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Nitrogen uptake and metabolism in Populus × canescens as affected by salinity
Author(s) -
Dluzniewska P.,
Gessler A.,
Dietrich H.,
Schnitzler J.P.,
Teuber M.,
Rennenberg H.
Publication year - 2007
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2006.01908.x
Subject(s) - ammonium , proline , nitrogen assimilation , salinity , glutamate synthase , chemistry , nitrate , metabolism , metabolite , phosphoenolpyruvate carboxylase , nitrogen cycle , biochemistry , nitrogen , amino acid , botany , glutamine synthetase , biology , photosynthesis , glutamine , ecology , organic chemistry
Summary• External salinization can affect different steps of nitrogen (N) metabolism (ion uptake, N assimilation, and amino acid and protein synthesis) depending on the inorganic N source. • Here, we assessed the net uptake of N supplied as nitrate or ammonium and N assimilation (combining metabolite analyses with molecular biological approaches) in grey poplar ( Populus × canescens ) plants grown under saline (75 m m NaCl) and control conditions. • The specific (µmol N g −1 dry weight fine roots h −1 ) and total plant (µmol N per plant h −1 ) N net uptake rates, total plant N content, total plant biomass and total leaf protein concentration were reduced under saline conditions when plants were supplied with ammonium. In both nutritional groups, salt treatment caused pronounced accumulation of soluble N compounds in the leaves. The mRNAs of genes coding for enzymes catalyzing rate‐limiting steps of both proline synthesis and degradation (delta‐1‐pyrroline‐5‐carboxylate synthase and proline dehydrogenase) as well as for NADH‐dependent glutamate synthase were accumulated under saline conditions. • Whereas under control conditions the plant N status seemed to be superior when ammonium was supplied, the N balance of ammonium‐fed plants was more severely affected by salt stress than that of plants supplied with nitrate. Possible metabolic implications of stress‐related accumulation of particular amino acids are discussed.