title: Cytokinins Are Initial Targets of Light in the Control of Bud Outgrowth.
abstract: Bud outgrowth is controlled by environmental and endogenous factors. Through the use of the photosynthesis inhibitor norflurazon and of masking experiments, evidence is given here that light acts mainly as a morphogenic signal in the triggering of bud outgrowth and that initial steps in the light signaling pathway involve cytokinins (CKs). Indeed, in rose (Rosa hybrida), inhibition of bud outgrowth by darkness is suppressed solely by the application of CKs. In contrast, application of sugars has a limited effect. Exposure of plants to white light (WL) induces a rapid (after 3-6 h of WL exposure) up-regulation of CK synthesis (RhIPT3 and RhIPT5), of CK activation (RhLOG8), and of CK putative transporter RhPUP5 genes and to the repression of the CK degradation RhCKX1 gene in the node. This leads to the accumulation of CKs in the node within 6 h and in the bud at 24 h and to the triggering of bud outgrowth. Molecular analysis of genes involved in major mechanisms of bud outgrowth (strigolactone signaling [RwMAX2], metabolism and transport of auxin [RhPIN1, RhYUC1, and RhTAR1], regulation of sugar sink strength [RhVI, RhSUSY, RhSUC2, and RhSWEET10], and cell division and expansion [RhEXP and RhPCNA]) reveal that, when supplied in darkness, CKs up-regulate their expression as rapidly and as intensely as WL Additionally, up-regulation of CKs by WL promotes xylem flux toward the bud, as evidenced by Methylene Blue accumulation in the bud after CK treatment in the dark. Altogether, these results suggest that CKs are initial components of the light signaling pathway that controls the initiation of bud outgrowth.
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: Hanaé
authors.identifier: 0000-0002-8475-2976
authors.initials: H
authors.lastname: Roman
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: Tiffanie
authors.initials: T
authors.lastname: Girault
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: François
authors.initials: F
authors.lastname: Barbier
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: Thomas
authors.initials: T
authors.lastname: Péron
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: Nathalie
authors.identifier: 0000-0002-3248-0286
authors.initials: N
authors.lastname: Brouard
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: Aleš
authors.initials: A
authors.lastname: Pěnčík
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: Ondřej
authors.identifier: 0000-0003-3452-0154
authors.initials: O
authors.lastname: Novák
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: Alain
authors.identifier: 0000-0002-4785-7349
authors.initials: A
authors.lastname: Vian
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: Soulaiman
authors.initials: S
authors.lastname: Sakr
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: Jérémy
authors.initials: J
authors.lastname: Lothier
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.).
authors.forename: José
authors.identifier: 0000-0002-6200-0116
authors.initials: J
authors.lastname: Le Gourrierec
authors.affiliation: IRHS (Research Institute on Horticulture and Seeds), Université d'Angers, Agrocampus-Ouest, Institut National de la Recherche Agronomique, SFR 4207 QUASAV, 49070 Beaucouzé, France (H.R., T.G., F.B., T.P., N.B., A.V., S.S., J.L., J.L.G., N.L.); andLaboratory of Growth Regulators and Department of Chemical Biology and Genetics, Palacký University and Institute of Experimental Botany, Academy of Sciences of the Czech Republic, CZ-78371 Olomouc, Czech Republic (A.P., O.N.) nathalie.leduc@univ-angers.fr.
authors.forename: Nathalie
authors.identifier: 0000-0002-5323-0892
authors.initials: N
authors.lastname: Leduc
mesh_terms: D003583:Cytokinins / Q000378:metabolism* / Q000494:pharmacology; D003624:Darkness; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000528:radiation effects*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects*; D008027:Light; D018519:Meristem / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D008954:Models, Biological; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D027826:Rosa / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D013997:Time Factors; D052584:Xylem / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D003583:Cytokinins; D010937:Plant Growth Regulators; D010940:Plant Proteins