Abstract
Urea is the most widespread nitrogen (N) fertilizer worldwide and is rapidly degraded in soil to ammonium by urease. Ammonium is either taken up by plant roots or is further processed to nitrate by soil microorganisms. However, urea can be taken up by roots and is further degraded to ammonium by plant urease for assimilation. When urea is supplied under sterile conditions, it acts as a poor N source for seedlings or adult Arabidopsis thaliana plants. Here, the gene expression of young seedlings exposed to urea and ammonium nitrate nutrition was compared. Several primary metabolism and transport genes, including those for nitrate and urea, were differentially expressed in seedlings. However, urease and most major intrinsic proteins were not differentially expressed, with the exception of NIP6;1, a urea-permeable channel, which was repressed. Furthermore, little overlap with the gene expression with ammonium as the sole N source was observed, confirming that pure urea nutrition is not associated with the ammonium toxicity syndrome in seedlings. The direct root uptake of urea was increased under boron deficiency, in both the high and low affinity range. This activity was entirely mediated by the NIP5;1 channel, which was confirmed to transport urea when expressed in oocytes. The uptake of urea in the high and low affinity range was also determined for maize and wheat roots. The urea uptake by maize roots was only about half that of wheat, but was not stimulated by boron deficiency or N deficiency in either species. This analysis identifies novel components of the urea uptake systems in plants, which may become agronomically relevant to urea uptake and utilization, as stabilized urea fertilizers become increasingly popular.
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Claims 9
Claim · model-written summary
Several primary metabolism and transport genes, including those for nitrate and urea, were differentially expressed in Arabidopsis seedlings exposed to urea nutrition compared with ammonium nitrate.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae0 - Organ / stage
- seedlingse1
- Outcome
- differentially expressede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana”
e1“Several primary metabolism and transport genes, including those for nitrate and urea, were differentially expressed in seedlings”
Claim · model-written summary
NIP6;1, a urea-permeable channel, was repressed in Arabidopsis seedlings on urea nutrition, whereas urease and most other major intrinsic proteins were not differentially expressed.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Gene
- NIP6;1e1
- Outcome
- repressede1
- Direction
- repressede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana”
e1“urease and most major intrinsic proteins were not differentially expressed, with the exception of NIP6;1, a urea-permeable channel, which was repressed”
Claim · model-written summary
Gene expression under pure urea nutrition showed little overlap with that under ammonium as the sole N source in Arabidopsis seedlings.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Outcome
- overlap with the gene expression with ammonium as the sole N sourcee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana”
e1“little overlap with the gene expression with ammonium as the sole N source was observed”
Claim · model-written summary
Pure urea nutrition was not associated with the ammonium toxicity syndrome in seedlings.
- Taxon
- Arabidopsis thalianaArabidopsis thalianae0
- Organ / stage
- seedlingse1
- Treatment
- pure urea nutritione1
- Outcome
- ammonium toxicity syndromee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Arabidopsis thaliana”
e1“pure urea nutrition is not associated with the ammonium toxicity syndrome in seedlings”
Claim · model-written summary
Direct root uptake of urea was increased under boron deficiency in both the high and low affinity range.
- Treatment
- boron deficiencye0
- Outcome
- direct root uptake of ureae0
- Direction
- increasede0
- Qualifier
- in both the high and low affinity rangee0
Not reportedTaxonComparator
Verbatim
e0“The direct root uptake of urea was increased under boron deficiency, in both the high and low affinity range”
Claim · model-written summary
The boron-deficiency-stimulated urea uptake activity was entirely mediated by the NIP5;1 channel.
Not reportedTaxon
Verbatim
e0“This activity was entirely mediated by the NIP5;1 channel”
Claim · model-written summary
The NIP5;1 channel was confirmed to transport urea when expressed in oocytes.
Not reportedTaxon
Verbatim
e0“NIP5;1 channel, which was confirmed to transport urea when expressed in oocytes”
Claim · model-written summary
Urea uptake by maize roots was only about half that of wheat roots.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The urea uptake by maize roots was only about half that of wheat”
Claim · model-written summary
Urea uptake by maize and wheat roots was not stimulated by boron deficiency or N deficiency.
- Treatment
- boron deficiency or N deficiencye0
- Outcome
- urea uptakee0
- Direction
- not stimulatede0
- Qualifier
- in either speciese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The urea uptake by maize roots was only about half that of wheat, but was not stimulated by boron deficiency or N deficiency in either species”
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See all 489 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.