caa a22 4500 463171810 CHVBK 20180406164815.0 cr unu---uuuuu 170326e20070901xx s 000 0 eng 10.1007/s00344-007-9011-x doi (NATIONALLICENCE)springer-10.1007/s00344-007-9011-x Cytokinin Regulation of Gene Expression in the AHP Gene Family in Arabidopsis thaliana [Elektronische Daten] [Jana Hradilová, Jiří Malbeck, Břetislav Brzobohatý] In higher plants histidine-aspartate phosphorelays are involved in hormone and stress signaling via a two-component system of signal transduction. In this system a histidine-containing phosphotransmitter (HPt) mediates signal transmission from a sensory histidine kinase to a response regulator, providing integration and/or branching of several different signaling pathways. Five genes encoding HPts, AHP1-5, have been identified in Arabidopsis. Histidine-aspartate phosphorelays involving HPts have been at least partly implicated in cytokinin signaling. We analyzed the regulation by cytokinins of AHP gene expression. We compared the effects on steady-state levels of AHP transcripts of a short-term treatment with an aromatic cytokinin and increase in endogenous isoprenoid cytokinin levels using an activable ipt system in 8-day-old Arabidopsis seedlings. Following ipt activation, a rapid and highly preferential increase in trans-zeatin-type cytokinins was observed, whereas other isoprenoid-type cytokinins showed no or only marginal increases. The levels of cytokinin metabolites under long-term ipt activation suggest that the seedlings may have difficulties in efficiently downregulating active forms of the hormone. Using real-time RT-PCR, transient increases in steady-state levels of AHP1-4 transcripts in response to both the short-term N 6-benzyladenine treatment and the increase in endogenous trans-zeatin-type cytokinin levels were observed. In contrast, both the full and the alternatively spliced AHP5 transcripts remained unaltered. On the other hand, increases in steady-state levels of AHP1-4 transcripts observed in seedlings cultivated continuously in the presence of exogenous N 6-benzyladenine were not paralleled in seedlings with constitutively increased endogenous trans-zeatin-type cytokinins, providing further indirect evidence for distinct functions of aromatic and isoprenoid cytokinins. Springer Science+Business Media, LLC, 2007 Gene expression nationallicence AHP gene family nationallicence Cytokinin signal transduction nationallicence Cytokinin metabolism nationallicence Isopentenyl transferase nationallicence Hradilová Jana Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, CZ-61265, Brno, Czech Republic aut Malbeck Jiří Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 135, CZ-16502, Prague, Czech Republic aut Brzobohatý Břetislav Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, CZ-61265, Brno, Czech Republic aut Journal of Plant Growth Regulation Springer-Verlag 26/3(2007-09-01), 229-244 0721-7595 26:3<229 2007 26 344 https://doi.org/10.1007/s00344-007-9011-x text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00344-007-9011-x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hradilová Jana Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, CZ-61265, Brno, Czech Republic aut NATIONALLICENCE 700 1- Malbeck Jiří Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 135, CZ-16502, Prague, Czech Republic aut NATIONALLICENCE 700 1- Brzobohatý Břetislav Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, CZ-61265, Brno, Czech Republic aut NATIONALLICENCE 773 0- Journal of Plant Growth Regulation Springer-Verlag 26/3(2007-09-01), 229-244 0721-7595 26:3<229 2007 26 344 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer