Abstract
Changes in leaf water content, night-time accumulation of malic (δ-malate) and citric acid (δ-citrate) and phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) activity were followed for 60 d after germination in well watered and salt-stressed plants of the facultatively halophytic ephemeral Mesembryanthemum crystallinum L. To separate the effects of development, salt stress and water deficit on crassulacean acid metabolism (CAM) induction plants were stressed initially 10 d after germination and then successively at 1-wk intervals (five sets). Related to dry mass or organic matter (i.e. dry mass corrected for the mass of inorganic ions) water content started to decrease during the late embryonal phase of the life cycle. Water content on a dry mass basis was always lower in salt-stressed than in well watered individuals. However, on an organic matter basis no difference was detectable. This indicated that salt treatment did not reduce leaf water content but falsified the basis (dry mass). Increases in leaf succulence and in pressure potential prevented long-term water deficit in well watered and in salt-stressed plants. Instead, these changes displayed enhanced vacuolisation, which is an essential prerequisite for the development of CAM. The end of that differentiation process might allow the initiation of nocturnal malic acid accumulation in a threshold response. At the onset of each salt treatment, short-term water deficits occurred due to an incomplete osmotic adaptation independent of plant age. As δ-malate only appeared when plants were c. 35 d old this water deficit was unlikely to be a decisive CAM-inducing factor. About 2 wk after germination water content began to decline during the light periods in plants of all treatments. This pattern disappeared again when CAM had been fully established. Daytime transpirational water loss is therefore unlikely to be the decisive factor because it failed to induce the metabolic shift in young plants. Environmental stress (e.g. salt or drought) can therefore only induce δ-malate when leaf and plant differentiation has reached a certain stage.
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Claims 15
Claim · model-written summary
Leaf water content relative to dry mass or organic matter began to decline during the late embryonal phase.
- Taxon
- Mesembryanthemum crystallinum L.
Mesembryanthemum crystallinume0 - Organ / stage
- late embryonal phasee1
- Outcome
- water contente1
- Direction
- decreasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“Related to dry mass or organic matter (i.e. dry mass corrected for the mass of inorganic ions) water content started to decrease during the late embryonal phase of the life cycle.”
Claim · model-written summary
Salt-stressed plants had lower dry-mass-basis water content than well-watered plants.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Treatment
- salt-stressede1
- Outcome
- Water content on a dry mass basise1
- Direction
- lowere1
- Comparator
- well watered individualse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“Water content on a dry mass basis was always lower in salt-stressed than in well watered individuals.”
Claim · model-written summary
Salt-stressed and well-watered plants did not differ in water content on an organic-matter basis.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Treatment
- salt-stressede2
- Outcome
- organic matter basise1
- Direction
- no difference was detectablee1
- Comparator
- well watered individualse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“However, on an organic matter basis no difference was detectable.”
e2“salt-stressed than in well watered individuals”
Claim · model-written summary
Salt treatment did not reduce leaf water content; the dry-mass basis distorted the comparison.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Treatment
- salt treatmente1
- Outcome
- leaf water contente1
- Direction
- did not reducee1
- Qualifier
- falsified the basis (dry mass)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“This indicated that salt treatment did not reduce leaf water content but falsified the basis (dry mass).”
Claim · model-written summary
Increased leaf succulence and pressure potential prevented long-term water deficit.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Outcome
- long-term water deficite1
- Direction
- preventede1
- Qualifier
- Increases in leaf succulence and in pressure potentiale1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“Increases in leaf succulence and in pressure potential prevented long-term water deficit in well watered and in salt-stressed plants.”
Claim · model-written summary
The succulence and pressure-potential changes indicated enhanced vacuolisation, described as a prerequisite for CAM development.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Outcome
- development of CAMe1
- Qualifier
- enhanced vacuolisatione1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“Instead, these changes displayed enhanced vacuolisation, which is an essential prerequisite for the development of CAM.”
Claim · model-written summary
Completion of differentiation might permit nocturnal malic acid accumulation in a threshold response.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Outcome
- nocturnal malic acid accumulatione1
- Qualifier
- end of that differentiation processe1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“The end of that differentiation process might allow the initiation of nocturnal malic acid accumulation in a threshold response.”
Claim · model-written summary
Each salt treatment produced short-term water deficits at onset, independent of plant age.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Treatment
- salt treatmente1
- Outcome
- short-term water deficitse1
- Qualifier
- independent of plant agee1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“At the onset of each salt treatment, short-term water deficits occurred due to an incomplete osmotic adaptation independent of plant age.”
Claim · model-written summary
Incomplete osmotic adaptation explained short-term deficits after salt treatment.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Treatment
- salt treatmente1
- Outcome
- short-term water deficitse1
- Qualifier
- incomplete osmotic adaptatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“At the onset of each salt treatment, short-term water deficits occurred due to an incomplete osmotic adaptation independent of plant age.”
Claim · model-written summary
δ-malate appeared only when plants were about 35 days old.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Outcome
- δ-malatee1
- Value
- c. 35 de1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“As δ-malate only appeared when plants were c. 35 d old”
Claim · model-written summary
Short-term water deficit was considered unlikely to be the decisive CAM-inducing factor.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Outcome
- CAM-inducing factore1
- Qualifier
- this water deficite1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“this water deficit was unlikely to be a decisive CAM-inducing factor.”
Claim · model-written summary
Water content began to decline during light periods about two weeks after germination in all treatments.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Outcome
- water contente1
- Direction
- declinee1
- Value
- 2 wke1
- Qualifier
- during the light periodse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“About 2 wk after germination water content began to decline during the light periods in plants of all treatments.”
Claim · model-written summary
The daytime water-content decline disappeared after CAM was fully established.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Outcome
- This pattern disappearede1
- Qualifier
- when CAM had been fully establishede1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“This pattern disappeared again when CAM had been fully established.”
Claim · model-written summary
Daytime transpirational water loss was considered unlikely to cause the metabolic shift because it did not induce the shift in young plants.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Outcome
- metabolic shifte1
- Qualifier
- Daytime transpirational water losse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“Daytime transpirational water loss is therefore unlikely to be the decisive factor because it failed to induce the metabolic shift in young plants.”
Claim · model-written summary
Environmental stress can induce δ-malate only after sufficient leaf and plant differentiation.
- Taxon
- Mesembryanthemum crystallinum L.Mesembryanthemum crystallinume0
- Treatment
- Environmental stress (e.g. salt or drought)e1
- Outcome
- δ-malatee1
- Qualifier
- leaf and plant differentiation has reached a certain stagee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mesembryanthemum crystallinum L.”
e1“Environmental stress (e.g. salt or drought) can therefore only induce δ-malate when leaf and plant differentiation has reached a certain stage.”
The same questions in other papers
salinity · growth · Mesembryanthemum crystallinum (common iceplant)Results agree
2 papers in the same direction as this paper
- negative
- no effect
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.