Abstract
"Cavitation fatigue" is the increased susceptibility of a xylem conduit to cavitation as a result of its prior cavitation. It was investigated whether cavitation fatigue induced in vivo could be repaired in intact plants. Sunflowers (Helianthus annuus L.) were subjected to soil drought in the greenhouse. Native embolism and vulnerability to cavitation was measured in well-watered controls and after 5 d and 10 d of controlled drought. A dramatic cavitation fatigue was observed where droughted xylem that was refilled in the laboratory developed up to 60 PLC (percentage loss of hydraulic conductivity) at -1 MPa versus only 5.2 PLC in non-droughted controls. Rewatered plants showed the complete reversal of cavitation fatigue over 4 d. Reversal of fatigue was correlated with the refilling of embolized vessels in the intact plants (r(2)=0.91, P<0.01), suggesting that xylem transport to fatigued vessels was required for their repair. The in vivo reversal of fatigue was partially duplicated in excised stem segments by perfusing them with root exudates from droughted (DR) and well-watered (WW) plants. The DR exudate had a greater effect, and this was associated with a greater pH in the DR versus WW saps, but there was no difference in total cation concentration. Perfusions with 2 mM CaCl(2) and KCl solutions also partially reversed cavitation fatigue as opposed to no effect with deionized water, suggesting a role of ions in addition to a pH effect. It is suspected that fatigue is caused by stretching and partial disruption of linkages between cellulose microfibrils in inter-conduit pit membranes during air seeding, and that the reversal of fatigue involves restoring these linkages by ingredients in xylem sap.
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Claims 11
Claim · model-written summary
Droughted sunflower xylem showed greater cavitation fatigue than nondroughted controls, reaching 60 versus 5.2 PLC at -1 MPa.
- Taxon
- sunflower
Helianthus annuust0 - Treatment
- droughtede0
- Outcome
- PLC (percentage loss of hydraulic conductivity)e0
- Direction
- up toe0
- Value
- 60 PLCe0
- Qualifier
- 5.2 PLCe0
- Comparator
- non-droughted controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“droughted xylem that was refilled in the laboratory developed up to 60 PLC (percentage loss of hydraulic conductivity) at -1 MPa versus only 5.2 PLC in non-droughted controls”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
Rewatering completely reversed sunflower cavitation fatigue over four days.
- Taxon
- sunflowerHelianthus annuust0
- Treatment
- Rewaterede0
- Outcome
- cavitation fatiguee0
- Direction
- complete reversale0
- Value
- 4 de0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rewatered plants showed the complete reversal of cavitation fatigue over 4 d.”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
Reversal of cavitation fatigue correlated with refilling of embolized vessels.
- Taxon
- sunflowerHelianthus annuust0
- Organ / stage
- embolized vesselse0
- Outcome
- Reversal of fatiguee0
- Value
- r(2)=0.91e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reversal of fatigue was correlated with the refilling of embolized vessels in the intact plants (r(2)=0.91, P<0.01)”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
Root exudates partially reversed cavitation fatigue in excised sunflower stems.
- Taxon
- sunflowerHelianthus annuust0
- Organ / stage
- excised stem segmentse0
- Treatment
- perfusing them with root exudatese0
- Outcome
- reversal of fatiguee0
- Direction
- partially duplicatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The in vivo reversal of fatigue was partially duplicated in excised stem segments by perfusing them with root exudates from droughted (DR) and well-watered (WW) plants.”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
Droughted-plant exudate had a greater reversal effect than well-watered-plant exudate.
- Taxon
- sunflowerHelianthus annuust0
- Treatment
- DR exudatee0
- Outcome
- greater effecte0
- Direction
- greatere0
- Comparator
- well-watered (WW)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The DR exudate had a greater effect”
e1“root exudates from droughted (DR) and well-watered (WW) plants”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
Droughted-plant sap had higher pH than well-watered-plant sap.
- Taxon
- sunflowerHelianthus annuust0
- Outcome
- pHe0
- Direction
- greatere0
- Comparator
- WW sapse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a greater pH in the DR versus WW saps”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
Total cation concentration did not differ between droughted and well-watered sap.
- Taxon
- sunflowerHelianthus annuust0
- Outcome
- total cation concentratione0
- Direction
- no differencee0
- Comparator
- WW sapse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was no difference in total cation concentration”
e1“the DR versus WW saps”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
Calcium chloride perfusion partially reversed cavitation fatigue relative to deionized water.
- Taxon
- sunflowerHelianthus annuust0
- Treatment
- 2 mM CaCl(2)e0
- Outcome
- cavitation fatiguee0
- Direction
- partially reversede0
- Comparator
- deionized watere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Perfusions with 2 mM CaCl(2) and KCl solutions also partially reversed cavitation fatigue as opposed to no effect with deionized water”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
Potassium chloride perfusion partially reversed cavitation fatigue relative to deionized water.
- Taxon
- sunflowerHelianthus annuust0
- Treatment
- KCl solutionse0
- Outcome
- cavitation fatiguee0
- Direction
- partially reversede0
- Comparator
- deionized watere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Perfusions with 2 mM CaCl(2) and KCl solutions also partially reversed cavitation fatigue as opposed to no effect with deionized water”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
The authors suspect cavitation fatigue arises from disrupted links between cellulose microfibrils in pit membranes.
- Taxon
- sunflowerHelianthus annuust0
- Outcome
- fatiguee0
- Qualifier
- stretching and partial disruption of linkages between cellulose microfibrilse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“fatigue is caused by stretching and partial disruption of linkages between cellulose microfibrils in inter-conduit pit membranes”
t0“sunflower (Helianthus annuus L.)”
Claim · model-written summary
The authors suspect components of xylem sap restore microfibril links during fatigue reversal.
- Taxon
- sunflowerHelianthus annuust0
- Outcome
- reversal of fatiguee0
- Qualifier
- restoring these linkages by ingredients in xylem sape0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the reversal of fatigue involves restoring these linkages by ingredients in xylem sap”
t0“sunflower (Helianthus annuus L.)”
The same questions in other papers
drought · soil: physics · Helianthus annuus (common sunflower)Results agree
3 papers in the same direction as this paper
- negative
- negative
- negative
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.