Ectopic over-expression of the maize beta-glucosidase Zm-p60.1 perturbs cytokinin homeostasis in transgenic tobacco

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...

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Veröffentlicht in:Journal of experimental botany. - 1985. - 57(2006), 4 vom: 01., Seite 985-96
1. Verfasser: Kiran, Nagavalli S (VerfasserIn)
Weitere Verfasser: Polanská, Lenka, Fohlerová, Radka, Mazura, Pavel, Válková, Martina, Smeral, Miloslav, Zouhar, Jan, Malbeck, Jirí, Dobrev, Petre I, Machácková, Ivana, Brzobohaty, Bretislav
Format: Aufsatz
Sprache:English
Veröffentlicht: 2006
Zugriff auf das übergeordnete Werk:Journal of experimental botany
Schlagworte:Journal Article Research Support, Non-U.S. Gov't Culture Media Cytokinins Indoleacetic Acids Abscisic Acid 72S9A8J5GW Zeatin 7I6OOJ9GR6 beta-Glucosidase EC 3.2.1.21
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100 1 |a Kiran, Nagavalli S  |e verfasserin  |4 aut 
245 1 0 |a Ectopic over-expression of the maize beta-glucosidase Zm-p60.1 perturbs cytokinin homeostasis in transgenic tobacco 
264 1 |c 2006 
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500 |a Date Revised 13.12.2023 
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520 |a 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-p60.1, a maize beta-glucosidase capable of releasing active cytokinins from O- and N3-glucosides, to analyse its potential to perturb zeatin metabolism in planta. Zm-p60.1 in chloroplasts isolated from transgenic leaves has an apparent K(m) more than 10-fold lower than the purified enzyme in vitro. Adult transgenic plants grown in the absence of exogenous zeatin were morphologically indistinguishable from the wild type although differences in phytohormone levels were observed. When grown on medium containing zeatin, inhibition of root elongation was apparent in all seedlings 14 d after sowing (DAS). Between 14 and 21 DAS, the transgenic seedlings accumulated fresh weight leading later (28-32 DAS) to ectopic growths at the base of the hypocotyl. The development of ectopic structures correlated with the presence of the enzyme as demonstrated by histochemical staining. Cytokinin quantification showed that transgenic seedlings grown on medium containing zeatin accumulate active metabolites like zeatin riboside and zeatin riboside phosphate and this might lead to the observed changes. The presence of the enzyme around the base of the hypocotyl and later, in the ectopic structures themselves, suggests that the development of these structures is due to the perturbance in zeatin metabolism caused by the ectopic presence of Zm-p60.1 
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700 1 |a Polanská, Lenka  |e verfasserin  |4 aut 
700 1 |a Fohlerová, Radka  |e verfasserin  |4 aut 
700 1 |a Mazura, Pavel  |e verfasserin  |4 aut 
700 1 |a Válková, Martina  |e verfasserin  |4 aut 
700 1 |a Smeral, Miloslav  |e verfasserin  |4 aut 
700 1 |a Zouhar, Jan  |e verfasserin  |4 aut 
700 1 |a Malbeck, Jirí  |e verfasserin  |4 aut 
700 1 |a Dobrev, Petre I  |e verfasserin  |4 aut 
700 1 |a Machácková, Ivana  |e verfasserin  |4 aut 
700 1 |a Brzobohaty, Bretislav  |e verfasserin  |4 aut 
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