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.

The effect of cytokinins on shoot proliferation, secondary metabolite production and antioxidant potential in shoot cultures of Scutellaria alpina

Abstract: The present study evaluates the effects of various cytokinins on Scutellaria alpina shoot proliferation and production of polyphenolic metabolites (baicalin, wogonoside, luteolin, luteolin 7-O-glucoside, verbascoside). The shoots were induced from shoot tips on MS medium supplemented with IAA (indole-3-acetic acid, 0.57 µM) and various concentrations of 6-benzylaminopurine (BAP), kinetin, zeatin (1, 2, 4, 8 µM) or tidiazuron (TDZ) (0.2, 0.5, 1 µM). Among the cytokinins tested, BAP was the most effective for shoot induction, and the highest number of shoots (25 per explant) was achieved with 2 and 4 µM BAP. Maximum biomass production was also achieved on these media. Significantly higher baicalin, wogonoside and verbascoside contents were recorded in treatments containing cytokinins combined with 0.57 µM IAA, when compared to cytokinin-free medium. TDZ at a concentration of 0.5 µM was the most effective for polyphenol production. However, supplementation with cytokinins often results in the reduction of luteolin and its 7-O-glucoside production in the shoot culture of S. alpina. ABTS [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)] and ferric reducing antioxidant power assays were used to identify the antioxidant potential of methanolic extracts from shoots cultured in the presence of different types and concentrations of cytokinins. In both tests, the shoots from medium supplemented with 0.5 µM TDZ demonstrated the strongest antioxidant activity. The results indicate that higher polyphenolic content correlated with greater reducing power and antiradical efficiency.

Somatic embryogenesis in peanut: Influence of growth regulators and sugars

Abstract: Somatic embryogenesis and plant regeneration were induced from immature embryonal axes and immature cotyledons of peanut (Arachis hypogaea L. fastigata type cv JLM-1). Influence of different auxins, cytokinins and sugars on somatic embryogenesis from immature cotyledon explants was also investigated. Among the different auxins tested, 2,4-dichlorophenoxyacetic acid (2,4-d) was most effective, producing the highest frequency of responding cultures and highest average number of somatic embryos per responding culture, while dicamba, picloram, indolepropionic acid, α-naphthaleneacetic acid, 2,4,4-trichlorophenoxypropionic acid and α-naphthoxyacetic acid were also effective for embryogenesis. Indolebutyric acid, indoleacetic acid, p-chlorophenoxyacetic acid and trichlorophenoxyacetic acid were not beneficial. Among the four cytokinins tested, zeatin slightly enhanced the frequency of somatic embryogenesis, while kinetin, 6-γ-γ-dimethylallylaminopurine and benzyladenine were relatively inhibitory. Among the different carbon sources tested, sucrose was the best for embryo induction and at 6% sucrose the highest frequency of responding cultures and average number of somatic embryos per explant were obtained. For inducing embryogenesis from embryonal axes, 2,4-d was more effective than picloram. Highest plant conversion frequency from somatic embryos was obtained in presence of dicamba or NAA and using cotyledon explants.

Micropropagation of the Mediterranean tree Ceratonia siliqua

Abstract: An in vitro propagation protocol based on axillary bud proliferation has been developed for mature female trees of Ceratonia siliqua L. `Galhosa' and `Mulata'. Browning and contaminants were the major obstacles for culture establishment. Shoot culture initiation was greatly influenced by explanting season, with the highest survival percentage observed in spring. The cultivar, cytokinin type and concentration were the most important factors affecting shoot multiplication. The best multiple-shoot response was obtained with `Mulata' on Murashige and Skoog medium supplemented with 4.44 μM 6-benzyladenine or 4.56 μM zeatin. Rooting was achieved on growth-regulator-free medium after basal dipping of shoots in indole-3-butyric acid (4.9 mM). Plantlets were successfully acclimatized (80–85%) under high relative humidity and then moved to the glasshouse. A field trial was established to follow their agronomic behaviour.

An enzyme mediating the conversion of zeatin to dihydrozeatin in phaseolus embryos.

Abstract: A reductase catalyzing the conversion of zeatin to dihydrozeatin was detected in soluble fractions of immature Phaseolus vulgaris embryos. The enzyme was partially purified by ammonium sulfate fractionation and affinity, gel filtration, and anion exchange chromatography. NADPH was the only cofactor required for enzyme activity, and the pH optimum was 7.5 to 8.0. The enzyme did not recognize compounds closely related to zeatin, such as ribosylzeatin, cls-zeatin, O-xylosylzeatin, N6-(Δ2-isopentenyl)adenine, or N6-(Δ2-isopentenyl)adenosine. No conversion of dihydrozeatin to zeatin by the enzyme was observed. Two forms of the reductase could be separated by either gel filtration or anion exchange high performance liquid chromatography. The high molecular weight isozyme (Mr 55,000 ± 5,000) eluted as the second peak from the anion exchange column, while the low molecular weight isozyme (Mr 25,000± 5000) was less negatively charged. The results suggest that side chain reduction occurs at the free base level. In addition, Phaseolus embryos are useful for the detection of zeatin-specific metabolic enzymes.