Abstract
Metabolic processes related to ammonium release and assimilation were investigated in a salt-sensitive rice (Oryza sativa L.) cultivar Anapurna. Ammonium content of the 3rd leaves increased 3-4 times when seedlings were treated with 100 mM NaCl for 6 days under both growth chamber light condition and in darkness (nonphotorespiration). An in vitro experiment revealed strong inhibition of protein synthesis as an effect of NaCl on the incorporation of 14C-leucine into protein. Exposure to salt stress slightly increased leaf proteolytic activity. The increase of proteolytic activity and decrease of protein synthesis, which directly causes accumulation of free amino acids, might lower the need for ammonium incorporation to form amino acids and indirectly cause the excessive accumulation of ammonium. No significant changes in the assimilatory activities of glutamine synthetase (GS; EC 6.3.1.2) and ferredoxin-dependent glutamate synthase (Fd-GOGAT; EC 1.4.7.1) were found under salt stress. Salt treatment changed the balance of the direction of glutamate dehydrogenase (NAD(H); EC 1.4.1.2); the aminating (NADH-GDH) activity increased while deaminating (NAD-GDH) activity decreased. We conclude that the accumulation of ammonium under salt stress was not due to inhibition of assimilatory activity of GS/GOGAT cycle or aminating GDH. Since these enzymes require supply of C-skeleton in the form of 2-oxoglutarate, reductant and energy to function, the reduction of photosynthetic capacity and the decrease of 2-oxoglutarate might be responsible for the excess accumulation of ammonium in salt-stressed seedlings.
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Claims 11
Claim · model-written summary
Rice leaf ammonium content rose three to fourfold after 100 mM NaCl for six days in light and dark.
- Taxon
- rice
Oryza sativae1 - Organ / stage
- 3rd leavese0
- Treatment
- 100 mM NaCl for 6 dayse0
- Outcome
- Ammonium contente0
- Direction
- increasede0
- Value
- 3-4 timese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ammonium content of the 3rd leaves increased 3-4 times when seedlings were treated with 100 mM NaCl for 6 days under both growth chamber light condition and in darkness (nonphotorespiration)”
e1“rice (Oryza sativa L.)”
Claim · model-written summary
NaCl strongly inhibited protein synthesis in vitro.
- Taxon
- riceOryza sativae1
- Treatment
- NaCle0
- Outcome
- protein synthesise0
- Direction
- inhibitione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“strong inhibition of protein synthesis as an effect of NaCl on the incorporation of 14C-leucine into protein”
e1“rice (Oryza sativa L.)”
Claim · model-written summary
Salt stress slightly increased leaf proteolytic activity.
- Taxon
- riceOryza sativae1
- Treatment
- salt stresse0
- Outcome
- leaf proteolytic activitye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exposure to salt stress slightly increased leaf proteolytic activity”
e1“rice (Oryza sativa L.)”
Claim · model-written summary
GS assimilatory activity did not change significantly under salt stress.
- Taxon
- riceOryza sativae1
- Treatment
- salt stresse0
- Gene
- glutamine synthetasee0
- Outcome
- assimilatory activities of glutamine synthetasee0
- Direction
- No significant changese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No significant changes in the assimilatory activities of glutamine synthetase (GS; EC 6.3.1.2) and ferredoxin-dependent glutamate synthase (Fd-GOGAT; EC 1.4.7.1) were found under salt stress”
e1“rice (Oryza sativa L.)”
Claim · model-written summary
Fd-GOGAT assimilatory activity did not change significantly under salt stress.
- Taxon
- riceOryza sativae1
- Treatment
- salt stresse0
- Gene
- ferredoxin-dependent glutamate synthasee0
- Outcome
- assimilatory activities of glutamine synthetase (GS; EC 6.3.1.2) and ferredoxin-dependent glutamate synthasee0
- Direction
- No significant changese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“No significant changes in the assimilatory activities of glutamine synthetase (GS; EC 6.3.1.2) and ferredoxin-dependent glutamate synthase (Fd-GOGAT; EC 1.4.7.1) were found under salt stress”
e1“rice (Oryza sativa L.)”
Claim · model-written summary
Salt treatment increased aminating NADH-GDH activity.
- Taxon
- riceOryza sativae1
- Treatment
- Salt treatmente0
- Gene
- glutamate dehydrogenasee0
- Outcome
- aminating (NADH-GDH) activitye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Salt treatment changed the balance of the direction of glutamate dehydrogenase (NAD(H); EC 1.4.1.2); the aminating (NADH-GDH) activity increased”
e1“rice (Oryza sativa L.)”
Claim · model-written summary
Salt treatment decreased deaminating NAD-GDH activity.
- Taxon
- riceOryza sativae2
- Treatment
- Salt treatmente1
- Gene
- glutamate dehydrogenasee1
- Outcome
- deaminating (NAD-GDH) activitye0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“deaminating (NAD-GDH) activity decreased”
e1“Salt treatment changed the balance of the direction of glutamate dehydrogenase”
e2“rice (Oryza sativa L.)”
Claim · model-written summary
Authors suggest increased proteolysis and reduced protein synthesis lower ammonium incorporation demand and indirectly cause accumulation.
- Taxon
- riceOryza sativae1
- Outcome
- excessive accumulation of ammoniume0
- Qualifier
- increase of proteolytic activity and decrease of protein synthesise0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The increase of proteolytic activity and decrease of protein synthesis, which directly causes accumulation of free amino acids, might lower the need for ammonium incorporation to form amino acids and indirectly cause the excessive accumulation of ammonium”
e1“rice (Oryza sativa L.)”
Claim · model-written summary
Authors conclude ammonium accumulation was not due to inhibition of GS/GOGAT or aminating GDH.
- Taxon
- riceOryza sativae1
- Outcome
- accumulation of ammoniume0
- Qualifier
- not due to inhibition of assimilatory activity of GS/GOGAT cycle or aminating GDHe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the accumulation of ammonium under salt stress was not due to inhibition of assimilatory activity of GS/GOGAT cycle or aminating GDH”
e1“rice (Oryza sativa L.)”
Claim · model-written summary
Authors propose reduced photosynthetic capacity as a cause of excess ammonium.
- Taxon
- riceOryza sativae1
- Outcome
- excess accumulation of ammoniume0
- Qualifier
- reduction of photosynthetic capacitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the reduction of photosynthetic capacity and the decrease of 2-oxoglutarate might be responsible for the excess accumulation of ammonium”
e1“rice (Oryza sativa L.)”
Claim · model-written summary
Authors propose decreased 2-oxoglutarate as a cause of excess ammonium.
- Taxon
- riceOryza sativae1
- Compound
- 2-oxoglutaratee0
- Outcome
- excess accumulation of ammoniume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the reduction of photosynthetic capacity and the decrease of 2-oxoglutarate might be responsible for the excess accumulation of ammonium”
e1“rice (Oryza sativa L.)”
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