title: Immunocytochemical location of endogenous cytokinins in buds of kiwifruit (Actinidia deliciosa) during the first hours of in vitro culture.
abstract: Post-embedding immunocytochemical techniques using peroxidase-antiperoxidase as markers for light microscopy or immunoglobulin G-gold for electron microscopy respectively were used for the localization of cytokinins [9-beta-D-ribofuranosil-N6-(delta2-isopentenil) adenina ([9R]iP), 9-beta-D-ribofuranosyl-zeatin ([9R]Z) and 9-beta-D-ribofuranosyl-dihydrozeatin ([9R](diH)Z)] in kiwifruit (Actinidia deliciosa) meristematic cells of the second nodal segment. Immunolocation at the cellular level was carried out in cells from explants grown during 16 and 72 h in liquid medium. Subcellular immunolocalization was performed in cells from explants grown for 35 d on agar solidified-medium and for 30 min, 4 and 16 h in liquid medium with cellulose plugs as explant support. Taken as a whole, the results obtained for Actinidia deliciosa show that the studied cytokinins change their location during the culture period, although they can always be found to a greater or lesser extent in the nucleus and the cytoplasm. For instance, [9R]Z appears in the cytoplasm and in the nucleus during the first hours of culture and later is the only one that appears located mainly in nucleus. On the other hand, [9R](diH)Z changes from being predominantly located in the nucleus to practically appearing only in the cytoplasm at the end of the culture period. [9R]iP is principally found up to 4 h of culture in the cytoplasm, and at 16 h is evenly distributed in all the subcellular compartments except in the chloroplast. The existence of a large amount of cytokinins in the nucleus during the first hours of culture compared with the immunolabelling density at 35 d is probably due to the activation of cell cycle mechanisms leading to organogenic development at the beginning of culture.
authors.affiliation: Departamento de Biología de Organismos y Sistemas, C/Catedrático Rodrigo Uría, Oviedo, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Moncaleán
authors.forename: C
authors.initials: C
authors.lastname: López-Iglesias
authors.forename: B
authors.initials: B
authors.lastname: Fernández
authors.forename: A
authors.initials: A
authors.lastname: Rodríguez
mesh_terms: D029042:Actinidia; D002467:Cell Nucleus / Q000737:chemistry; D002478:Cells, Cultured; D003583:Cytokinins / Q000032:analysis*; D003593:Cytoplasm / Q000737:chemistry; D007124:Immunoenzyme Techniques; D018519:Meristem / Q000737:chemistry; D018514:Plant Structures / Q000737:chemistry*; D010944:Plants
chemical_list: D003583:Cytokinins