Ultraviolet (UV) irradiation induces the expression of matrix metalloproteinases (MMPs), disturbing the metabolism of extracellular matrix (ECM), and causes the characteristic changes of photoaging in skin. Inhibition of induction of MMPs is suggested to alleviate photoaging induced by UV irradiation. Zeatin, purified from Zea mays, is a member of the cytokinin group of plant growth factors, th...

Although cytokinins (CKs) affect a number of processes connected with chloroplasts, it has never been rigorously proven that chloroplasts contain CKs. We isolated intact chloroplasts from tobacco (Nicotiana tabacum L. cv SR1) and wheat (Triticum aestivum L. cv Ritmo) leaves and determined their CKs by liquid chromatography/tandem mass spectroscopy. Chloroplasts from both species contained a who...

Investigation of the conversion of exogenous cis-zeatin to trans-zeatin in immature seeds of Phaseolus vulgaris L. led to the isolation of a cis-trans-isomerase from the endosperm. The enzyme was purified more than 2000-fold by chromatography on a series of fast protein liquid chromatography (anion exchange, gel filtration, and hydrophobic interaction) and concanavalin A columns. The enzymic re...

The cytokinin complex of Datura innoxia Mill. crown gall tissue was purified by ion exchange, Sephadex LH-20 chromatography and reversed-phase high performance liquid chromatography. By gas chromatography-mass spectrometry using (2)H-labeled compounds, the following cytokinins were identified in the basic fraction eluting from a cation exchange column: zeatin, zeatin riboside, dihydrozeatin, di...

Geometric and position isomers of zeatin and of ribosylzeatin and other compounds closely related to zeatin have been tested in the tobacco (Nicotiana tabacum var. Wisconsin No. 38) bioassay. None was more active than zeatin itself. There was a much greater difference in activity (> 50-fold) between trans- and cis-zeatin than between trans-isozeatin [6-(4-hydroxy-2-methyl-trans-2-butenylamino) ...

Zeatin is the most active and ubiquitous form of the naturally occurring cytokinins. Glycosyl conjugates of zeatin are found in many plant tissues and are considered important for storage and protection against degradative enzymes. Two enzymes catalyzing the formation of O-glycosyl derivatives of zeatin have been characterized, O-glucosyltransferase and O-xylosyltransferase, occurring in seeds ...

The effects of abscisic acid, zeatin, and gibberellic acid on the development of somatic embryos from cultured cells of caraway (Carum carvi L.) were observed.Somatic embryos complete development on a basal medium without exogenous hormones, but some are subject to developmental abnormalities including malformed cotyledons and accessory embryos. Both zeatin and gibberellic acid, especially in c...

The activity of the phytohormone cytokinin depends on a complex interplay of factors such as its metabolism, transport, stability, and cellular/tissue localization. O-glucosides of zeatin-type cytokinins are postulated to be storage and/or transport forms, and are readily deglucosylated. Transgenic tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) plants were constructed over-expressing Zm-p6...

In order to optimize the micropropagation of Qare-Qat (Vaccinium arctostaphylus J.J.Sm), samples were collected from two regions of Iran (Asalem and Kelardasht). Anderson (AN) media containing different concentrations of zeatin (0, 0.5, 1, 2 and 4 mg L-1) and different levels of pH (4.5, 5 and 5.5) were compared. The in vitro shoots were transferred on AN media supplemented with zeatin (1 and 2...

In order to optimize the micropropagation of Qare-Qat (Vaccinium arctostaphylus J.J.Sm), samples were collected from two regions of Iran (Asalem and Kelardasht). Anderson (AN) media containing different concentrations of zeatin (0, 0.5, 1, 2 and 4 mg L-1) and different levels of pH (4.5, 5 and 5.5) were compared. The in vitro shoots were transferred on AN media supplemented with zeatin (1 and 2...