Abstract
Lateral root initiation is strongly repressed in Arabidopsis by the combination of high external sucrose and low external nitrate. A previously isolated mutant, lin1, can overcome this repression. Here, we show that lin1 carries a missense mutation in the NRT2.1 gene. Several allelic mutants, including one in which the NRT2.1 gene is completely deleted, show similar phenotypes to lin1 and fail to complement lin1. NRT2.1 encodes a putative high-affinity nitrate transporter that functions at low external nitrate concentrations. Direct measurement of nitrate uptake and nitrate content in the lin1 mutant seedlings established that both are indeed reduced. Because repression of lateral root initiation in WT plants can be relieved by increased concentrations of external nitrate, it is surprising to find that repression is also relieved by a defect in a component of the high-affinity nitrate uptake system. Furthermore, lateral root initiation is increased in lin1 relative to WT even when seedlings are grown on nitrate-free media, suggesting that the mutant phenotype is nitrate-independent. These results indicate that NRT2.1 is a repressor of lateral root initiation and that this role is independent of nitrate uptake. We propose that Arabidopsis NRT2.1 acts either as a nitrate sensor or signal transducer to coordinate the development of the root system with nutritional cues.
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Claims 12
Claim · model-written summary
High external sucrose with low nitrate represses lateral root initiation in Arabidopsis.
- Taxon
- Arabidopsis
Arabidopsise0 - Treatment
- high external sucrose and low external nitratee0
- Outcome
- Lateral root initiatione0
- Direction
- repressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lateral root initiation is strongly repressed in Arabidopsis by the combination of high external sucrose and low external nitrate.”
Claim · model-written summary
The lin1 mutant overcomes repression of lateral root initiation.
- Taxon
- ArabidopsisArabidopsise1
- Material
- lin1e0
- Outcome
- lateral root initiationt0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A previously isolated mutant, lin1, can overcome this repression.”
t0“lateral root initiation”
t1“NRT2.1”
e1“in Arabidopsis”
Claim · model-written summary
lin1 carries a missense mutation in NRT2.1.
- Taxon
- ArabidopsisArabidopsise1
- Material
- lin1e0
- Gene
- NRT2.1e0
- Outcome
- missense mutatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lin1 carries a missense mutation in the NRT2.1 gene.”
e1“in Arabidopsis”
Claim · model-written summary
Several NRT2.1 allelic mutants share the lin1 phenotype and fail to complement lin1.
- Taxon
- ArabidopsisArabidopsise1
- Gene
- NRT2.1e0
- Outcome
- show similar phenotypes to lin1 and fail to complement lin1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Several allelic mutants, including one in which the NRT2.1 gene is completely deleted, show similar phenotypes to lin1 and fail to complement lin1.”
e1“in Arabidopsis”
Claim · model-written summary
NRT2.1 functions as a putative high-affinity nitrate transporter at low external nitrate.
- Taxon
- ArabidopsisArabidopsise1
- Gene
- NRT2.1e0
- Outcome
- putative high-affinity nitrate transportere0
- Qualifier
- low external nitrate concentrationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NRT2.1 encodes a putative high-affinity nitrate transporter that functions at low external nitrate concentrations.”
e1“in Arabidopsis”
Claim · model-written summary
Nitrate uptake is reduced in lin1 seedlings.
- Taxon
- ArabidopsisArabidopsise1
- Material
- lin1e0
- Outcome
- nitrate uptakee0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Direct measurement of nitrate uptake and nitrate content in the lin1 mutant seedlings established that both are indeed reduced.”
e1“in Arabidopsis”
Claim · model-written summary
Nitrate content is reduced in lin1 seedlings.
- Taxon
- ArabidopsisArabidopsise1
- Material
- lin1e0
- Outcome
- nitrate contente0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Direct measurement of nitrate uptake and nitrate content in the lin1 mutant seedlings established that both are indeed reduced.”
e1“in Arabidopsis”
Claim · model-written summary
Increased external nitrate relieves repression of lateral root initiation in WT plants.
- Taxon
- ArabidopsisArabidopsise1
- Material
- WTe0
- Treatment
- increased concentrations of external nitratee0
- Outcome
- repression of lateral root initiatione0
- Direction
- relievede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“repression of lateral root initiation in WT plants can be relieved by increased concentrations of external nitrate”
e1“in Arabidopsis”
Claim · model-written summary
The lin1 defect also relieves lateral root repression.
- Taxon
- ArabidopsisArabidopsise1
- Material
- lin1e2
- Outcome
- repressione0
- Direction
- relievede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“repression is also relieved by a defect in a component of the high-affinity nitrate uptake system”
e1“in Arabidopsis”
e2“A previously isolated mutant, lin1, can overcome this repression.”
Claim · model-written summary
lin1 has increased lateral root initiation relative to WT on nitrate-free medium.
- Taxon
- ArabidopsisArabidopsise1
- Material
- lin1e0
- Outcome
- lateral root initiatione0
- Direction
- increasede0
- Comparator
- WTe0
- Setting
- nitrate-free mediae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lateral root initiation is increased in lin1 relative to WT even when seedlings are grown on nitrate-free media”
e1“in Arabidopsis”
Claim · model-written summary
NRT2.1 represses lateral root initiation independently of nitrate uptake.
- Taxon
- ArabidopsisArabidopsise1
- Gene
- NRT2.1e0
- Outcome
- lateral root initiatione0
- Qualifier
- independent of nitrate uptakee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NRT2.1 is a repressor of lateral root initiation and that this role is independent of nitrate uptake”
e1“in Arabidopsis”
Claim · model-written summary
The authors propose that NRT2.1 acts as a nitrate sensor or signal transducer coordinating root development with nutrition.
- Taxon
- ArabidopsisArabidopsise0
- Gene
- NRT2.1e0
- Outcome
- development of the root systeme0
- Qualifier
- nitrate sensor or signal transducere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis NRT2.1 acts either as a nitrate sensor or signal transducer to coordinate the development of the root system with nutritional cues.”
The same questions in other papers
sucrose · growth · ArabidopsisPositive and negative results
7 papers in the same direction as this paper · 9 in the opposite direction
- positive
- positive
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See all 17 papers →nitrogen · growth · ArabidopsisPositive and negative results
12 papers in the same direction as this paper · 9 in the opposite direction
- positive
- negative
- positive
18 papers more in this group
See all 22 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.