Abstract
Interactions between putrescine and membrane function were examined with the use of a recently developed microelectrode system that enables us simultaneously to quantify membrane potentials and net K(+) fluxes associated with individual cells at the root surface of an intact corn (Zea mays L.) seedling. In contrast to the results of others, our analyses indicate that exogenous putrescine (0.5 millimolar), in the absence of calcium, does not maintain membrane stability. In addition, putrescine caused a wound response characterized by a gradual depolarization of the membrane potential and a considerable net efflux of K(+) from the root. In the presence of calcium, both short term (20 minutes) and long term (24 hours) exposure to a high concentration of exogenous putrescine (5 millimolar) also caused a reduction in the resting membrane potential and a significant K(+) efflux. However, preincubating corn roots in a solution containing the antioxidant ascorbate ameliorated the wounding effects of putrescine and slightly increased potassium uptake. A similar preincubation in the absence of calcium did not protect membranes against putrescine-induced damage. The ameliorating effect of ascorbate on putrescine-induced membrane damage suggests that the wounding response of high putrescine levels in corn roots involves the catabolism of the polyamine by a cell wall diamine oxidase, with the concomitant production of hydrogen peroxide and free radicals resulting in peroxidative damage of the plasmalemma.
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Claims 9
Claim · model-written summary
Putrescine without calcium did not maintain corn root membrane stability.
- Treatment
- exogenous putrescine (0.5 millimolar)e0
- Outcome
- membrane stabilitye0
- Direction
- does not maintaine0
- Qualifier
- in the absence of calciume0
Not reportedTaxonComparator
Verbatim
e0“exogenous putrescine (0.5 millimolar), in the absence of calcium, does not maintain membrane stability”
Claim · model-written summary
Putrescine gradually depolarized corn root membrane potential.
Not reportedTaxonComparator
Verbatim
e0“putrescine caused a wound response characterized by a gradual depolarization of the membrane potential”
Claim · model-written summary
Putrescine caused considerable net potassium efflux from corn roots.
Not reportedTaxonComparator
Verbatim
e0“putrescine caused a wound response characterized by a gradual depolarization of the membrane potential and a considerable net efflux of K(+) from the root”
Claim · model-written summary
High putrescine with calcium reduced resting membrane potential after short and long exposure.
- Treatment
- exogenous putrescine (5 millimolar)e0
- Outcome
- resting membrane potentiale0
- Direction
- reductione0
- Qualifier
- both short term (20 minutes) and long term (24 hours)e0
Not reportedTaxonComparator
Verbatim
e0“In the presence of calcium, both short term (20 minutes) and long term (24 hours) exposure to a high concentration of exogenous putrescine (5 millimolar) also caused a reduction in the resting membrane potential”
Claim · model-written summary
High putrescine with calcium caused significant potassium efflux.
Not reportedTaxonComparator
Verbatim
e0“In the presence of calcium, both short term (20 minutes) and long term (24 hours) exposure to a high concentration of exogenous putrescine (5 millimolar) also caused a reduction in the resting membrane potential and a significant K(+) efflux”
Claim · model-written summary
Ascorbate preincubation ameliorated putrescine wounding of corn roots.
- Taxon
- corn
Zea mays subsp. mayse0 - Treatment
- ascorbatee0
- Outcome
- wounding effects of putrescinee0
- Direction
- amelioratede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“preincubating corn roots in a solution containing the antioxidant ascorbate ameliorated the wounding effects of putrescine”
Claim · model-written summary
Ascorbate preincubation slightly increased potassium uptake.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- ascorbatee0
- Outcome
- potassium uptakee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“preincubating corn roots in a solution containing the antioxidant ascorbate ameliorated the wounding effects of putrescine and slightly increased potassium uptake”
Claim · model-written summary
Without calcium, ascorbate preincubation did not protect membranes from putrescine damage.
- Treatment
- preincubatione0
- Outcome
- membranes against putrescine-induced damagee0
- Direction
- did not protecte0
- Qualifier
- in the absence of calciume0
Not reportedTaxonComparator
Verbatim
e0“A similar preincubation in the absence of calcium did not protect membranes against putrescine-induced damage”
Claim · model-written summary
Authors propose putrescine catabolism and oxidative damage as the wounding mechanism.
- Taxon
- cornZea mays subsp. mayse0
- Gene
- cell wall diamine oxidasee0
- Compound
- hydrogen peroxidee0
- Outcome
- peroxidative damage of the plasmalemmae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the wounding response of high putrescine levels in corn roots involves the catabolism of the polyamine by a cell wall diamine oxidase, with the concomitant production of hydrogen peroxide and free radicals resulting in peroxidative damage of the plasmalemma”
The same questions in other papers
putrescine · physiology: oxidative · Zea mays (maize)Positive and negative results
1 paper in the same direction as this paper · 2 in the opposite direction
- positive
- positive
- 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.