Abstract
The phytotoxin fusicoccin (FC) was found to induce an increase in apoplastic H₂O₂ content in Arabidopsis thaliana cells, apparently linked to the presence of an as yet unidentified catalase inhibitor detectable even in the external medium of FC-treated cells. This study, aimed to further characterize the inhibitor's features, shows that (1) FC-induced H₂O₂ accumulation increases as a function of FC concentration and correlates to the amount of inhibitor released at apoplastic level. The pattern of H+ efflux, conversely, does not fit with that of these two parameters, suggesting that neither the production nor the release of the catalase inhibitor is linked to the main role of FC in activating the plasma membrane (PM) H+-ATPase; (2) treatment with 10 µM erythrosine B (EB) early and totally inhibits net H+ and K+ fluxes across the PM, indicative of the H+ pump activity; nevertheless, also in these conditions a huge FC-induced H₂O₂ accumulation occurs, confirming that this effect is not related to the FC-induced PM H+-ATPase activation; (3) the inhibitor's release increases with time in all conditions tested and is markedly affected by extracellular pH (a higher pH value being associated to a larger efflux), in agreement with a weak acid release; and (4) the inhibitor can be almost completely recovered in a CH₂C₂-soluble fraction extracted from the incubation medium by sequential acid-base partitioning which contains nearly all of the organic acids released. These final results strongly suggest that the metabolite responsible for the FC-induced catalase inhibition belongs to the organic acid class.
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Claims 10
Claim · model-written summary
Fusicoccin induced higher apoplastic hydrogen peroxide in Arabidopsis cells.
- Taxon
- Arabidopsis thaliana
Arabidopsis thalianae0 - Treatment
- fusicoccine0
- Outcome
- apoplastic H₂O₂ contente0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The phytotoxin fusicoccin (FC) was found to induce an increase in apoplastic H₂O₂ content in Arabidopsis thaliana cells”
t0“Arabidopsis thaliana cells”
Claim · model-written summary
Fusicoccin-induced hydrogen peroxide accumulation increased with fusicoccin concentration.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- FC concentratione0
- Outcome
- H₂O₂ accumulatione0
- Direction
- increasese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“FC-induced H₂O₂ accumulation increases as a function of FC concentration”
t0“Arabidopsis thaliana cells”
Claim · model-written summary
Hydrogen peroxide accumulation correlated with the amount of inhibitor released apoplastically.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- FCe1
- Outcome
- H₂O₂ accumulatione1
- Qualifier
- amount of inhibitor released at apoplastic levele0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“correlates to the amount of inhibitor released at apoplastic level”
t0“Arabidopsis thaliana cells”
e1“FC-induced H₂O₂ accumulation increases as a function of FC concentration”
Claim · model-written summary
The hydrogen ion efflux pattern did not match peroxide accumulation or inhibitor release.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- FCe1
- Outcome
- H+ effluxe0
- Direction
- does not fite0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The pattern of H+ efflux, conversely, does not fit with that of these two parameters”
t0“Arabidopsis thaliana cells”
e1“The phytotoxin fusicoccin (FC) was found to induce an increase in apoplastic H₂O₂ content in Arabidopsis thaliana cells”
Claim · model-written summary
Erythrosine B inhibited net hydrogen and potassium ion fluxes across the plasma membrane.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Treatment
- 10 µM erythrosine B (EB)e0
- Outcome
- net H+ and K+ fluxes across the PMe0
- Direction
- inhibitse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“treatment with 10 µM erythrosine B (EB) early and totally inhibits net H+ and K+ fluxes across the PM”
t0“Arabidopsis thaliana cells”
Claim · model-written summary
Fusicoccin still induced large hydrogen peroxide accumulation when erythrosine B blocked ion fluxes.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Outcome
- FC-induced H₂O₂ accumulatione0
- Qualifier
- also in these conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nevertheless, also in these conditions a huge FC-induced H₂O₂ accumulation occurs”
t0“Arabidopsis thaliana cells”
Claim · model-written summary
Inhibitor release increased over time across tested conditions.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Outcome
- inhibitor's releasee0
- Direction
- increasese0
- Setting
- all conditions testede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the inhibitor's release increases with time in all conditions tested”
t0“Arabidopsis thaliana cells”
Claim · model-written summary
Higher extracellular pH was associated with more inhibitor efflux.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Outcome
- effluxe0
- Direction
- largere0
- Setting
- higher pH valuee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a higher pH value being associated to a larger efflux”
t0“Arabidopsis thaliana cells”
Claim · model-written summary
The inhibitor was almost completely recovered in an organic acid-containing soluble fraction.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Outcome
- inhibitor can be almost completely recoverede0
- Qualifier
- CH₂C₂-soluble fractione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the inhibitor can be almost completely recovered in a CH₂C₂-soluble fraction extracted from the incubation medium by sequential acid-base partitioning which contains nearly all of the organic acids released”
t0“Arabidopsis thaliana cells”
Claim · model-written summary
The authors infer that the catalase-inhibiting metabolite belongs to the organic acid class.
- Taxon
- Arabidopsis thalianaArabidopsis thalianat0
- Compound
- organic acide0
- Outcome
- FC-induced catalase inhibitione0
- Qualifier
- metabolite responsiblee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the metabolite responsible for the FC-induced catalase inhibition belongs to the organic acid class”
t0“Arabidopsis thaliana cells”