Abstract
The NAR2 protein of Chlamydomonas reinhardtii has no known transport activity yet it is required for high-affinity nitrate uptake. Arabidopsis (Arabidopsis thaliana) possesses two genes, AtNRT3.1 and AtNRT3.2, that are similar to the C. reinhardtii NAR2 gene. AtNRT3.1 accounts for greater than 99% of NRT3 mRNA and is induced 6-fold by nitrate. AtNRT3.2 was expressed constitutively at a very low level and did not compensate for the loss of AtNRT3.1 in two Atnrt3.1 mutants. Nitrate uptake by roots and nitrate induction of gene expression were analyzed in two T-DNA mutants, Atnrt3.1-1 and Atnrt3.1-2, disrupted in the AtNRT3.1 promoter and coding regions, respectively, in 5-week-old plants. Nitrate induction of the nitrate transporter genes AtNRT1.1 and AtNRT2.1 was reduced in Atnrt3.1 mutant plants, and this reduced expression was correlated with reduced nitrate concentrations in the tissues. Constitutive high-affinity influx was reduced by 34% and 89%, respectively, in Atnrt3.1-1 and Atnrt3.1-2 mutant plants, while high-affinity nitrate-inducible influx was reduced by 92% and 96%, respectively, following induction with 1 mm KNO(3) after 7 d of nitrogen deprivation. By contrast, low-affinity influx appeared to be unaffected. Thus, the constitutive high-affinity influx and nitrate-inducible high-affinity influx (but not the low-affinity influx) of higher plant roots require a functional AtNRT3 (NAR2) gene.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 11
Claim · model-written summary
AtNRT3.1 accounted for more than 99% of NRT3 mRNA.
- Taxon
- Arabidopsis
Arabidopsist0 - Gene
- AtNRT3.1e0
- Outcome
- NRT3 mRNAe0
- Value
- greater than 99%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AtNRT3.1 accounts for greater than 99% of NRT3 mRNA”
t0“Arabidopsis”
Claim · model-written summary
Nitrate induced AtNRT3.1 expression sixfold.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- nitratee0
- Gene
- AtNRT3.1e0
- Outcome
- NRT3 mRNAe0
- Direction
- inducede0
- Value
- 6-folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AtNRT3.1 accounts for greater than 99% of NRT3 mRNA and is induced 6-fold by nitrate.”
t0“Arabidopsis”
Claim · model-written summary
AtNRT3.2 expression was constitutively very low.
- Taxon
- ArabidopsisArabidopsist0
- Gene
- AtNRT3.2e0
- Outcome
- expressed constitutively at a very low levele0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AtNRT3.2 was expressed constitutively at a very low level”
t0“Arabidopsis”
Claim · model-written summary
AtNRT3.2 did not compensate for AtNRT3.1 loss in two mutants.
- Taxon
- ArabidopsisArabidopsist0
- Material
- Atnrt3.1 mutantse0
- Gene
- AtNRT3.2e0
- Outcome
- did not compensate for the loss of AtNRT3.1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AtNRT3.2 was expressed constitutively at a very low level and did not compensate for the loss of AtNRT3.1 in two Atnrt3.1 mutants.”
t0“Arabidopsis”
Claim · model-written summary
Nitrate induction of AtNRT1.1 and AtNRT2.1 was reduced in Atnrt3.1 mutants.
- Taxon
- ArabidopsisArabidopsist0
- Material
- Atnrt3.1 mutant plantse0
- Treatment
- Nitratee0
- Gene
- AtNRT1.1 and AtNRT2.1e0
- Outcome
- induction of the nitrate transporter genese0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrate induction of the nitrate transporter genes AtNRT1.1 and AtNRT2.1 was reduced in Atnrt3.1 mutant plants”
t0“Arabidopsis”
Claim · model-written summary
Reduced transporter gene expression correlated with reduced tissue nitrate concentration.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- nitrate concentrations in the tissuese0
- Direction
- reducede0
- Qualifier
- reduced expressione0
Not reportedGene
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this reduced expression was correlated with reduced nitrate concentrations in the tissues”
t0“Arabidopsis”
Claim · model-written summary
Constitutive high-affinity influx was reduced by 34% in Atnrt3.1-1.
- Taxon
- ArabidopsisArabidopsist0
- Material
- Atnrt3.1-1e0
- Treatment
- Atnrt3.1-1e0
- Outcome
- Constitutive high-affinity influxe0
- Direction
- reducede0
- Value
- 34%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Constitutive high-affinity influx was reduced by 34% and 89%, respectively, in Atnrt3.1-1 and Atnrt3.1-2 mutant plants”
t0“Arabidopsis”
Claim · model-written summary
Constitutive high-affinity influx was reduced by 89% in Atnrt3.1-2.
- Taxon
- ArabidopsisArabidopsist0
- Material
- Atnrt3.1-2e0
- Treatment
- Atnrt3.1-2e0
- Outcome
- Constitutive high-affinity influxe0
- Direction
- reducede0
- Value
- 89%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Constitutive high-affinity influx was reduced by 34% and 89%, respectively, in Atnrt3.1-1 and Atnrt3.1-2 mutant plants”
t0“Arabidopsis”
Claim · model-written summary
Inducible high-affinity influx was reduced by 92% in Atnrt3.1-1.
- Taxon
- ArabidopsisArabidopsist0
- Material
- Atnrt3.1-1e1
- Treatment
- 1 mm KNO(3)e0
- Outcome
- high-affinity nitrate-inducible influxe0
- Direction
- reducede0
- Value
- 92%e0
- Qualifier
- after 7 d of nitrogen deprivatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high-affinity nitrate-inducible influx was reduced by 92% and 96%, respectively, following induction with 1 mm KNO(3) after 7 d of nitrogen deprivation.”
e1“Atnrt3.1-1 and Atnrt3.1-2 mutant plants”
t0“Arabidopsis”
Claim · model-written summary
Inducible high-affinity influx was reduced by 96% in Atnrt3.1-2.
- Taxon
- ArabidopsisArabidopsist0
- Material
- Atnrt3.1-2e1
- Treatment
- 1 mm KNO(3)e0
- Outcome
- high-affinity nitrate-inducible influxe0
- Direction
- reducede0
- Value
- 96%e0
- Qualifier
- after 7 d of nitrogen deprivatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high-affinity nitrate-inducible influx was reduced by 92% and 96%, respectively, following induction with 1 mm KNO(3) after 7 d of nitrogen deprivation.”
e1“Atnrt3.1-1 and Atnrt3.1-2 mutant plants”
t0“Arabidopsis”
Claim · model-written summary
Low-affinity influx appeared unaffected by AtNRT3.1 mutation.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- Atnrt3.1 mutant plantse1
- Outcome
- low-affinity influxe0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“By contrast, low-affinity influx appeared to be unaffected.”
e1“Atnrt3.1 mutant plants”
t0“Arabidopsis”
The same questions in other papers
nitrogen · molecular: expression · ArabidopsisPositive and negative results
5 papers in the same direction as this paper · 12 in the opposite direction
- positive
- negative
- no effect
14 papers more in this group
See all 18 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.