Cytokinin translocation and metabolism in lupin species II. New nucleotide metabolites of cytokinins

Letham, D. S.; Zhang, R.

doi:10.1016/0168-9452(89)90020-4

Cited by 19 publications

(8 citation statements)

References 8 publications

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“…The chromatographic characteristics of compounds A and B suggest that these metabolites may be O ‐acetyl‐ZRMP and O ‐acetyl‐ZR, respectively, both of which have previously been detected in another legume, Lupinus angustifolius , after feeding with radiolabelled ZR (Jameson et al. 1987, Letham and Zhang 1989).…”

Section: Discussionmentioning

confidence: 82%

Transport and metabolism of xylem cytokinins during lateral bud release in decapitated chickpea (Cicer arietinum) seedlings

Mader

Turnbull

Emery

2003

Physiologia Plantarum

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Although cytokinins (CKs) are widely thought to have a role in promoting shoot branching, there is little data supporting a causative or even a correlative relationship between endogenous CKs and timing of bud outgrowth. We previously showed that lateral bud CK content increased rapidly following shoot decapitation. However, it is not known whether roots are the source of this CK. Here, we have used shoot decapitation to instantaneously induce lateral bud release in chickpea seedlings. This treatment rapidly alters rate and direction of solvent and solute (including CK) trafficking, which may be a passive signalling mechanism central to initiation of lateral bud release. To evaluate changes in xylem transport, intact and decapitated plants were infiltrated with [3H]zeatin riboside ([3H]ZR), a water‐soluble blue dye or [3H]H2O by injection into the hypocotyl. All three tracers were recovered in virtually all parts of the shoot within 1 h of injection. In intact plants, solute accumulation in the lateral bud at node 1 was significantly less than in the adjacent stipule and nodal tissue. In decapitated plants, accumulation of [3H]ZR and of blue dye in the same bud position was increased 3‐ to 10‐fold relative to intact plants, whereas content of [3H]H2O was greatly reduced indicating an increased solvent throughput. The stipule and cut stem, predicted to have high evapotranspiration rates, also showed increased solute content accompanied by enhanced depletion of [3H]H2O. To assess whether metabolism modifies quantities of active CK reaching the buds, we followed the metabolic fate of [3H]ZR injected at physiological concentrations. Within 1 h, 80–95% of [3H]ZR was converted to other active CKs (mainly zeatin riboside‐5′phosphate (ZRMP) and zeatin (Z)), other significant, but unconfirmed metabolites some of which may be active (O‐acetylZR, O‐acetylZRMP and a compound correlated with sites of high CK‐concentrations) and inactive catabolites (adenosine, adenine, 5′AMP and water). Despite rapid metabolic degradation, the total active label, which was indicative of CK concentration in buds, increased rapidly following decapitation. It can be inferred that xylem sap CKs represent one source of active CKs appearing in lateral buds after shoot decapitation.

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Section: Discussionmentioning

confidence: 82%

Transport and metabolism of xylem cytokinins during lateral bud release in decapitated chickpea (Cicer arietinum) seedlings

Mader

Turnbull

Emery

2003

Physiologia Plantarum

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“…It has been demonstrated many times that exogenously applied free cytokinin bases are rapidly metabolized into the corresponding nucleosides and nucleotides (e.g. Sondheimer and Tzou, 1971;Letham and Zhang, 1989;Suttle and Banowetz, 2000). Reverse phosphorylation of nucleosides to nucleotides could be catalyzed by adenosine kinase (EC 2.7.1.20), as was shown for the recombinant enzyme from the moss P. patents (von Schwartzenberg et al, 1998).…”

Section: 'Lonely Guy' and Phosphatases Activate Cytokinin Nucleotidesmentioning

confidence: 96%

Evolution of cytokinin biosynthesis and degradation

Frébort

Kowalska

Hluska

et al. 2011

Journal of Experimental Botany

358

283

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Cytokinin hormones are important regulators of development and environmental responses of plants that execute their action via the molecular machinery of signal perception and transduction. The limiting step of the whole process is the availability of the hormone in suitable concentrations in the right place and at the right time to interact with the specific receptor. Hence, the hormone concentrations in individual tissues, cells, and organelles must be properly maintained by biosynthetic and metabolic enzymes. Although there are merely two active cytokinins, isopentenyladenine and its hydroxylated derivative zeatin, a variety of conjugates they may form and the number of enzymes/isozymes with varying substrate specificity involved in their biosynthesis and conversion gives the plant a variety of tools for fine tuning of the hormone level. Recent genome-wide studies revealed the existence of the respective coding genes and gene families in plants and in some bacteria. This review summarizes present knowledge on the enzymes that synthesize cytokinins, form cytokinin conjugates, and carry out irreversible elimination of the hormones, including their phylogenetic analysis and possible variations in different organisms.

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“…In recent years, cisZ was also detected in algae (Stirk and others 2003) and bryophytes (Von Schwartzenberg and others 2007), (Záveská Drábková andothers others 2007, Záveská Drábková andothers 2015). Most of the physiological activity of CKs is attributed to free bases (Lomin and others 2015;Hothorn and others 2011), and numerous investigations showed that exogenously applied CK-free bases were rapidly metabolized into the corresponding ribotide and riboside forms in plant tissues (Singh and others 1988;Letham and Zhang 1989;Moffatt and others 1991;Yonekura-Sakakibara and others 2004). Cytokinin ribosides and nucleotides, although do not bind to CK receptors (Hothorn and others 2011), can easily be converted in plant tissues to free bases (a two-step and a single-step pathway of cytokinin activation) that can bind to specific receptors (Kamada-Nobusada and Sakakibara 2009).…”

Section: Stress Hormonesmentioning

confidence: 97%

Endogenous Phytohormones in Spontaneously Regenerated Centaurium erythraea Rafn. Plants Grown In Vitro

Trifunović‐Momčilov

Motyka

Dragićević

et al. 2015

J Plant Growth Regul

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Phytohormones are important regulators of numerous developmental and physiological processes in plants. Spontaneous morphogenesis of the common centaury (Centaurium erythraea Rafn.) is possible on nutrition medium without addition of any plant growth regulator depending solely on endogenous phytohormone levels. Thus, this plant species represents a very good model system for the investigation of numerous physiological processes under phytohormonal control in vitro. We analysed the total amount of endogenous cytokinins (CKs) including the contents of their individual groups in shoots and roots of C. erythraea plants grown in vitro. The total amount of endogenous CKs was 1.4 times higher in shoots than in roots. Inactive or weakly active N-glucosides found to predominate in both organs of centaury plants, whereas free bases and O-glucosides represented only a small portion of the total CK pool. Consequently, centaury roots showed higher IAA content as well as IAA/ free CK base ratios compared to shoots. Centaury tissues also showed increased levels of ''stress hormones''. In contrast to SA, considerably higher levels of ABA were found in centaury shoots than in roots. Our results could serve as a basis for understanding and elucidating spontaneous de novo shoot organogenesis and further plant regeneration of C. erythraea in vitro. Abbreviations for CKs Adopted and Modified According to Kamínek and Others (2000) ADPAdenosine diphosphate AMP Adenosine monophosphate CK Cytokinin cisZ cis-zeatin cisZ7G cis-zeatin 7-glucoside cisZ9G cis-zeatin 9-glucoside cisZOG cis-zeatin O-glucoside cisZR cis-zeatin 9-riboside cisZRMP cis-zeatin 9-riboside-5 0 -monophosphate cisZROG cis-zeatin 9-riboside O-glucoside DHZ Dihydrozeatin DHZ7GDihydrozeatin 7-glucoside DHZ9GDihydrozeatin 9-glucoside DHZOG Dihydrozeatin O-glucoside DHZR Dihydrozeatin 9-riboside DHZRMP Dihydrozeatin 9-riboside-5 0 -monophosphate DHZROG Dihydrozeatin 9-riboside O-glucoside iP N 6 -(D 2 -isopentenyl)adenine iP7G N 6 -(D 2 -isopentenyl)adenine 7-glucoside iP9G N 6 -(D 2 -isopentenyl)adenine 9-glucoside iPR N 6 -(D 2 -isopentenyl)adenine 9-riboside Milana Trifunović-Momčilov and Václav Motyka have contributed equally to this work. Electronic supplementary materialThe online version of this article (iPRMP N 6 -(D 2 -isopentenyl)adenine 9-riboside-5 0 -monophosphate transZ trans-zeatin transZ7Gtrans-zeatin 7-glucoside transZ9G trans-zeatin 9-glucoside transZOG trans-zeatin O-glucoside transZR trans-zeatin 9-riboside transZRMP trans-zeatin 9-riboside-5 0 -monophosphate transZROG trans-zeatin 9-riboside O-glucoside

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Cytokinin translocation and metabolism in lupin species II. New nucleotide metabolites of cytokinins

Cited by 19 publications

References 8 publications

Transport and metabolism of xylem cytokinins during lateral bud release in decapitated chickpea (Cicer arietinum) seedlings

Transport and metabolism of xylem cytokinins during lateral bud release in decapitated chickpea (Cicer arietinum) seedlings

Evolution of cytokinin biosynthesis and degradation

Endogenous Phytohormones in Spontaneously Regenerated Centaurium erythraea Rafn. Plants Grown In Vitro

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