Abstract
Excessive use of nitrogen (N) fertilizer has increased ammonium ( NH 4 + ) accumulation in many paddy soils to levels that reduce rice vegetative biomass and yield. Based on studies of NH 4 + toxicity in rice ( Oryza sativa , Nanjing 44) seedlings cultured in agar medium, we found that NH 4 + concentrations above 0.75 m M inhibited the growth of rice and caused NH 4 + accumulation in both shoots and roots. Use of excessive NH 4 + also induced rhizosphere acidification and inhibited the absorption of K, Ca, Mg, Fe and Zn in rice seedlings. Under excessive NH 4 + conditions, exogenous γ‐aminobutyric acid (GABA) treatment limited NH 4 + accumulation in rice seedlings, reduced NH 4 + toxicity symptoms and promoted plant growth. GABA addition also reduced rhizosphere acidification and alleviated the inhibition of Ca, Mg, Fe and Zn absorption caused by excessive NH 4 + . Furthermore, we found that the activity of glutamine synthetase/NADH‐glutamate synthase (GS; EC 6.3.1.2/NADH‐GOGAT; EC1.4.1.14) in root increased gradually as the NH 4 + concentration increased. However, when the concentration of NH 4 + is more than 3 m M , GABA treatment inhibited NH 4 + ‐induced increases in GS/NADH‐GOGAT activity. The inhibition of ammonium assimilation may restore the elongation of seminal rice roots repressed by high NH 4 + . These results suggest that mitigation of ammonium accumulation and assimilation is essential for GABA‐dependent alleviation of ammonium toxicity in rice seedlings.
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Claims 13
Claim · model-written summary
NH4+ concentrations above 0.75 mM inhibited rice growth
- Taxon
- Oryza sativa
Oryza sativat0 - Treatment
- NH 4 + concentrations above 0.75 m Me1
- Outcome
- growth of ricee1
- Direction
- inhibitede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e1“NH 4 + concentrations above 0.75 m M inhibited the growth of rice and caused NH 4 + accumulation in both shoots and roots”
Claim · model-written summary
NH4+ concentrations above 0.75 mM increased NH4+ accumulation in shoots and roots
- Taxon
- Oryza sativaOryza sativat0
- Organ / stage
- shoots and rootse1
- Treatment
- NH 4 + concentrations above 0.75 m Me1
- Outcome
- NH 4 + accumulatione1
- Direction
- increaseinferrede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e1“NH 4 + concentrations above 0.75 m M inhibited the growth of rice and caused NH 4 + accumulation in both shoots and roots”
Claim · model-written summary
Excessive NH4+ induced rhizosphere acidification in rice seedlings
- Taxon
- Oryza sativaOryza sativat0
- Treatment
- excessive NH 4 +e2
- Outcome
- rhizosphere acidificatione2
- Direction
- inducede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e2“Use of excessive NH 4 + also induced rhizosphere acidification and inhibited the absorption of K, Ca, Mg, Fe and Zn in rice seedlings”
Claim · model-written summary
Excessive NH4+ inhibited absorption of K, Ca and Mg in rice seedlings
- Taxon
- Oryza sativaOryza sativat0
- Treatment
- excessive NH 4 +e2
- Outcome
- absorption of K, Ca, Mge2
- Direction
- inhibitede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e2“Use of excessive NH 4 + also induced rhizosphere acidification and inhibited the absorption of K, Ca, Mg, Fe and Zn in rice seedlings”
Claim · model-written summary
Excessive NH4+ inhibited absorption of Fe and Zn in rice seedlings
- Taxon
- Oryza sativaOryza sativat0
- Treatment
- excessive NH 4 +e2
- Outcome
- Fe and Zne2
- Direction
- inhibitede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e2“Use of excessive NH 4 + also induced rhizosphere acidification and inhibited the absorption of K, Ca, Mg, Fe and Zn in rice seedlings”
Claim · model-written summary
GABA limited NH4+ accumulation in rice seedlings under excessive NH4+
- Taxon
- Oryza sativaOryza sativat0
- Treatment
- GABAe3
- Outcome
- NH 4 + accumulatione3
- Direction
- limitede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e3“(GABA) treatment limited NH 4 + accumulation in rice seedlings, reduced NH 4 + toxicity symptoms and promoted plant growth”
Claim · model-written summary
GABA reduced NH4+ toxicity symptoms in rice seedlings
- Taxon
- Oryza sativaOryza sativat0
- Treatment
- GABAe3
- Outcome
- NH 4 + toxicity symptomse3
- Direction
- reducede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e3“(GABA) treatment limited NH 4 + accumulation in rice seedlings, reduced NH 4 + toxicity symptoms and promoted plant growth”
Claim · model-written summary
GABA promoted growth of rice seedlings
- Taxon
- Oryza sativaOryza sativat0
- Treatment
- GABAe3
- Outcome
- plant growthe3
- Direction
- promotede3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e3“(GABA) treatment limited NH 4 + accumulation in rice seedlings, reduced NH 4 + toxicity symptoms and promoted plant growth”
Claim · model-written summary
GABA reduced rhizosphere acidification under excessive NH4+
- Taxon
- Oryza sativaOryza sativat0
- Treatment
- GABA additione5
- Outcome
- rhizosphere acidificatione5
- Direction
- reducede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e5“GABA addition also reduced rhizosphere acidification and alleviated the inhibition of Ca, Mg, Fe and Zn absorption caused by excessive NH 4 +”
Claim · model-written summary
GABA alleviated the inhibition of Ca, Mg, Fe and Zn absorption caused by excessive NH4+
- Taxon
- Oryza sativaOryza sativat0
- Treatment
- GABA additione5
- Outcome
- Ca, Mg, Fe and Zn absorptione5
- Direction
- alleviatede5
- Comparator
- excessive NH 4 +e5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e5“GABA addition also reduced rhizosphere acidification and alleviated the inhibition of Ca, Mg, Fe and Zn absorption caused by excessive NH 4 +”
Claim · model-written summary
Root glutamine synthetase/NADH-glutamate synthase activity increased as NH4+ concentration increased
- Taxon
- Oryza sativaOryza sativat0
- Organ / stage
- roote7
- Treatment
- NH 4 + concentratione7
- Gene
- glutamine synthetasee6
- Outcome
- activitye6
- Direction
- increasede7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e6“the activity of glutamine synthetase”
e7“in root increased gradually as the NH 4 + concentration increased”
Claim · model-written summary
GABA inhibited the NH4+-induced increase in GS/NADH-GOGAT activity when NH4+ exceeded 3 mM
- Taxon
- Oryza sativaOryza sativat0
- Treatment
- GABAe2
- Outcome
- activitye2
- Direction
- inhibitede2
- Qualifier
- when the concentration of NH 4 + is more than 3 m Me1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e1“when the concentration of NH 4 + is more than 3 m M”
e2“GABA treatment inhibited NH 4 + ‐induced increases in GS/NADH‐GOGAT activity”
Claim · model-written summary
Inhibiting ammonium assimilation may restore elongation of seminal rice roots repressed by high NH4+
- Taxon
- Oryza sativaOryza sativat0
- Outcome
- elongation of seminal rice rootse1
- Qualifier
- inhibition of ammonium assimilatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“rice (Oryza sativa)”
e1“The inhibition of ammonium assimilation may restore the elongation of seminal rice roots repressed by high NH 4 +”
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See all 9 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.