transformants were obtained that displayed a range of phenotypes characteristic of cytokinin over-production. Two of the transformants with moderately altered phenotypes, both of which produced viable offspring and expressed the ipt gene at a low level, were selected for use in studies of the regulation of cytokinin metabolism. Both lines were found to contain high concentrations of zeatin-7-glucoside (Z7G), indicating that Z7G can accumulate in plants even when the rate of endogenous overproduction of cytokinins is low. This supports the hypothesis that 7-glucosidation is an important step in the regulation of zeatin (Z) levels. Very sharp gradients in concentration of cytokinin riboside and ribotides, related to age of tissue and distance from the apex, were found in both wild type and transfomed plants, which could be important in developmental regulation and could also account for some of the discrepancies between reported cytokinin levels in various plants. Intriguingly, however, although the combined level of zeatin riboside and ribotide was much higher in the transformed plants than in wild type, the combined level of isopentenyl riboside and ribotide was lower.

Concentration Gradients of trans-Zeatin Riboside and trans-Zeatin in the Maize Stem: Measurement by a Specific Enzyme Immunoassay.

Abstract: A sensitive, specific enzyme immunoassay (EIA) for trans-zeatin riboside (ZR) and trans-zeatin (Z) in the 0.3 to 30 picomole range has been described. The reliability of the method for measuring ZR + Z in partially purified extracts of Zea mays L. tissues was verified by highperformance liquid chromatography. EIA measurements showed that there was a concentration gradient of ZR + Z along the length of the Zea stem. The topmost internodes, internodes 7 and 8 counting from the coleoptilar node, had the highest concentration ( approximately 130 picomoles per gram fresh weight). Moving basipetally, the concentration dropped approximately 10-fold to a minimum at internode 4, and then increased slightly in internodes 2 and 3. There were also gradients within each internode. The five lowest internodes contained the highest concentrations toward their apical end, the region which included the node; this asymmetry was less pronounced near the top of the plant.

Plant regeneration from protoplasts of Capsicum annuum.

Abstract: Leaf protoplasts were isolated from axenic shoot cultures of four varieties of Capsicum annuum (Americano, Dulce Italiano Florida Gynat and Nigrum) and a wild species C. chinense. Protoplasts of both species, cultured in KM8P medium and using agarose bead culture, entered division with the exception of the variety Nigrum. Cell colonies formed callus in agar-solified MS medium supplemented with zeatin and for C. annuum v. Dulce Italiano shoots were regenerated when protoplast-derived calli were transferred to MS medium with 6-BAP. Excised shoots were rooted on MS medium which lacked phytohormones.