Cytokinin <i>N</i>-glucosides: Occurrence, Metabolism and Biological Activities in Plants
Eva Pokorná,
Tomáš Hluska,
Petr Galuszka,
H. Tucker Hallmark,
Petre I. Dobrev,
Lenka Záveská Drábková,
Tomáš Filipi,
Katarína Holubová,
Ondřej Plíhal,
Aaron M. Rashotte,
Roberta Filepová,
Jiří Malbeck,
Ondřej Novák,
Lukáš Spíchal,
Břetislav Brzobohatý,
Pavel Mazura,
Lenka Zahajská,
Václav Motyka
Affiliations
Eva Pokorná
Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02 Prague 6, Czech Republic
Tomáš Hluska
Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02 Prague 6, Czech Republic
Petr Galuszka
Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic
H. Tucker Hallmark
Department of Biological Science, Auburn University, Auburn, AL 36849, USA
Petre I. Dobrev
Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02 Prague 6, Czech Republic
Lenka Záveská Drábková
Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02 Prague 6, Czech Republic
Tomáš Filipi
Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Zemědělská 1665/1, 613 00 Brno, Czech Republic
Katarína Holubová
Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic
Ondřej Plíhal
Laboratory of Growth Regulators, Institute of Experimental Botany of the Czech Academy of Sciences and Faculty of Science of Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic
Aaron M. Rashotte
Department of Biological Science, Auburn University, Auburn, AL 36849, USA
Roberta Filepová
Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02 Prague 6, Czech Republic
Jiří Malbeck
Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02 Prague 6, Czech Republic
Ondřej Novák
Laboratory of Growth Regulators, Institute of Experimental Botany of the Czech Academy of Sciences and Faculty of Science of Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic
Lukáš Spíchal
Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic
Břetislav Brzobohatý
Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Zemědělská 1665/1, 613 00 Brno, Czech Republic
Pavel Mazura
Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Zemědělská 1665/1, 613 00 Brno, Czech Republic
Lenka Zahajská
Isotope Laboratory, Institute of Experimental Botany of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague 4, Czech Republic
Václav Motyka
Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojová 263, 165 02 Prague 6, Czech Republic
Cytokinins (CKs) are a class of phytohormones affecting many aspects of plant growth and development. In the complex process of CK homeostasis in plants, N-glucosylation represents one of the essential metabolic pathways. Its products, CK N7- and N9-glucosides, have been largely overlooked in the past as irreversible and inactive CK products lacking any relevant physiological impact. In this work, we report a widespread distribution of CK N-glucosides across the plant kingdom proceeding from evolutionary older to younger plants with different proportions between N7- and N9-glucosides in the total CK pool. We show dramatic changes in their profiles as well as in expression levels of the UGT76C1 and UGT76C2 genes during Arabidopsis ontogenesis. We also demonstrate specific physiological effects of CK N-glucosides in CK bioassays including their antisenescent activities, inhibitory effects on root development, and activation of the CK signaling pathway visualized by the CK-responsive YFP reporter line, TCSv2::3XVENUS. Last but not least, we present the considerable impact of CK N7- and N9-glucosides on the expression of CK-related genes in maize and their stimulatory effects on CK oxidase/dehydrogenase activity in oats. Our findings revise the apparent irreversibility and inactivity of CK N7- and N9-glucosides and indicate their involvement in CK evolution while suggesting their unique function(s) in plants.