Topic
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.
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TL;DR: Zeatin O-glycosyltransferase may be involved in modulation of cytokinins under cold stress, and was detected in the nucleus, cytoplasm, and closely associated with the plasma membrane and in the cell wall of Z. mays root cells.
Abstract: Zeatin O-glycosides have been reported as inactive and stable storage forms of cytokinins whose concentrations increase in cold stressed plants. Zeatin O-glycosides accumulation in developing bean seeds has been correlated with an increase of zeatin O-glycosyltransferase , which is specific to trans-zeatin, and catalyzes the conjugation of zeatin O-glycosides. When Phaseolus vulgaris and Zea mays seedlings were grown for 3 days at 25 and then incubated at 4 or 10 for 6 days no further growth was observed in roots. Hypertrophy was observed in the root tips of both species. In shoot-hypocotyl complexes, in contrast, growth occurred when seedlings were incubated at 10 . Western analysis, with Mabs specific to zeatin O-glycosyltransferase, detected antigenically related proteins in roots, shoot tips and cotyledons after seedlings were cold stressed for 1–6 days at 4 or 10 . Immunolocalization, of both maize and bean root sections grown at 25 revealed antigenically related proteins that were detected at low levels in cortical cells. The signal intensified upon cold stress. The localization of zeatin O-glycosyltransferase in Z. mays root tips was directly comparable to the distribution of the zeatin O-glycosides. The enzyme was detected in the nucleus, cytoplasm, and closely associated with the plasma membrane and in the cell wall of Z. mays root cells. Southern analysis suggested that more than one gene in Z. mays that were homologous to zeatin O-glycosyltransferase in P. vulgaris. Zeatin O-glycosyltransferase may be involved in modulation of cytokinins under cold stress.
17 citations
TL;DR: Both IAA and zeatin led to an expansion of the lipid monolayer caused by electrostatic interactions between oppositely charged groups: negatively charged polar group of DMPS and positively chargedZeatin or positive DPTAP headgroup and negative IAA.
Abstract: In this study, the influence of plant hormones, negatively charged indolilo-3-acetic acid (IAA) and positively charged zeatin, on lipid membranes was studied. As models of negatively and positively charged biological membranes, monolayers of 1,2-dimyristoyl-sn-glycero-3-[phospho-l-serine] (DMPS) and 1,2-dipalmitoyl-3-trimethylammonium-propane (DPTAP) at the water/air interface were used, respectively. Additionally, the effect of cadmium and selenium ions on the interactions between hormones and lipids was studied. Surface pressure and surface potential measurements, Brewster angle microscopy (BAM), and grazing incidence X-ray diffraction (GIXD) were used for that purpose. Both IAA and zeatin led to an expansion of the lipid monolayer caused by electrostatic interactions between oppositely charged groups: negatively charged polar group of DMPS and positively charged zeatin or positive DPTAP headgroup and negative IAA. The addition of ions to the subphase containing hormones causes competitive interactions of both solutes with oppositely charged lipid polar heads. The largest effect was observed for IAA. While zeatin does not change the domain shape of DMPS, IAA causes the complete disappearance of characteristic DPTAP domains. Addition of SeO(4)(2-) ions causes restoration of DPTAP domains observed on pure water.
17 citations
TL;DR: The lower parts of the cotyledon excised at the plumule base were found to display a markedly enhanced production of adventitious shoots compared to other cotYledon regions.
Abstract: An efficient plant regeneration system has been developed for figleaf gourd (Cucurbita ficifolia Bouche), which is exclusively used as a rootstock for cucumber. The protocol is based on results obtained from a series of culture experiments involving different parts of the cotyledons and various media. The culture of cotyledon explants was critical for the enhancement of shoot regeneration frequency. The lower parts of the cotyledon excised at the plumule base were found to display a markedly enhanced production of adventitious shoots compared to other cotyledon regions. Culture in silver nitrate-supplemented Murashige and Skoog (MS) medium was not beneficial for shoot regeneration and suppressed root regeneration. Efficient shoot regeneration was obtained on MS medium containing 1.0 mg l−1 zeatin and 0.1 mg l−1 indole-3-acetic acid. Regenerated shoots successfully elongated and rooted in medium containing 0.1 mg l−1 1-naphthaleneacetic acid after 10–15 days of subculturing. The plantlets were satisfactorily acclimatized in a greenhouse and grew into normal plants without any morphological alterations.
17 citations
TL;DR: Pollen embryogenesis and subsequent plant regeneration have been established from cultured whole barley spikes in agitated N6 liquid medium containing high levels of 2,4-D, Ficoll and potato extract.
Abstract: Pollen embryogenesis and subsequent plant regeneration have been established from cultured whole barley spikes in agitated N6 liquid medium (Chu 1978) containing high levels of 2,4-D, Ficoll and potato extract. Microspore division within the anthers and subsequent embryogenic development were obtained in medium containing high amounts of reduced nitrogen with Zeatin, NAA and BAP (all at 0.5 mg/l levels, pH 6.2). Once embryoids were formed in the liquid medium, they produced secondary embryoids from the scutellum and subsequently plants on MS (Murashige and Skoog 1962) agar medium containing BAP and NAA. The ratio of green plants to albino was 1∶8.7.
17 citations
TL;DR: It is concluded that a reduced level of cytokinins in the lateral suppressor (ls) mutant of tomato shoots is not responsible for the absence of axillary meristem formation.
Abstract: We studied axillary meristem formation of the lateral suppressor (ls) mutant of tomato after elevating the endogenous cytokinin levels through introduction of the isopentenyltransferase (ipt) gene from Agrobacterium tumefaciens Growth and development of several transformants were examined during in vitro culture Transformants exhibited phenotypes varying in severity and were divided into four classes A number of the ipt transformants had a normal phenotype, as non-transformed plants Others showed a mild to severe ‘cytokinin-like’ phenotype Transformants with a mild phenotype exhibited reduced internode length and reduced root development Transformants with a severe phenotype showed even shorter internodes, loss of apical dominance, reduction of leaf size, production of callus at the basis of the shoots and absence of root development or development of green non-branching roots The severity of the phenotype correlated well with the level of ipt gene expression, as measured by northern analysis Transformants with a severe phenotype also exhibited increased levels of zeatin riboside, but zeatin levels were not elevated The increase in endogenous zeatin riboside levels in the ls mutant did not restore axillary meristem formation, but sometimes bulbous structures were formed in the initially ‘empty’ leaf axils Several adventitious meristems and shoots developed from below the surface of these structures It is concluded that a reduced level of cytokinins in the ls mutant shoots is not responsible for the absence of axillary meristem formation
17 citations