Abstract
Electrical signals presented in plants by action potential and by variation potential (VP) can induce a reversible inactivation of photosynthesis. Changes in the intracellular and extracellular pH during VP generation are a potential mechanism of photosynthetic response induction; however, this hypothesis requires additional experimental investigation. The purpose of the present work was to analyze the influence of pH changes on induction of the photosynthetic response in pumpkin. It was shown that a burning of the cotyledon induced VP propagation into true leaves of pumpkin seedlings inducing a decrease in the photosynthetic CO2 assimilation and an increase in non-photochemical quenching of fluorescence, whereas respiration was activated insignificantly. The photosynthetic response magnitude depended linearly on the VP amplitude. The intracellular and extracellular concentrations of protons were analyzed using pH-sensitive fluorescent probes, and the VP generation was shown to be accompanied by apoplast alkalization (0.4 pH unit) and cytoplasm acidification (0.3 pH unit). The influence of changes in the incubation medium pH on the non-photochemical quenching of fluorescence of isolated chloroplasts was also investigated. It was found that acidification of the medium stimulated the non-photochemical quenching, and the magnitude of this increase depended on the decrease in pH. Our results confirm the contribution of changes in intracellular and extracellular pH to induction of the photosynthetic response caused by VP. Possible mechanisms of the influence of pH changes on photosynthesis are discussed.
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Claims 10
Claim · model-written summary
Cotyledon burning propagated variation potential into pumpkin true leaves.
Not reportedComparatorDirection
Verbatim
e0“a burning of the cotyledon induced VP propagation into true leaves of pumpkin seedlings”
Claim · model-written summary
Cotyledon burning decreased photosynthetic CO2 assimilation in pumpkin true leaves.
- Taxon
- pumpkine0
- Treatment
- burning of the cotyledone0
- Outcome
- photosynthetic CO2 assimilatione0
- Direction
- decreasee0
Not reportedComparator
Verbatim
e0“a burning of the cotyledon induced VP propagation into true leaves of pumpkin seedlings inducing a decrease in the photosynthetic CO2 assimilation”
Claim · model-written summary
Cotyledon burning increased non-photochemical fluorescence quenching in pumpkin true leaves.
- Taxon
- pumpkine0
- Treatment
- burning of the cotyledone0
- Outcome
- non-photochemical quenching of fluorescencee0
- Direction
- increasee0
Not reportedComparator
Verbatim
e0“a burning of the cotyledon induced VP propagation into true leaves of pumpkin seedlings inducing a decrease in the photosynthetic CO2 assimilation and an increase in non-photochemical quenching of fluorescence”
Claim · model-written summary
Respiration was activated insignificantly after cotyledon burning.
Not reportedTreatmentComparator
Verbatim
e0“whereas respiration was activated insignificantly.”
t0“pumpkin seedlings”
Claim · model-written summary
Photosynthetic response magnitude was linearly related to variation potential amplitude.
Not reportedDirection
Verbatim
e0“The photosynthetic response magnitude depended linearly on the VP amplitude.”
t0“pumpkin seedlings”
Claim · model-written summary
Variation potential generation accompanied apoplast alkalization of 0.4 pH unit.
Verbatim
e0“the VP generation was shown to be accompanied by apoplast alkalization (0.4 pH unit) and cytoplasm acidification (0.3 pH unit).”
t0“pumpkin seedlings”
Claim · model-written summary
Variation potential generation accompanied cytoplasm acidification of 0.3 pH unit.
Verbatim
e0“the VP generation was shown to be accompanied by apoplast alkalization (0.4 pH unit) and cytoplasm acidification (0.3 pH unit).”
t0“pumpkin seedlings”
Claim · model-written summary
Acidifying the incubation medium stimulated non-photochemical quenching in isolated chloroplasts.
- Taxon
- pumpkint0
- Treatment
- acidification of the mediume0
- Outcome
- non-photochemical quenchinge0
- Direction
- stimulatede0
Not reportedComparator
Verbatim
e0“acidification of the medium stimulated the non-photochemical quenching, and the magnitude of this increase depended on the decrease in pH.”
t0“pumpkin seedlings”
Claim · model-written summary
The increase in non-photochemical quenching depended on the decrease in medium pH.
Not reportedDirection
Verbatim
e0“the magnitude of this increase depended on the decrease in pH.”
t0“pumpkin seedlings”
Claim · model-written summary
The authors concluded that intracellular and extracellular pH changes contribute to variation-potential-induced photosynthetic responses.
Verbatim
e0“Our results confirm the contribution of changes in intracellular and extracellular pH to induction of the photosynthetic response caused by VP.”
t0“pumpkin seedlings”