Abstract
Effects of water stress and exogenous abscisic acid (ABA) treatments on thermotolerance of photosynthetic apparatus (PA) in cucumber (Cucumis sativus L.) leaves were investigated. Evaluation of thermotolerance was based on the heat sensitivity of photosystem II (PSII) based on chlorophyll fluorescence emission. Plants were water-stressed by either withholding water to intact plants or placing excised shoots in an open atmosphere in a glasshouse. The extent of water stress was monitored by measuring the water potential of leaves. At intervals during water stress treatment, the ratio of variable to maximum fluorescence (Fv/Fm) of leaves was determined. Immediately after that, the leaves were dipped in a water bath held at 45°C for 10 min and Fv/Fm values were determined again. Percentages of Fv/Fm values remaining after the heat treatment were used as a measure of thermotolerance of PA. With intact plants, thermotolerance of PA increased significantly when the leaf water potential was decreased to -1.0 MPa; it attained maximum at -1.5 to -2.0 MPa. However, the thermotolerance decreased when water potential was further lowered to -4.0 MPa. Leaves of excised shoots showed similar changes in thermotolerance of PA in response to the decrease in water potential, except that the maximum tolerance was obtained at -0.8 MPa. When intact plants were reirrigated after 3 days of water stress treatment, the thermotolerance of PA increased temporarily during the first 2 hr, and then decreased sharply within 24 hr to the level of the irrigated control plant leaves. Exogenous ABA applied to leaves of irrigated plants caused an increase in thermotolerance of PA depending on its concentrations. Leaves tre-ated with 1.00 mM ABA showed nearly complete tolerance of PA within a day; this high tolerance level was maintained for at least 6 days. Leaves treated with 0.01 to 0.25 mM ABA reached a peak tolerance after a day and then lost much of the ABA-induced thermotolerance after 3 days. The results indicate that the enhanced thermotolerance of PA in water-stressed cucumber leaves was probably mediated through a water-stress-induced increase in endogenous levels of ABA.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 12
Claim · model-written summary
Intact cucumber thermotolerance rose significantly as water potential fell to -1.0 MPa.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“thermotolerance of PA increased significantly when the leaf water potential was decreased to -1.0 MPa”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
Intact plant thermotolerance peaked at -1.5 to -2.0 MPa.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it attained maximum at -1.5 to -2.0 MPa”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
Thermotolerance declined when water potential fell to -4.0 MPa.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“thermotolerance decreased when water potential was further lowered to -4.0 MPa”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
Excised shoot leaves responded similarly, with maximum tolerance at -0.8 MPa.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaves of excised shoots showed similar changes in thermotolerance of PA in response to the decrease in water potential, except that the maximum tolerance was obtained at -0.8 MPa”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
Reirrigated plants showed a transient rise in thermotolerance in the first 2 hr.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“thermotolerance of PA increased temporarily during the first 2 hr”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
After reirrigation, thermotolerance declined within 24 hr to irrigated control level.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“then decreased sharply within 24 hr to the level of the irrigated control plant leaves”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
Exogenous ABA increased photosynthetic thermotolerance in a concentration dependent manner.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exogenous ABA applied to leaves of irrigated plants caused an increase in thermotolerance of PA depending on its concentrations”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
At 1.00 mM ABA, leaves reached nearly complete tolerance within a day.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaves tre-ated with 1.00 mM ABA showed nearly complete tolerance of PA within a day”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
At 1.00 mM ABA, high tolerance persisted at least six days.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this high tolerance level was maintained for at least 6 days”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
At 0.01 to 0.25 mM ABA, tolerance peaked after one day.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaves treated with 0.01 to 0.25 mM ABA reached a peak tolerance after a day”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
At 0.01 to 0.25 mM ABA, thermotolerance declined after three days.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“then lost much of the ABA-induced thermotolerance after 3 days”
t0“Cucumber”
e1“Effects of water stress and exogenous abscisic acid (ABA) treatments”
e2“With intact plants, thermotolerance of PA increased significantly”
e3“reirrigated”
e4“1.00 mM ABA”
e5“0.01 to 0.25 mM ABA”
Claim · model-written summary
Authors suggest stress induced endogenous ABA mediates enhanced thermotolerance.
- Taxon
- cucumber
Cucumis sativuse0 - Compound
- ABAe0
- Outcome
- enhanced thermotolerance of PAe0
- Qualifier
- probably mediated through a water-stress-induced increase in endogenous levels of ABAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enhanced thermotolerance of PA in water-stressed cucumber leaves was probably mediated through a water-stress-induced increase in endogenous levels of ABA”
The same questions in other papers
(+)-abscisic acid · disease · Cucumis sativus (cucumber)Positive and negative results
4 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- positive
2 papers more in this group
See all 6 papers →(+)-abscisic acid · tolerance: abiotic · Cucumis sativus (cucumber)Positive and negative results
1 paper in the same direction as this paper · 8 in the opposite direction
- positive
- positive
- positive
6 papers more in this group
See all 10 papers →(+)-abscisic acid · physiology: photosynthesis · Cucumis sativus (cucumber)Results agree
5 papers in the same direction as this paper
- positive
- positive
- positive
2 papers more in this group
See all 6 papers →drought · physiology: photosynthesis · Cucumis sativus (cucumber)Positive and negative results
8 in the opposite direction · 1 reporting no difference from an alternative
- negative
- negative
- negative
6 papers more in this group
See all 10 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.