Abstract
The biophysical basis for the changes in cell elongation rate during gravitropism was examined in aetiolated cucumber (Cucumis sativus L.) hypocotyls. Bulk osmotic pressures on the two sides of the stem and in the epidermal cells were not altered during the early time course of gravitropism. By the pressure-probe technique, a small increase in turgor (0.3 bar, 30 kPa) was detected on the upper (inhibited) side, whereas there was a negligible decrease in turgor on the lower (stimulated) side. These small changes in turgor and water potential appeared to be indirect, passive consequences of the altered growth and the small resistance for water movement from the xylem, and indicated that the change in growth was principally due to changes in wall properties. The results indicate that the hydraulic conductance of the water-transport pathway was large (.25 h-1 bar-1) and the water potential difference supporting cell expansion was no greater than 0.3 bar (30 kPa). From pressure-block experiments, it appeared that upon gravitropic stimulation (1) the yield threshold of the lower half of the stem did not decrease and (2) the wall on the upper side of the stem was not made more rigid by a cross-linking process. Mechanical measurements of the stress/strain properties of the walls showed that the initial development of gravitropism did not involve an alteration of the mechanical behaviour of the isolated walls. Thus, gravitropism in cucumber hypocotyls occurs principally by an alteration of the wall relaxation process, without a necessary change in wall mechanical properties.
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 9
Claim · model-written summary
Bulk osmotic pressures on the two sides of the stem and in the epidermal cells were not altered in the early course of gravitropism.
- Taxon
- cucumber
Cucumis sativust0 - Organ / stage
- steme1
- Outcome
- Bulk osmotic pressurese1
- Direction
- not alterede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Gravitropism of cucumber hypocotyls”
e1“Bulk osmotic pressures on the two sides of the stem and in the epidermal cells were not altered during the early time course of gravitropism”
Claim · model-written summary
A small turgor increase of 0.3 bar (30 kPa) was detected on the upper, inhibited side of the cucumber hypocotyl stem.
- Taxon
- cucumberCucumis sativust0
- Outcome
- turgore2
- Direction
- increasee2
- Value
- 0.3 bar, 30 kPae2
- Qualifier
- upper (inhibited) sidee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Gravitropism of cucumber hypocotyls”
e2“By the pressure-probe technique, a small increase in turgor (0.3 bar, 30 kPa) was detected on the upper (inhibited) side”
Claim · model-written summary
A negligible turgor decrease was found on the lower, stimulated side of the cucumber hypocotyl stem.
- Taxon
- cucumberCucumis sativust0
- Outcome
- turgore3
- Direction
- negligible decreasee3
- Qualifier
- lower (stimulated) sidee3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Gravitropism of cucumber hypocotyls”
e3“whereas there was a negligible decrease in turgor on the lower (stimulated) side”
Claim · model-written summary
The hydraulic conductance of the water-transport pathway in cucumber hypocotyls was large (.25 h-1 bar-1).
- Taxon
- cucumberCucumis sativust0
- Outcome
- hydraulic conductance of the water-transport pathwaye4
- Direction
- largee4
- Value
- .25 h-1 bar-1e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Gravitropism of cucumber hypocotyls”
e4“the hydraulic conductance of the water-transport pathway was large (.25 h-1 bar-1)”
Claim · model-written summary
The water potential difference supporting cell expansion was no greater than 0.3 bar (30 kPa) in cucumber hypocotyls.
- Taxon
- cucumberCucumis sativust0
- Outcome
- water potential difference supporting cell expansione5
- Direction
- no greater thane5
- Value
- 0.3 bar (30 kPa)e5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Gravitropism of cucumber hypocotyls”
e5“the water potential difference supporting cell expansion was no greater than 0.3 bar (30 kPa)”
Claim · model-written summary
Upon gravitropic stimulation the yield threshold of the lower half of the cucumber stem did not decrease.
- Taxon
- cucumberCucumis sativust0
- Outcome
- yield threshold of the lower half of the steme6
- Direction
- did not decreasee6
- Qualifier
- upon gravitropic stimulatione6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Gravitropism of cucumber hypocotyls”
e6“From pressure-block experiments, it appeared that upon gravitropic stimulation (1) the yield threshold of the lower half of the stem did not decrease”
Claim · model-written summary
The wall on the upper side of the cucumber stem was not made more rigid by a cross-linking process during gravitropic stimulation.
- Taxon
- cucumberCucumis sativust0
- Outcome
- wall on the upper side of the steme7
- Direction
- was not made more rigide7
- Qualifier
- a cross-linking processe7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Gravitropism of cucumber hypocotyls”
e7“the wall on the upper side of the stem was not made more rigid by a cross-linking process”
Claim · model-written summary
The initial development of gravitropism did not alter the mechanical behaviour of isolated cucumber hypocotyl walls.
- Taxon
- cucumberCucumis sativust0
- Outcome
- mechanical behaviour of the isolated wallse7
- Direction
- did not involve an alteratione7
- Qualifier
- initial development of gravitropisme7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Gravitropism of cucumber hypocotyls”
e7“the initial development of gravitropism did not involve an alteration of the mechanical behaviour of the isolated walls”
Claim · model-written summary
Gravitropism in cucumber hypocotyls occurs mainly through an alteration of the wall relaxation process rather than a change in wall mechanical properties.
- Taxon
- cucumberCucumis sativust0
- Outcome
- gravitropisme7
- Qualifier
- an alteration of the wall relaxation processe7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Gravitropism of cucumber hypocotyls”
e7“gravitropism in cucumber hypocotyls occurs principally by an alteration of the wall relaxation process, without a necessary change in wall mechanical properties”