title: Cytokinin-dependent improvement in transgenic P(SARK)::IPT tobacco under nitrogen deficiency.
abstract: Wild-type (WT) and transgenic tobacco plants overexpressing isopentenyltransferase (IPT), a gene coding the rate-limiting step in cytokinin (CKs) synthesis, were grown under limited nitrogen (N) conditions to evaluate the role of CKs in NUE (N-use efficiency) and in different parameters that determine the quality of tobacco leaves. The results indicate that WT tobacco plants submitted to N deficiency show a decline in the leaf/root ratio, associated with a decrease in the NUE and in tobacco-leaf quality, defined by an increase in the quantity of nicotine. On the contrary, the transgenic plants submitted to N deficiency maintained the leaf/root ratio, presenting a higher NUE and greater quality of tobacco leaves than the WT plants, as the latter showed reduced nicotine and an increase in reducing sugars under severe N-deficiency conditions. Therefore, the overexpression of CKs under N deficiency could be a useful tool to improve tobacco cultivation, given that it could reduce N-fertilizer application and thereby provide economic savings and environmental benefits, maintaining yield and improving tobacco leaf quality.
authors: Department of Plant Physiology, Faculty of Science, University of Granada , 18071 Granada, Spain. mmrubio@ugr.es
authors: María Del Mar
authors: Mdel M
authors: Rubio-Wilhelmi
authors: Eva
authors: E
authors: Sanchez-Rodriguez
authors: Miguel Angel
authors: MA
authors: Rosales
authors: Begoña
authors: B
authors: Blasco
authors: Juan Jose
authors: JJ
authors: Rios
authors: Luis
authors: L
authors: Romero
authors: Eduardo
authors: E
authors: Blumwald
authors: Juan Manuel
authors: JM
authors: Ruiz
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics*; D003583:Cytokinins / Q000502:physiology*; D015870:Gene Expression; D009538:Nicotine / Q000032:analysis; D009584:Nitrogen / Q000008:administration & dosage* / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development; D018517:Plant Roots / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000254:growth & development*; D014026:Nicotiana / Q000254:growth & development*
chemical_list: D003583:Cytokinins; D009538:Nicotine; D019883:Alkyl and Aryl Transferases; C024274:adenylate isopentenyltransferase; D009584:Nitrogen