Distinct metabolism of N-glucosides of isopentenyladenine and trans-zeatin determines cytokinin metabolic spectrum in Arabidopsis

0522232 - ÚEB 2020 RIV GB eng J - Journal Article
Hošek, Petr - Hoyerová, Klára - Kiran, Nagavalli S. - Dobrev, Petre - Zahajská, Lenka - Filepová, Roberta - Motyka, Václav - Müller, Karel - Kamínek, Miroslav
Distinct metabolism of N-glucosides of isopentenyladenine and trans-zeatin determines cytokinin metabolic spectrum in Arabidopsis.
New Phytologist. Roč. 225, mar (2020), s. 2423-2438. ISSN 0028-646X. E-ISSN 1469-8137
R&D Projects: GA ČR(CZ) GA16-19557S; GA ČR(CZ) GA19-12262S; GA MŠMT(CZ) EF16_019/0000738
Institutional support: RVO:61389030
Keywords : Arabidopsis thaliana * UGT * cytokinin N-glucoside
OECD category: Biochemical research methods
Impact factor: 10.152, year: 2020
Method of publishing: Open access
http://dx.doi.org/10.1111/nph.16310

The diversity of cytokinin (CK) metabolites suggests their interconversions are the predominant regulatory mechanism of CK action. Nevertheless, little is known about their directionality and kinetics in planta. CK metabolite levels were measured in 2-wk-old Arabidopsis thaliana plants at several time points up to 100 min following exogenous application of selected CKs. The data were then evaluated qualitatively and by mathematical modeling. Apart from elevated levels of trans-zeatin (tZ) metabolites upon application of N6 -(Δ2 -isopentenyl)adenine (iP), we observed no conversions between the individual CK-types - iP, tZ, dihydrozeatin (DHZ) and cis-zeatin (cZ). In particular, there was no sign of isomerization between tZ and cZ families. Also, no increase of DHZ-type CKs was observed after application of tZ, suggesting low baseline activity of zeatin reductase. Among N-glucosides, those of iP were not converted back to iP while tZ N-glucosides were cleaved to tZ bases, thus affecting the whole metabolic spectrum. We present the first large-scale study of short-term CK metabolism kinetics and show that tZ N7- and N9-glucosides are metabolized in vivo. We thus refute the generally accepted hypothesis that N-glucosylation irreversibly inactivates CKs. The subsequently constructed mathematical model provides estimates of the metabolic conversion rates.
Permanent Link: http://hdl.handle.net/11104/0306758