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.

Somatic Embryogenesis in Miniature Potted Rose (Rosa hybrida L.)

Abstract: Regeneration via somatic embryogenesis was established for the miniature rose cultivar (Rosa hybrida L. 'Linda'). Initially, in vitro cultures of eight miniature rose cultivars were established and then sufficient amounts of callus were produced on MS-media containing high levels of 2,4-D. Embryogenic callus was induced on calli of six cultivars incubated on media containing either zeatin or thidiazuron (TDZ). Although the frequency of somatic embryogenesis in 'Linda' was only 3.3%, further work on transformation was continued with this cultivar, because of promising results on plant regeneration. ABA was used for proliferation of embryogenic callus, and high concentrations of BAP combined with low concentrations of NAA and GA 3 were used for shoot regeneration and elongation. The observed high demand of auxin for callus induction and of BAP for shoot regeneration appeared to be due to low endogenous concentrations of these hormones in miniature roses. Shoots were rooted on 1/2 MS medium supplemented with IAA and IBA and transferred to the greenhouse. Plants flowered after about 10 weeks and were morphologically indistinguishable from the original plant.

Expressions of A-type and C-type Cyclins Induced by Exogenous Cytokinin Treatment on Leaf Blades and Calli of Rice (Oryza sativa L.)

Abstract: The expression patterns of cyclin genes, which play a crucial role on cell cycle control, were analyzed with rice calli and leaf blades from seedlings. When callus was transferred from media containing the combinations of 2,4-D and kinetin under the dark conditions to medium supplemented with cytokinin-only on 7 days after the cultures, the expression levels of A-, B- and C-type cyclins from callus were increased significantly. Despite the fact that cyclin genes were well expressed on leaf blades rather than other organs in rice seedlings, rice leaf blades grown on the medium containing various combinations and concentrations of cytokinin for 24 hours had no major effect on the expression patterns of cyclins except zeatin. The relation between cytokinin regulation and the expression of cyclins of rice is discussed.

A new approach to the problem of differential quantification of zeatin and zeatin riboside.

Abstract: The development of new refined immunochemical methods is required for examination of the content of endogenous cytokinins in small amounts of plant material. Earlier, we have described some methods of endogenous cytokinin quantification, which were used for determination of the content of zeatin (Z) and zeatin riboside (ZR) in reproductive organs of higher plants [1–5]. These methods are very sensitive and well reproducible, which permits us to apply them for determination of principle forms of endogenous cytokinins in ovaries during early embryogenesis. However, the problem of Z and ZR differential quantification emerges again when we deal with still smaller amounts of the biological material (analysis of ovules, embryo sac, etc.). In this case, the task becomes more difficult, and new approaches are required, which provide for cytokinin quantification without preliminary fractionation of the tested material. Here, we suggest a new micromethod of enzyme immunoassay (EIA) for differential quantification of principle forms of endogenous cytokinins. We examined the hormonal status of Triticum aestivum L. ovules during early embryogenesis to illustrate the possibilities of this approach. The suggested micromethod for cytokinin differential determination can be applied in some fields of biochemistry, endocrinology, and medicine for estimation of low-molecular-weight compounds close in their chemical structure but differing in their biological activities. We used ovaries and ovules at the following developmental phases: mature embryo sac (phase 1), interphase zygote (phase 2), and mitotic zygote (phase 3) [3–5]. Plant material was analysed by solid-phase competitive EIA using labelled anti-rabbit antibodies [6]. The optical density of the product of enzymatic oxidation of 2,2'-azino-bis(3-ethyl-2,3-dihydrobenzthiazoline-6sulfonic acid) (ABTS, Sigma, United States) (2.0 mM) with hydrogen peroxide (2.5 mM) in 0.1 M Na-acetate buffer, pH 4.2, was measured at 405 nm ( A 405 ) using an analyser of enzymic immunoassay reactions (AEIR-01, Uniplan, Russia) [7]. Like routine techniques [8], a new EIA method for quantification of principal forms of endogenous cytokinins is based on the analytical system using antibodies specific for zeatin riboside and the immobilized antigen (ZR). However, as distinct from common EIA method, a new approach uses two standards (Z and ZR) for building the calibration curves. This simplifies the analytical system and facilitates obtaining immunoreagents. In fact, in this case, there is no need in the usage of two parallel immunochemical systems, where two samples of plant material are utilized [1–3] and then the true contents of Z and ZR are calculated from effective concentrations of ZR determined in each of the two systems. The requirement of two samples limits the application of the method when the amount of plant material is very low. A new approach (the method of two standards) implies the analysis of only a single sample in a single EIA system (with sufficient number of recordings), and in addition, there is no need in the preliminary fractionation of the tested material. Thus, we can consider this approach a micromethod for cytokinin determination, which can be used for very small amounts of plant material. A high sensitivity of this method (0.8 × 10 –10 and 0.5 × 10 –10 M of Z and ZR, respectively; Fig. 1, curves 3 , 4 ) permits testing very dilute plant extracts (a dilution 1 : 1000 and more). The TPB buffer (0.01 M K-phosphate buffer, pH 7.4, containing 0.1 M NaCl, 0.1% Triton X-100, and 0.01 M sucrose), which was used for extraction, practically completely neutralized the effects of all components of the cell sap on the results obtained, providing for a high specificity of measurements required for investigations of this type. Thus, the essence of the new method with two standards is determination of two effective concentrations of zeatin ([Z] ef ) and zeatin riboside ([ZR] ef ) from calibration curves built with Z and ZR as standards (Fig. 1, curves 3 , 4 ). It should be noted that (1) free and bound zeatins differently affect the formation of the immunochemical complex between specific antibodies against ZR and the immobilized antigen; (2) ZR displays a highest activity in the inhibition of binding between antibodies and the immobilized antigen; (3) cross-reactivity was equal to 80% for zeatin and 0.1% for dihydrozeatin and isopentyladenine, as A New Approach to the Problem of Differential Quantification of Zeatin and Zeatin Riboside

Mother plant luminescence and zeatin concentration in the in vitro establishment of an olive plant

Abstract: This study aimed to evaluate the effect of the presence and absence of light provided to the mother plant and zeatin concentrations in vitro establishment, to reduce oxidation and promote the establishment of olive explants. The trials were carried out at the Fruit Tree Propagation Lab, Federal University of Pelotas, Brazil. In the first experiment, plants of olive 'Arbequina' were subjected to the absence and presence of light and established on WPM with 0 and 2mg.L-1 zeatin. In the second experiment, plants of olive 'Leccino', 'Arbequina' and 'Frantoio' 'were submitted to the absence of light, and established in vitro on WPM with 0,4 and 8 mg.L-1 Zeatin. Mother plants of olive tree 'Arbequina' in conditions of absence of light are the most suitable in vitro establishment. The concentration of 2 mg.L-1 of zeatin promotes survival of explants of olive 'Arbequina'. The concentrations 0,4 and 8 mg.L-1 of zeatin) results no difference between Leccino and Arbequina cultivars for the variable fungal contamination.