title: Light Controls Cytokinin Signaling via Transcriptional Regulation of Constitutively Active Sensor Histidine Kinase CKI1.
abstract: In plants, the multistep phosphorelay (MSP) pathway mediates a range of regulatory processes, including those activated by cytokinins. The cross talk between cytokinin response and light has been known for a long time. However, the molecular mechanism underlying the interaction between light and cytokinin signaling remains elusive. In the screen for upstream regulators we identified aLONG PALE HYPOCOTYL(LPH) gene whose activity is indispensable for spatiotemporally correct expression ofCYTOKININ INDEPENDENT1(CKI1), encoding the constitutively active sensor His kinase that activates MSP signaling.lphis a new allele ofHEME OXYGENASE1(HY1) that encodes the key protein in the biosynthesis of phytochromobilin, a cofactor of photoconvertible phytochromes. Our analysis confirmed the light-dependent regulation of theCKI1expression pattern. We show thatCKI1expression is under the control of phytochrome A (phyA), functioning as a dual (both positive and negative) regulator ofCKI1expression, presumably via the phyA-regulated transcription factors (TF) PHYTOCHROME INTERACTING FACTOR3 and CIRCADIAN CLOCK ASSOCIATED1. Changes inCKI1expression observed inlph/hy1-7andphymutants correlate with misregulation of MSP signaling, changed cytokinin sensitivity, and developmental aberrations that were previously shown to be associated with cytokinin and/or CKI1 action. Besides that, we demonstrate a novel role of phyA-dependentCKI1expression in the hypocotyl elongation and hook development during skotomorphogenesis. Based on these results, we propose that the light-dependent regulation ofCKI1provides a plausible mechanistic link underlying the well-known interaction between light- and cytokinin-controlled plant development.
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.).
authors.forename: Tereza
authors.identifier: http://orcid.org/0000-0002-6051-6944
authors.initials: T
authors.lastname: Dobisova
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.).
authors.forename: Vendula
authors.initials: V
authors.lastname: Hrdinova
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.).
authors.forename: Candela
authors.initials: C
authors.lastname: Cuesta
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.).
authors.forename: Sarka
authors.initials: S
authors.lastname: Michlickova
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.).
authors.forename: Ivana
authors.initials: I
authors.lastname: Urbankova
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.).
authors.forename: Romana
authors.initials: R
authors.lastname: Hejatkova
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.).
authors.forename: Petra
authors.identifier: http://orcid.org/0000-0002-5949-0724
authors.initials: P
authors.lastname: Zadnikova
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.).
authors.forename: Marketa
authors.identifier: http://orcid.org/0000-0002-5803-2879
authors.initials: M
authors.lastname: Pernisova
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.).
authors.forename: Eva
authors.initials: E
authors.lastname: Benkova
authors.affiliation: CEITEC - Central European Institute of Technology and National Centre for Biomolecular Research, Masaryk University, CZ-62500, Brno, Czech Republic (T.D., V.H., S.M., I.U., R.H., P.Z., M.P., E.B., J.H.); and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria (C.C., P.Z., E.B.) hejatko@sci.muni.cz.
authors.forename: Jan
authors.identifier: http://orcid.org/0000-0002-2622-6046
authors.initials: J
authors.lastname: Hejatko
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000528:radiation effects*; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism; D018546:Hypocotyl / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D008027:Light; D008957:Models, Genetic; D009154:Mutation; D051942:Phytochrome A / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000528:radiation effects*
chemical_list: D029681:Arabidopsis Proteins; D003583:Cytokinins; D051942:Phytochrome A; C585690:HY1 protein, Arabidopsis; D006419:Heme Oxygenase (Decyclizing); D011494:Protein Kinases; C101990:CKI1 protein, Arabidopsis