Abstract
Abstract We tested the hypothesis that electrogenic ion pumps, working at the parenchyma symplast/xylem interface of pea hypocotyls, provide the driving force for K + uptake from the xylem. Solutions of known composition were perfused through a hypocotyl segment. The K + activity of the solution flowing out of the xylem (K + out ) increased (i.e. K + uptake decreased) when aerobic respiration was inhibited by lack of O 2 , and this was preceded by a decrease in V px (electrical potential difference between parenchyma symplast and xylem). Perfusion with auxin (1AA) and fusicoccin (FC) stimulated the electrogenic activity of the ‘xylem pumps’ (111 and 205% respectively) and stimulated uptake of K + from the xylem (with 71% and 29% respectively). The close correlation between xylem pump activity and K + uptake corroborated the aforementioned hypothesis. Interestingly, inhibition of pump activity by anoxia was incomplete in the presence of FC. It is thought that FC increases the affinity of the ATP‐requiring xylem pump for ATP, thus ensuring that ATP production during fermentation is sufficient to fuel the pump in the absence of O 2 .
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Claims 8
Claim · model-written summary
Oxygen deprivation increased xylem effluent potassium activity and reduced potassium uptake.
- Taxon
- pea
Lathyrus oleraceuse1 - Treatment
- lack of O 2e0
- Outcome
- K + uptakee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The K + activity of the solution flowing out of the xylem (K + out ) increased (i.e. K + uptake decreased) when aerobic respiration was inhibited by lack of O 2”
e1“pea hypocotyls”
Claim · model-written summary
Oxygen deprivation decreased the electrical potential difference before potassium uptake fell.
- Taxon
- peaLathyrus oleraceuse1
- Outcome
- V pxe0
- Direction
- decreasee0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this was preceded by a decrease in V px (electrical potential difference between parenchyma symplast and xylem)”
e1“pea hypocotyls”
Claim · model-written summary
Auxin stimulated xylem pump electrogenic activity by 111%.
- Taxon
- peaLathyrus oleraceuse1
- Treatment
- auxin (1AA)e0
- Outcome
- electrogenic activity of the ‘xylem pumps’e0
- Direction
- stimulatede0
- Value
- 111e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Perfusion with auxin (1AA) and fusicoccin (FC) stimulated the electrogenic activity of the ‘xylem pumps’ (111 and 205% respectively)”
e1“pea hypocotyls”
Claim · model-written summary
Fusicoccin stimulated xylem pump electrogenic activity by 205%.
- Taxon
- peaLathyrus oleraceuse1
- Treatment
- fusicoccin (FC)e0
- Outcome
- electrogenic activity of the ‘xylem pumps’e0
- Direction
- stimulatede0
- Value
- 205%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Perfusion with auxin (1AA) and fusicoccin (FC) stimulated the electrogenic activity of the ‘xylem pumps’ (111 and 205% respectively)”
e1“pea hypocotyls”
Claim · model-written summary
Auxin stimulated potassium uptake from xylem by 71%.
- Taxon
- peaLathyrus oleraceuse1
- Treatment
- auxin (1AA)e0
- Outcome
- uptake of K + from the xyleme0
- Direction
- stimulatede0
- Value
- 71%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Perfusion with auxin (1AA) and fusicoccin (FC) stimulated the electrogenic activity of the ‘xylem pumps’ (111 and 205% respectively) and stimulated uptake of K + from the xylem (with 71% and 29% respectively)”
e1“pea hypocotyls”
Claim · model-written summary
Fusicoccin stimulated potassium uptake from xylem by 29%.
- Taxon
- peaLathyrus oleraceuse1
- Treatment
- fusicoccin (FC)e0
- Outcome
- uptake of K + from the xyleme0
- Direction
- stimulatede0
- Value
- 29%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Perfusion with auxin (1AA) and fusicoccin (FC) stimulated the electrogenic activity of the ‘xylem pumps’ (111 and 205% respectively) and stimulated uptake of K + from the xylem (with 71% and 29% respectively)”
e1“pea hypocotyls”
Claim · model-written summary
Xylem pump activity was closely correlated with potassium uptake.
- Taxon
- peaLathyrus oleraceuse1
- Organ / stage
- xyleme0
- Outcome
- K + uptakee0
- Qualifier
- close correlatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The close correlation between xylem pump activity and K + uptake”
e1“pea hypocotyls”
Claim · model-written summary
Fusicoccin left pump inhibition by anoxia incomplete.
- Taxon
- peaLathyrus oleraceuse1
- Treatment
- FCe0
- Outcome
- inhibition of pump activity by anoxiae0
- Direction
- incompletee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“inhibition of pump activity by anoxia was incomplete in the presence of FC”
e1“pea hypocotyls”
The same questions in other papers
fusicoccin · nutrient: content · Lathyrus oleraceus (pea)Results agree
2 papers in the same direction as this paper
- positive
- positive
class · nutrient: content · Lathyrus oleraceus (pea)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- no effect
- no effect
- positive
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.