caa a22 4500 477099912 CHVBK 20180405111537.0 cr unu---uuuuu 170330e19960901xx s 000 0 eng 10.1007/BF00196649 doi (NATIONALLICENCE)springer-10.1007/BF00196649 Effect of ammonium on the regulation of nitrate and nitrite transport systems in roots of intact barley ( Hordeum vulgare L.) seedlings [Elektronische Daten] [Muhammad Aslam, Robert Travis, D. Rains, Ray Huffaker] The effect of NH 4 + on the regulation of NO 3 − and NO 2 − transport systems in roots of intact barley (Hordeum vulgareL.) seedlings grown in NO 3 − or NO 2 − was studied. Ammonium partially inhibited "induction” of both transport systems. The inhibition was less severe in NO 2 − -fed than in NO 3 − -fed seedlings, presumably due to lower uptake of NH 4 + in the presence of NO 2 − . In seedlings pretreated with NH 4 + subsequent "induction” was inhibited only when NH 4 + was also present during "induction”, even though pretreated roots accumulated high levels of NH 4 + . This indicates that inhibition may be regulated by NH 4 + concentration in the cytoplasm rather than its total accumulation in roots. L-Methionine sulfoximine did not relieve the inhibition by NH 4 + , suggesting that inhibition is caused by NH 4 + itself rather than by its assimilation product(s). Ammonium inhibited subsequent expression of NO 3 − transport activity similarly in roots grown in 0.1, 1.0, or 10 mM NO 3 − for 24 h (steady-state phase) or 4 d (decline phase), indicating that it has a direct, rather than general feedback effect. "Induction” of the NO 3 − transport system was about twice as sensitive to NH 4 + as compared to the NO 2 − transport system. This may relate to higher turnover rates of membraneassociated NO 3 − -transport proteins. Springer-Verlag, 1996 Ammonium nationallicence Hordeum nationallicence Induction (ion uptake) nationallicence Nitrate, nitrite uptake nationallicence Mes : 2(N-morpholino)ethanesulfonic acid nationallicence MSO : L-methionine sulfoximine nationallicence Aslam Muhammad Department of Agronomy and Range Science, University of California, 95616, Davis, CA, USA aut Travis Robert Department of Agronomy and Range Science, University of California, 95616, Davis, CA, USA aut Rains D. Department of Agronomy and Range Science, University of California, 95616, Davis, CA, USA aut Huffaker Ray Department of Agronomy and Range Science, University of California, 95616, Davis, CA, USA aut Planta Springer-Verlag 200/1(1996-09-01), 58-63 0032-0935 200:1<58 1996 200 425 https://doi.org/10.1007/BF00196649 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00196649 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Aslam Muhammad Department of Agronomy and Range Science, University of California, 95616, Davis, CA, USA aut NATIONALLICENCE 700 1- Travis Robert Department of Agronomy and Range Science, University of California, 95616, Davis, CA, USA aut NATIONALLICENCE 700 1- Rains D. Department of Agronomy and Range Science, University of California, 95616, Davis, CA, USA aut NATIONALLICENCE 700 1- Huffaker Ray Department of Agronomy and Range Science, University of California, 95616, Davis, CA, USA aut NATIONALLICENCE 773 0- Planta Springer-Verlag 200/1(1996-09-01), 58-63 0032-0935 200:1<58 1996 200 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer