RESUMEN
Identification of cytokinins in differentiated leaf cells has received little attention. We have carried out immunohistochemical localization of cytokinins in leaves of transgenic tobacco plants in which the level of increased due to induced in their roots the expression of ipt-gene controlling cytokinin synthesis. Immuno-labeling of cytokinins with the help of antibodies raised against zeatin riboside was characteristic of mesophyll cells. The label was localized in cytoplasm adjacent to cell walls and was absent in vacuoles. Immunohistochemical staining also revealed the presence of cytokinins in guard cells. Induction of cytokinin synthesis enhanced the immunohistochemical staining of both mesophyll cells and guard cells, which was accompanied by elevated stomatal conductance. The possibility of a direct effect of cytokinins on stomatal conductance and their indirect influence through photosynthesis in the mesophyll cells is discussed.
Asunto(s)
Transferasas Alquil y Aril/genética , Citocininas/biosíntesis , Células del Mesófilo/metabolismo , Nicotiana/metabolismo , Estomas de Plantas/metabolismo , Plantas Modificadas Genéticamente/metabolismo , Transferasas Alquil y Aril/metabolismo , Anticuerpos/química , Pared Celular/química , Pared Celular/metabolismo , Citocininas/análisis , Conductividad Eléctrica , Regulación de la Expresión Génica de las Plantas , Inmunohistoquímica , Isopenteniladenosina/análogos & derivados , Isopenteniladenosina/análisis , Isopenteniladenosina/química , Células del Mesófilo/química , Fotosíntesis/genética , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Estomas de Plantas/química , Nicotiana/genéticaRESUMEN
Immunohystochemical localization of cytokinins in cells of different root zones of wheat plants showed intensive immunostaining of zeatin in the apical root zone and its subsequent decline with the increase in the distance from the root tip. More intensive labeling of metaxylem and parenchyma cells of the root central cylinder was observed on the sections of the zone where root hairs appeared. Above this zone the decline in immunostaining of the cells of the central cylinder was paralleled by the signs if finalization of differentiation of the xylem vessels shown by lignin deposition. The data of immunohystochemical staining were confirmed by the results of enzyme immunoassay of different cytokinin forms. Likely sources of zeatin accumulation are considered. Possibility of additional (alongside with that in apical root zone) synthesis of cytokinins in the vascular tissues of root and the role of cytokinins in stimulation oflignification are discussed.