Glutamine synthetase and glutamate dehydrogenase contribute differentially to proline accumulation in leaves of wheat (Triticum aestivum) seedlings exposed to different salinity.

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Wang ZQ, Yuan YZ, Ou JQ, Lin QH, Zhang CF

Glutamine synthetase and glutamate dehydrogenase contribute differentially to proline accumulation in leaves of wheat (Triticum aestivum) seedlings exposed to different salinity.

J Plant Physiol. 2007 Jun;164(6):695-701. Epub 2006 Jun 14.

PubMed ID

16777263 [ View in PubMed

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Abstract

To investigate the roles of ammonium-assimilating enzymes in proline synthesis under salinity stress, the activities of glutamine synthetase (GS; EC 6.3.1.2) and NADH-dependent glutamate dehydrogenase (NADH-GDH; EC 1.4.1.2) were determined in leaves of wheat (Triticum aestivum) seedlings exposed to salt stress at 150 and 300 mM NaCl for 5d. At the lower salinity, only GS activity increased markedly. At 300 mM NaCl, however, NADH-GDH activity increased while GS activity decreased. A significant accumulation of proline was found only at high-salinity exposure while glutamate, a proline precursor, increased dramatically under both low and high salinity. These data suggests that GS-catalysis might be the main glutamate synthesis pathway under low salinity. At 300 mM NaCl, glutamate seems to be preferentially produced through the process catalyzed by NADH-GDH. The increase of ammonium in salinity-stressed wheat seedlings might have resulted from increased photorespiration, which is responsible for the higher NADH-GDH activity. The activity of Delta(1)-pyrroline-5-carboxylate reductase (P5CR; EC 1.5.1.2) was significantly enhanced at 300 mM NaCl but remained unchanged at 150 mM. Delta(1)-Pyrroline-5-carboxylate synthetase (P5CS) activity did not show a specific response, indicating that P5CR might be the limiting step in proline synthesis from glutamate at high salinity.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
NADH	Pyrroline-5-carboxylate reductase 1, mitochondrial	Protein	Humans	Unknown	Not Available	Details