Abstract
Changes in root hydraulic resistance in response to alterations in nitrate supply were explored in detail as a potential mechanism that allows plants to respond rapidly to changes in their environment. Sunflower (Helianthus annuus cv. Holiday) plants grown hydroponically with limited nitrate availability (200 micromol l(-1)) served as our model system. Experimental plants were 6-9-weeks-old with total dry mass of 2-4 g. Root pressurization of intact plants and detached root systems was used to elucidate the temporal dynamics of root hydraulic properties in sunflower plants following changes in external nitrate availability. The response was rapid, with a 20% decrease in hydraulic resistance occurring within the first hour after the addition of 5 mM nitrate and the magnitude of the effect was dependent on nitrate concentration. The change in root hydraulic resistance was largely reversible, although the temporal dynamics of the response to nitrate addition versus nitrate withdrawal was not symmetric (a gradual decrease in resistance versus its fast increase), raising the possibility that the underlying mechanisms may also differ. Evidence is presented that the observed changes in root hydraulic properties require the assimilation of nitrate by root cells. The hydraulic resistance of roots, previously stimulated by the addition of nitrate, increased more than in control plants in low nitrate under anoxia and that suggests a key role of aquaporin activity in this response. It is proposed that a rapid decrease in root hydraulic resistance in the presence of increased nitrate availability is an important trait that could enhance a plant's ability to compete for nitrate in the soil.
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Claims 7
Claim · model-written summary
Adding 5 mM nitrate decreased root hydraulic resistance by 20% within the first hour.
- Taxon
- Helianthus annuus
Helianthus annuuse0 - Treatment
- addition of 5 mM nitratee1
- Outcome
- hydraulic resistancee1
- Direction
- decreasee1
- Value
- 20%e1
- Qualifier
- within the first houre1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sunflower (Helianthus annuus cv. Holiday) plants grown hydroponically with limited nitrate availability”
e1“The response was rapid, with a 20% decrease in hydraulic resistance occurring within the first hour after the addition of 5 mM nitrate and the magnitude of the effect was dependent on nitrate concentration”
Claim · model-written summary
The magnitude of the nitrate effect on root hydraulic resistance depended on nitrate concentration.
- Taxon
- Helianthus annuusHelianthus annuuse0
- Treatment
- nitrate concentratione1
- Outcome
- magnitude of the effecte1
- Direction
- dependente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sunflower (Helianthus annuus cv. Holiday) plants grown hydroponically with limited nitrate availability”
e1“The response was rapid, with a 20% decrease in hydraulic resistance occurring within the first hour after the addition of 5 mM nitrate and the magnitude of the effect was dependent on nitrate concentration”
Claim · model-written summary
The change in root hydraulic resistance was largely reversible.
- Taxon
- Helianthus annuusHelianthus annuuse0
- Outcome
- change in root hydraulic resistancee2
- Qualifier
- largely reversiblee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sunflower (Helianthus annuus cv. Holiday) plants grown hydroponically with limited nitrate availability”
e2“The change in root hydraulic resistance was largely reversible”
Claim · model-written summary
The temporal dynamics of the response to nitrate addition and to nitrate withdrawal were not symmetric.
- Taxon
- Helianthus annuusHelianthus annuuse0
- Treatment
- nitrate addition versus nitrate withdrawale3
- Outcome
- temporal dynamics of the responsee3
- Direction
- not symmetrice3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sunflower (Helianthus annuus cv. Holiday) plants grown hydroponically with limited nitrate availability”
e3“the temporal dynamics of the response to nitrate addition versus nitrate withdrawal was not symmetric”
Claim · model-written summary
Changes in root hydraulic properties require assimilation of nitrate by root cells.
- Taxon
- Helianthus annuusHelianthus annuuse0
- Compound
- nitratee4
- Outcome
- changes in root hydraulic propertiese4
- Qualifier
- assimilation of nitrate by root cellse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sunflower (Helianthus annuus cv. Holiday) plants grown hydroponically with limited nitrate availability”
e4“Evidence is presented that the observed changes in root hydraulic properties require the assimilation of nitrate by root cells”
Claim · model-written summary
Under anoxia, root hydraulic resistance of nitrate-stimulated plants increased more than in control plants in low nitrate.
- Taxon
- Helianthus annuusHelianthus annuuse0
- Treatment
- anoxiae5
- Outcome
- hydraulic resistancee5
- Direction
- increased moree5
- Comparator
- control plantse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sunflower (Helianthus annuus cv. Holiday) plants grown hydroponically with limited nitrate availability”
e5“The hydraulic resistance of roots, previously stimulated by the addition of nitrate, increased more than in control plants in low nitrate under anoxia and that suggests a key role of aquaporin activity in this response”
Claim · model-written summary
Aquaporin activity is suggested to play a key role in the root hydraulic response to nitrate.
- Taxon
- Helianthus annuusHelianthus annuuse0
- Outcome
- hydraulic resistancee5
- Qualifier
- a key role of aquaporin activitye5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sunflower (Helianthus annuus cv. Holiday) plants grown hydroponically with limited nitrate availability”
e5“The hydraulic resistance of roots, previously stimulated by the addition of nitrate, increased more than in control plants in low nitrate under anoxia and that suggests a key role of aquaporin activity in this response”
The same questions in other papers
nitrogen · disease · Helianthus annuus (common sunflower)Positive and negative results
2 papers in the same direction as this paper · 2 in the opposite direction
- negative
- negative
- positive
1 paper more in this group
See all 5 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.