caa a22 4500 477100279 CHVBK 20180405111539.0 cr unu---uuuuu 170330e19961201xx s 000 0 eng 10.1007/BF00231396 doi (NATIONALLICENCE)springer-10.1007/BF00231396 Effect of nitrate on water transfer across roots of nitrogen pre-starved maize seedlings [Elektronische Daten] [Jackson Hoarau, Laure Barthes, Agnès Bousser, Eliane Deléens, Jean-Louis Prioul] The addition of 10 mM KNO3 to the solution bathing the roots of young nitrogen-starved seedlings of Zea mays L. enhanced root water transfer within 15 h, compared with 10 mM KCl addition. The free exudation flux was 2.2-3.9 times higher in excised KNO3-treated roots than in KCl-treated ones. Cryo-osmometry data for xylem sap suggested that, compared with chloride, nitrate treatment increased the steady solute flux into the xylem, but did not modify the osmotic concentration of sap. Root growth was not significantly modified by nitrate within 15 h. Root hydraulic conductances were measured by using either hydrostatic-pressure or osmotic-gradient methods. During hydrostatic experiments, the conductance (kp), which is thought to refer mainly to the apoplasmic pathway, was 1.6 times larger in KNO3-than in KCl-treated plants. From experiments in which polyethylene glycol (PEG) 8000 was used as external osmolyte, osmotic conductances (ks) were found to be smaller by 5-20 times than kp for the two kinds of plants. The KCl-treated roots were characterized by a low ks which was the same for influx or efflux of water. By contrast, KNO3-treated roots exhibited two distinct conductances ks1 and ks2, indicating that influx of water was easier than efflux when the water flow was driven by the osmotic pressure gradient. Infiltration of roots with KNO3 solution supported the idea that nitrate might enhance the efficiency of the cell-to-cell pathway. The low ks value of KCl-treated roots and the existence of two contrasting ks values (ks1 and ks2) for KNO3-treated roots are discussed in terms of reversible closing of water channels. Springer-Verlag, 1996 Hydraulic conductance nationallicence Nitrate nationallicence Zea mays roots nationallicence BM : basic medium nationallicence Ce : external solute concentration nationallicence Cx : xylem solute concentration nationallicence kp : hydrostatic conductance measured under hydrostatic pressure P (kp1: measured with P applied on the root system nationallicence kp2: measured with P applied on the xylem sap) nationallicence ks : osmotic conductance (ks1: low osmotic conductance, ks2: high osmotic conductance) nationallicence Lp : hydraulic conductivity nationallicence P : hydrostatic pressure nationallicence PEG : polyethylene glycol nationallicence Ψe : water potential of root bathing medium nationallicence Q0 : free exudation rate nationallicence Hoarau Jackson Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut Barthes Laure Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut Bousser Agnès Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut Deléens Eliane Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut Prioul Jean-Louis Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut Planta Springer-Verlag 200/4(1996-12-01), 405-415 0032-0935 200:4<405 1996 200 425 https://doi.org/10.1007/BF00231396 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00231396 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hoarau Jackson Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut NATIONALLICENCE 700 1- Barthes Laure Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut NATIONALLICENCE 700 1- Bousser Agnès Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut NATIONALLICENCE 700 1- Deléens Eliane Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut NATIONALLICENCE 700 1- Prioul Jean-Louis Laboratoire Structure et Métabolisme des Plantes, Institut de Biotechnologie des Plantes, CNRS, URA 1128, Båt. 630, Université de Paris-Sud, F-91405, Orsay Cedex aut NATIONALLICENCE 773 0- Planta Springer-Verlag 200/4(1996-12-01), 405-415 0032-0935 200:4<405 1996 200 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer