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.

In Vitro Propagation and Recovery of Eight Apple and Two Pear Cultivars Held in a Germplasm Bank

Abstract: Eight apple (Malus x domestica) and two pear (Pyrus communis) traditional cultivars of commercial interest were selected from the germplasm bank CIAM (Centro de Investigaciones Agrarias de Mabegondo, NW of Spain) one of the most important collections of The Iberian Peninsula. In order to define the establishment protocol, apical buds 1.0 - 1.5 millimetre length of the selected cultivars were established in solid mineral medium Murashige and Skoog (MS) with modified vitamins (thiamine 10X) and supplemented with 1 mg·L-1 6-benzyladenine (BA), 0.2 mg·L-1 gibberellic acid (GA3) and 0.3 mg·L-1 of indole-3-butyric acid (IBA). The highest shoot initiation rates were achieved with apple cultivar “Principe Grande” (55%) and “Barburina” pear cultivar (50%); the lowest rate was obtained with apple cultivar “Camoesa” (11%). Initiation rates for shoots culture varied between 22% and 37% for the other cultivars. The cytokinins BA, zeatin, 2-isopentyladenine (2iP) and thidiazuron (TDZ) were tested at concentrations of 0, 0.25, 0.5 and 1 mg·L-1 in the absence or presence of IBA (0.1 mg·L-1) for the multiplication step. For all cultivars, the highest multiplication rates were obtained with medium supplemented with TDZ and also in media containing BA. The in vitro rooting success of shoots in medium with 0.1 mg·L-1 IBA without cytokinins, and the survival rate of plantlets acclimatized under greenhouse conditions depended on the genotype of the different cultivars. In vitro propagation of these ten traditional apple and pear cultivars in NW Spain has not previously been reported.

Histological and endogenous plant growth regulators changes associated with adventitious shoot regeneration from in vitro leaf explants of strawberry (Fragaria × ananassa cv. ‘Honeoye’)

Abstract: Few studies have been conducted on the links between histological and hormonal variation during shoot regeneration. Therefore, we investigated this link in strawberry (Fragaria × ananassa cv. ‘Honeoye’). Main plant growth regulators were measured using reverse-phase liquid chromatography–tandem mass spectrometry. Histological observations were conducted to understand the pattern of adventitious shoot regeneration from the leaf segments. After 14 days of dark culture, a mean shoot regeneration frequency of 94.7 % was obtained on MS medium supplemented with 2.0 mg L−1 thidiazuron, 30 g L−1 sucrose, and 6 g L−1 agar (pH 5.9). During shoot regeneration, indole acetic acid (IAA) concentrations increased, abscisic acid (ABA) decreased, and gibberellic acid (GA3) and zeatin showed peaks. The results could be correlated with the cell division and differentiation that occurred during shoot regeneration. Histological observation showed that the adventitious shoots were derived from subepidermal cells and the epidermal cells of the midrib near the cut. The meristemoids, primordia and shoots were formed sequentially on day 6, day 12, and day 18 after culture. During the meristemoids formation on day 6 after culture, IAA rapidly increased from 1.49 to 1.72 ng g−1 fresh weight (Fw), ABA rapidly decreased from 52.61 to 13.47 ng g−1 Fw, and zeatin increased from 1.68 to 5.98 ng g−1 Fw. During primordia formation on day 12 after culture, IAA rapidly increased to 1.88 ng g−1 Fw, ABA rapidly decreased to 2.69 ng g−1 Fw, GA3 peaked at 73.91 ng g−1 Fw, and zeatin peaked at 7.69 ng g−1 Fw. Our results suggested that the histological variations were consistent with the plant hormonal changes during shoot regeneration, and that changes in hormone concentration could be used as a reference to characterize the mode of shoot regeneration.

Cytokinins and the growth of cultured sycamore cells

Abstract: Summary Externally supplied cytokinins can induce cell division in sycamore cultures at cell densities at which, in the absence of a supply of cytokinin, they fail to grow. When cultures are initiated at cell densities where growth occurs in the absence of added cytokinins only after a long lag phase, the addition of cytokinins reduces the length of the lag phase. In these effects zeatin is fully effective at much lower concentrations than kinetin. As the duration of stationary phase is increased in the stock cultures, the ability of the cells to grow from a low initial cell density declines. This appears to be due to their declining endogenous cytokinin activity and declining ability to take up added cytokinin from their culture medium. It is postulated that, during the lag phase, the cells develop a critical level of cytokinin activity by an excess of endogenous synthesis over loss to the culture medium and internal degradation. When the phase of cell division has been initiated, the subsequent growth of the cultures is unaffected by low external levels of cytokinins.

Hormones in Plants Bearing Nitrogen-fixing Root Nodules: Distribution and Seasonal Changes in Levels of Cytokinins in Alnus glutinosa (L.) Gaertn

Abstract: The root nodules of both dormant and non-dormant plants of Alnus glutinosa (L.) Gaertn. were found (by the soybean callus bioassay) to contain levels of cytokinin activity greatly exceeding those of other parts of young vegetative plants. A large, transient increase in cytokinin activity occurred in the nodules at the time of bud break. Similar, although much smaller, increases were detected also in roots and buds. The increase in the level of nodule cytokinin activity was observed both in mature trees and in young pot-grown plants in two successive years. A second peak of cytokinin activity, considered to be derived from cytokinin nucleotides, was found in the nodules of mature trees in mid summer. Analysis of cytokinin extracts of different plant parts by means of a Sephadex LH20 column revealed the presence of three main peaks of activity, with elution volumes corresponding to those of zeatin-9-glucoside, zeatin riboside, and zeatin. While the glucoside-like peak was predominant in the nodules and leaves it was not detected in root pressure sap. A zeatin ribo side-like peak was the major cytokinin in the roots and root pressure sap. These findings are discussed in relation to current hypotheses concerning the production, distribution, and possible physiological roles of the cytokinins.