title: Nitrogen metabolism and gas exchange parameters associated with zinc stress in tobacco expressing an ipt gene for cytokinin synthesis.
abstract: Increased endogenous plant cytokinin (CK) content through transformation with an isopentyl transferase (ipt) gene has been associated with improved plant stress tolerance. The impact of zinc (tested levels Zn1=250, Zn2=500, Zn3=750mgkg(-1)soil) on gas exchange parameters (net photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration) and nitrogen utilization by plants resulted in changes of free amino acid concentrations (glutamic acid, glutamine, asparagine, aspartate, glycine, serine, cystein) and differed for transformed and non-transformed tobacco plants. For pot experiments, tobacco plants (Nicotiana tabacum L., cv. Wisconsin 38) transformed with a construct consisting of SAG12 promoter fused with the ipt gene for cytokinin synthesis (SAG plants) and its wild type (WT plants as a control) were used. Physiological analyses confirmed that SAG plants had improved zinc tolerance compared with the WT plants. The enhanced Zn tolerance of SAG plants was associated with the maintenance of accumulation of amino acids and with lower declines of photosynthetic and transpiration rates. In comparison to WT plants, SAG plants exposed to the highest Zn concentration accumulated lower concentrations of asparagine, which is a major metabolic product during senescence.
authors.affiliation: Department of Agro-Environmental Chemistry and Plant Nutrition, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 16521 Prague, Czech Republic. Electronic address: pavlikova@af.czu.cz.
authors.forename: Daniela
authors.initials: D
authors.lastname: Pavlíková
authors.affiliation: Isotope Laboratory, Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Vídeňská 1083, 14220 Prague, Czech Republic.
authors.forename: Milan
authors.initials: M
authors.lastname: Pavlík
authors.affiliation: Laboratory of Stress Physiology, Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, 16502 Prague, Czech Republic.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Procházková
authors.affiliation: Department of Agro-Environmental Chemistry and Plant Nutrition, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 16521 Prague, Czech Republic.
authors.forename: Veronika
authors.initials: V
authors.lastname: Zemanová
authors.affiliation: Department of Botany and Plant Physiology, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 16521 Prague, Czech Republic.
authors.forename: František
authors.initials: F
authors.lastname: Hnilička
authors.affiliation: Laboratory of Stress Physiology, Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, 16502 Prague, Czech Republic.
authors.forename: Naďa
authors.initials: N
authors.lastname: Wilhelmová
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D003583:Cytokinins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D009584:Nitrogen / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014026:Nicotiana / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D015032:Zinc / Q000633:toxicity*
chemical_list: D000596:Amino Acids; D003583:Cytokinins; D010940:Plant Proteins; D015032:Zinc; D009584:Nitrogen
keywords: Amino acid; Cytokinins; Photosynthetic rate; Senescence; Toxic element stress