Abstract
Ber (Ziziphus mauritiana Lamk.) is a major fruit tree crop of the north-west Indian arid zone. In a study of the physiological basis of drought tolerance in this species, two glasshouse experiments were conducted in which trees were droughted during single stresscycles. In the first experiment, during a 13 d drying cycle, pre-dawn leaf water (ψleaf) and osmotic (ψπ) potentials in droughted trees declined from −0.5 and −1.4 MPa to −1.7 and −2.2 MPa, respectively, for a decrease in relative water content (θ) of 14%. During drought stress, changes in sugar metabolism were associated with significant increases in concentrations of hexose sugars (3.8-fold), cyclitol (scylloinositol; 1.5-fold), and proline (35-fold; expressed per unit dry weight), suggesting that altered solute partitioning may be an important factor in drought tolerance of Ziziphus. On rewatering, pre-dawn ψleaf and θ recovered fully, but ψπ remained depressed by 0.4 MPa relative to control values, indicating that solute concentration per unit water content had changed during the drought cycle. Evidence for osmotic adjustment was provided from a second study during which a gradual drought was imposed. Pressure-volume analysis revealed a 0.7 MPa reduction in osmotic potential at full turgor, with ψleaf at turgor loss depressed by ∼ 1 MPa in drought-stressed leaves. Coupled with osmotic adjustment, during gradual drought, was a 65% increase in bulk tissue elastic modulus (wall rigidity) which resulted in turgor loss at the same θ in both stressed and unstressed leaves. The possible ecological significance of maintenance of turgor potential and cell volume at low water potentials for drought tolerance in Ziziphus is discussed.
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Claims 12
Claim · model-written summary
Hexose sugar concentrations increased 3.8-fold during drought stress in Ziziphus mauritiana.
- Taxon
- Ziziphus mauritiana
Ziziphus mauritianat0 - Treatment
- drought stresse1
- Outcome
- concentrations of hexose sugarse1
- Direction
- increasese1
- Value
- 3.8-folde1
- Qualifier
- expressed per unit dry weighte1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e1“During drought stress, changes in sugar metabolism were associated with significant increases in concentrations of hexose sugars (3.8-fold), cyclitol (scylloinositol; 1.5-fold), and proline (35-fold; expressed per unit dry weight)”
Claim · model-written summary
Cyclitol concentration increased 1.5-fold during drought stress in Ziziphus mauritiana.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Treatment
- drought stresse1
- Outcome
- cyclitole1
- Direction
- increasese1
- Value
- 1.5-folde1
- Qualifier
- expressed per unit dry weighte1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e1“During drought stress, changes in sugar metabolism were associated with significant increases in concentrations of hexose sugars (3.8-fold), cyclitol (scylloinositol; 1.5-fold), and proline (35-fold; expressed per unit dry weight)”
Claim · model-written summary
Proline concentration increased 35-fold during drought stress in Ziziphus mauritiana.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Treatment
- drought stresse1
- Outcome
- prolinee1
- Direction
- increasese1
- Value
- 35-folde1
- Qualifier
- expressed per unit dry weighte1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e1“During drought stress, changes in sugar metabolism were associated with significant increases in concentrations of hexose sugars (3.8-fold), cyclitol (scylloinositol; 1.5-fold), and proline (35-fold; expressed per unit dry weight)”
Claim · model-written summary
Pre-dawn leaf water potential declined to −1.7 MPa during the drying cycle.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Treatment
- drying cyclee3
- Outcome
- pre-dawn leaf water (ψleaf)e2
- Direction
- declinede2
- Value
- −1.7e2
- Qualifier
- from −0.5 and −1.4e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e2“pre-dawn leaf water (ψleaf) and osmotic (ψπ) potentials in droughted trees declined from −0.5 and −1.4 MPa to −1.7 and −2.2 MPa, respectively, for a decrease in relative water content (θ) of 14%”
e3“during a 13 d drying cycle”
Claim · model-written summary
Osmotic potential declined to −2.2 MPa during the drying cycle.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Treatment
- drying cyclee3
- Outcome
- osmotic (ψπ) potentialse2
- Direction
- declinede2
- Value
- −2.2e2
- Qualifier
- from −0.5 and −1.4e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e2“pre-dawn leaf water (ψleaf) and osmotic (ψπ) potentials in droughted trees declined from −0.5 and −1.4 MPa to −1.7 and −2.2 MPa, respectively, for a decrease in relative water content (θ) of 14%”
e3“during a 13 d drying cycle”
Claim · model-written summary
Relative water content decreased by 14% during the drying cycle.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Treatment
- drying cyclee3
- Outcome
- relative water content (θ)e2
- Direction
- decreasee2
- Value
- 14%e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e2“pre-dawn leaf water (ψleaf) and osmotic (ψπ) potentials in droughted trees declined from −0.5 and −1.4 MPa to −1.7 and −2.2 MPa, respectively, for a decrease in relative water content (θ) of 14%”
e3“during a 13 d drying cycle”
Claim · model-written summary
On rewatering, pre-dawn leaf water potential and relative water content recovered fully.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Outcome
- pre-dawn ψleaf and θe4
- Direction
- recovered fullye4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e4“On rewatering, pre-dawn ψleaf and θ recovered fully”
Claim · model-written summary
Osmotic potential remained depressed by 0.4 MPa relative to control after rewatering.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Treatment
- drought cyclee5
- Outcome
- ψπe5
- Direction
- depressede5
- Value
- 0.4 MPae5
- Comparator
- control valuese5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e5“but ψπ remained depressed by 0.4 MPa relative to control values, indicating that solute concentration per unit water content had changed during the drought cycle”
Claim · model-written summary
Pressure-volume analysis showed a 0.7 MPa reduction in osmotic potential at full turgor during gradual drought.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Treatment
- gradual droughte7
- Outcome
- osmotic potential at full turgore6
- Direction
- reductione6
- Value
- 0.7 MPae6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e6“Pressure-volume analysis revealed a 0.7 MPa reduction in osmotic potential at full turgor”
e7“during which a gradual drought was imposed”
Claim · model-written summary
Leaf water potential at turgor loss was depressed by about 1 MPa in drought-stressed leaves.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Treatment
- drought-stressede2
- Outcome
- ψleaf at turgor losse2
- Direction
- depressede2
- Value
- ∼ 1 MPae2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e2“with ψleaf at turgor loss depressed by ∼ 1 MPa in drought-stressed leaves”
Claim · model-written summary
Bulk tissue elastic modulus increased by 65% during gradual drought.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Treatment
- gradual droughte3
- Outcome
- bulk tissue elastic moduluse3
- Direction
- increasee3
- Value
- 65%e3
- Qualifier
- wall rigiditye3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e3“Coupled with osmotic adjustment, during gradual drought, was a 65% increase in bulk tissue elastic modulus (wall rigidity)”
Claim · model-written summary
Turgor loss occurred at the same relative water content in stressed and unstressed leaves.
- Taxon
- Ziziphus mauritianaZiziphus mauritianat0
- Outcome
- turgor loss at the same θe4
- Qualifier
- in both stressed and unstressed leavese4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana”
e4“which resulted in turgor loss at the same θ in both stressed and unstressed leaves”