title: Cytokinin activity of disubstituted aminopurines in Amaranthus.
abstract: Cytokinin (CK) receptors have different affinities for certain ligands, and consequently, studies of the plant's response to CK analogues constitute a good approach to identify active compounds that trigger specific plant responses. In this study, N(6) and N(6),N(6)-substituted CK analogues were synthesized and their CK-like activity was examined in the Amaranthus betacyanin and the bacterial receptor assay. The compounds showed CK-like activities that were not always associated with their binding affinity to the Arabidopsis receptors AHK3 and CRE1/AHK4. The highest level of activity in both bioassays was obtained for the N(6)-alkylaminopurines, which showed an especially high binding affinity to AHK3. In contrast to previously published data, we found remarkable activity of N(6),N(6)-alkylbenzylaminopurines in the Amaranthus betacyanin bioassay, which was not associated with their binding affinity to the tested receptors. The N(6),N(6)-substituted CK that showed the highest activity at the lowest concentration, N(6),N(6)-methylbenzylaminopurine (BAP-C1), was studied to determine its effect on different leaf parameters of whole Amaranthus plants, with benzylaminopurine (BAP) used as standard compound. The interaction with ethylene was examined in plants supplied with the ethylene-synthesis inhibitor aminooxiacetic acid (AOA). After 3d, the CKs supplied in the solution culture exerted effects on leaf dry weight and gas-exchange parameters. These effects of exogenous CKs are suggested to be ethylene-synthesis dependent.
authors.affiliation: Grup de Química Bioinorgànica i Bioorgànica, Departament de Química, Universitat de les Illes Balears, Ctra. Valldemossa km 7.5, 07122 Palma de Mallorca, Spain.
authors.forename: Angel
authors.initials: A
authors.lastname: García-Raso
authors.forename: Catalina
authors.initials: C
authors.lastname: Cabot
authors.forename: Juan Jesús
authors.initials: JJ
authors.lastname: Fiol
authors.forename: Lukás
authors.initials: L
authors.lastname: Spíchal
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Nisler
authors.forename: Andrés
authors.initials: A
authors.lastname: Tasada
authors.forename: Joana Maria
authors.initials: JM
authors.lastname: Luna
authors.forename: Francisca M
authors.initials: FM
authors.lastname: Albertí
authors.forename: John V
authors.initials: JV
authors.lastname: Sibole
mesh_terms: D015075:2-Aminopurine / Q000378:metabolism*; D027721:Amaranthus / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001593:Benzyl Compounds / Q000378:metabolism; D002232:Carbocyanines / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism*; D000071677:Histidine Kinase; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism; D011687:Purines / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D001593:Benzyl Compounds; D002232:Carbocyanines; D003583:Cytokinins; D011687:Purines; D011956:Receptors, Cell Surface; D015075:2-Aminopurine; D011494:Protein Kinases; D000071677:Histidine Kinase; C000605493:AHK3 protein, Arabidopsis; C421783:WOL protein, Arabidopsis; C480551:benzylaminopurine