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.

Natural plant hormones cytokinins increase stress resistance and longevity of Caenorhabditis elegans.

Abstract: Cytokinins are phytohormones that are involved in many processes in plants, including growth, differentiation and leaf senescence. However, they also have various activities in animals. For example, kinetin and trans-zeatin can reduce levels of several aging markers in human fibroblasts. Kinetin can also protect mice against oxidative and glyoxidative stress, and prolong fruit flies’ lifespan. Additionally, several cytokinins are currently used in cosmetics. To extend knowledge of the breadth of cytokinins’ activities, we examined effects of natural cytokinin bases on the model nematode Caenorhabditis elegans. We found that kinetin, para-topolin and meta-topolin prolonged the lifespan of C. elegans. Kinetin also protected the organism against oxidative and heat stress. Furthermore, our results suggest that presence of reactive oxygen species, but not DAF-16 (the main effector of the insulin/insulin-like growth factor signaling pathway), is required for the beneficial effects of kinetin. Ultra-high performance liquid chromatography-tandem mass spectrometric analysis showed that kinetin is unlikely to occur naturally in C. elegans, but the worm efficiently absorbs and metabolizes it into kinetin riboside and kinetin riboside-5′-monophosphate.

The Uptake of Cytokinins by Protoplasts and Root Sections of Brassica campestris

Abstract: The effect of cytokinins was studied on the incorporation of 14C-labelled precursors into the nucleic acid fraction of protoplasts isolated from callus or roots of Brassica campestris. Protoplasts from callus and roots took up 14C-uridine from the incubation medium and incorporated this precursor into the ribonucleic acid fraction during the experimental period of 16 h. Low concentrations of kinetin (10−8-5 × 10−6M) did not stimulate the incorporation, and kinetin inhibited this process at higher concentrations (5 × 10−5M). This result led to an investigation on the uptake of cytokinins by protoplasts of roots. In contrast to a rapid uptake of radio-actively labelled adenine and uridine. protoplasts from roots took up only small amounts of labelled kinetin. zeatin, zeatin riboside and zeatin nucleotides from the incubation medium. Root sections took up far more adenine and kinetin than protoplasts from roots. The ratio between the amount of kinetin taken up and applied was much higher for the sections than for protoplasts, indicating that intact root cells took up kinetin far more rapidly than protoplasts. It is suggested that the plasmalemma and cell wall play an essential role in the uptake of cytokinins or that the differences in the uptake rates are related to differences between the rates of metabolism of cytokinins in root sections and in protoplasts.

An efficient multiple shoot induction and genetic fidelity assessment of Exacum bicolor Roxb., an endemic and endangered medicinal plant

Abstract: Exacum bicolor, an endemic and endangered medicinal plant, belongs to the family Gentianaceae. A rapid protocol has been developed for efficient multiple shoot induction by testing nodal explants on Murashige and Skoog (MS) medium supplemented with various cytokinins. The cytokinins 6-benzyladenine (BA), 6-furfurylaminopurine (Kn), 2-isopentenyladenine (2-iP) and zeatin (Zn) were used individually and in combination at different concentrations (0.5, 1.0, 2.0, 5.0, and 10.0 μM). The maximum number of shoots (19.33 ± 1.09 per explant) as well as their fresh weight (5.1 ± 0.68 g) and dry weight (216.83 ± 2.84 mg) were obtained with 10.0 μM BA + 2.0 μM Kn. After 4 wk, the multiple shoots from agar culture were subcultured into liquid medium containing the same growth regulator combinations. After 8 wk of liquid culture, the best treatment had about tenfold increase in shoot number (199.5 ± 1.14 per explant). The fresh weight (13.76 ± 0.14 g) and dry weight (909.33 ± 1.92 mg) were highest with full strength MS medium supplemented with 3% sucrose and containing 10.0 μM BA + 2.0 μM Kn. Maximum root development was observed after 30 d with 0.5 μM indole-3-butyric acid (IBA) supplementation. Regenerated plants were successfully transferred to pots containing coco peat:perlite mixture and showed a 75% survival rate. Genetic fidelity of in vitro plantlets compared to mother plant were assessed using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeats (ISSR) markers. All the regenerated plants were genetically identical to their mother plant, showing no detectable genetic variation in the regenerated plantlets. Thus, this protocol could be successfully used for mass multiplication and germplasm conservation of E. bicolor.

The Effect of Ringing on Cytokinin Distribution in Salix baylonica

Abstract: Although quantitative differences were observed in the cytokinin content of mature leaves and bark of Salix babylonica it would appear as if these tissues contained the same cytokinin complement. Ringing resulted in a decrease in the level of cytokinins in the leaves and an increase in the bark, both above and below the girdle. In the leaves the decrease was due mainly to a drop in the level of those compounds that co-chromatographed with the cytokinin glucosides. These compounds were also almost undetectable in the bark above the girdle, where callus was formed. The observed increase in the cytokinin content of the bark above the girdle was due to higher activity in those parts of the chromatograms where zeatin and zeatin riboside occurred. Ringing stimulated the growth of lateral buds below the girdle. These developing buds as well as the bark below the girdle contained very high levels of cytokinins that cochromatographed with zeatin and zeatin riboside.