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.

Changes in leucyl, seryl, and tyrosyl tRNAs in aging soybean cotyledons

Abstract: Application of different concentrations of the naturally occurring cytokinin zeatin 6(4-hydroxy-3-methyl trans-2-butenylamino)purine caused changes in one or more species of tRNAs. With the depletion of storage products from senescing cotyledons quantitative changes in tRNAleu1, 5, 6, tRNAser1–3, and tRNAtyr1–4 were observed. Higher concentrations of zeatin applied as a single spray did not produce significant changes either in the cotyledon or the hypocotyl. The relationship of cytokinin activity to senescing soybean cotyledons is discussed.

Repetitive somatic embryogenesis from leaves of the medicinal plant Petiveria alliacea L.

Abstract: Leaf segments from in vitro-grown shoot cultures of Petiveria alliacea were incubated on Murashige and Skoog (MS) medium supplemented with different concentrations of zeatin, thidiazuron, 2,4-dichlorophenoxyacetic acid (2,4-D) or picloram (PIC). Direct somatic embryogenesis was induced in response to all tested concentrations of 2,4-D and PIC. Primary somatic embryos displayed highly repetitive embryogenesis, both on the induction medium and in liquid hormone-free MS medium. Plantlets were obtained from these secondary embryos at an estimated frequency of 5 %, after 180 days of culture on half-strength MS medium gelled with 0.2 % Phytagel. Simultaneous development of friable non-embryogenic callus was also observed on media containing PIC or 2,4-D at different concentrations. Cell suspension cultures initiated from these callus tissues did not show an increase in biomass. The embryogenic portions formed at the surface of the explants in response to 20.0 μM PIC were inoculated in hormone-free full-or half-strength liquid MS medium (MS0) and showed high rates of secondary embryogenesis, resulting in the production of a mean of 35 embryos for each embryo inoculated at the culture initiation. Embryos that started the conversion process in the liquid MS0 medium originated whole plants at a frequency of 100 % when transferred to MS0 medium solidified with 0.7 % agar. Acclimatization was achieved in 90 % of the converted plantlets, with the production of phenotypically normal plants. This system is potentially useful for the micropropagation of this species, as well as for the production of substances with pharmacological interest, such as dibenzyl trisulfide.

Cytokinin Production by Rhizobia

Abstract: Culture media from a number of rhizobial strains, including the type-strains of 8 major cross-inoculation groups, were analyzed for cytokinin content. Cytokinins were partially purified by chromatography on Amberlite XAD-2, then on Sephadex LH-20. The tobacco callus assay, HPLC and/or immunoassay were used for cytokinin analysis. All strains of rhizobia examined produced at least 2 cytokinin-active compounds, with total cytokinin activity ranging from 1 to several µg kinetin equivalents per liter of culture filtrate. There were both qualitative and quantitative differences between rhizobial species. The cytokinin profiles of most strains included zeatin or its derivatives. Addition of adenine, seed extract or flavonoid inducers to the culture medium altered cytokinin synthesis. Preliminary genetic data do not support nod gene involvement in cytokinin synthesis under noninducing conditions. Growth pouch experiments showed increased nodulation of soybean plants treated with trans-zeatin.