Abstract
The effects of exogenous phytohormones (IAA, ABA, and GA 3 ) on the intracellular (cytoplasmic) pH (pH c ) in ungerminating and germinating petunia ( Petunia hybrida L.) pollen grains were studied. The pH c values were measured with fluorescein diacetate. In ungerminating pollen grains, all phytohormones reduced pH c relatively rapidly; after 10–15 min, initial value was restored. In germinating pollen grains, IAA and ABA induced a relatively rapid cytosol alkalization, which was not reversed during experiment. GA 3 acidified the cytosol, i.e., exerted the effect similar to that in ungerminating pollen grains. Sodium orthovanadate suppressed completely the hormone-induced pH c shift toward alkaline values in germinating pollen grains, whereas this inhibitor did not affect pH c in the absence of phytohormones. Sodium orthovanadate also slowed the recovery of pH c after hormone-induced cytoplasm acidification in ungerminating pollen grains, reduced pH c in control ungerminating grains, and weakened substantially the effects of all phytohormones on these pollen grains. On the basis of these results, we suggested that physiological activities of phytohormones in this system were mediated by pH c modulation, namely, a transient disturbance in the cytosolic pH homeostasis, which could trigger further phytohormone-induced cell responses. We concluded that a hormone-induced cytoplasm alkalization in pollen grains was mediated by the activity of their plasma membrane H + -ATPase and that this proton pump was involved in the control of pH c in both germinating and ungerminating pollen grains.
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Claims 10
Claim · model-written summary
In ungerminating pollen grains, all exogenous phytohormones reduced cytoplasmic pH rapidly, and the initial value was restored after 10–15 min.
- Taxon
- Petunia hybrida
Petunia ×hybridat0 - Organ / stage
- ungerminating pollen grainse1
- Treatment
- exogenous phytohormonese0
- Outcome
- pH ce1
- Direction
- reducede1
- Comparator
- initial valuee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e0“exogenous phytohormones (IAA, ABA, and GA 3 )”
e1“In ungerminating pollen grains, all phytohormones reduced pH c relatively rapidly; after 10–15 min, initial value was restored”
Claim · model-written summary
IAA and ABA induced a rapid cytosol alkalization in germinating pollen grains that was not reversed during the experiment.
- Taxon
- Petunia hybridaPetunia ×hybridat0
- Organ / stage
- germinating pollen grainse2
- Treatment
- IAA and ABAe2
- Outcome
- cytosol alkalizatione2
- Direction
- inducede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e2“In germinating pollen grains, IAA and ABA induced a relatively rapid cytosol alkalization, which was not reversed during experiment”
Claim · model-written summary
GA 3 acidified the cytosol of germinating pollen grains, similar to the effect in ungerminating pollen grains.
- Taxon
- Petunia hybridaPetunia ×hybridat0
- Treatment
- GA 3e3
- Outcome
- cytosole3
- Direction
- acidifiede3
- Comparator
- ungerminating pollen grainse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e3“GA 3 acidified the cytosol, i.e., exerted the effect similar to that in ungerminating pollen grains”
Claim · model-written summary
Sodium orthovanadate suppressed the hormone-induced cytosolic pH shift toward alkaline values in germinating pollen grains.
- Taxon
- Petunia hybridaPetunia ×hybridat0
- Organ / stage
- germinating pollen grainse4
- Treatment
- Sodium orthovanadatee4
- Outcome
- hormone-induced pH c shift toward alkaline valuese4
- Direction
- suppressede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e4“Sodium orthovanadate suppressed completely the hormone-induced pH c shift toward alkaline values in germinating pollen grains, whereas this inhibitor did not affect pH c in the absence of phytohormones”
Claim · model-written summary
Sodium orthovanadate did not affect cytosolic pH in the absence of phytohormones.
- Taxon
- Petunia hybridaPetunia ×hybridat0
- Treatment
- Sodium orthovanadatee4
- Outcome
- pH ce4
- Direction
- did not affecte4
- Comparator
- in the absence of phytohormonese4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e4“Sodium orthovanadate suppressed completely the hormone-induced pH c shift toward alkaline values in germinating pollen grains, whereas this inhibitor did not affect pH c in the absence of phytohormones”
Claim · model-written summary
Sodium orthovanadate slowed the recovery of cytosolic pH after hormone-induced acidification in ungerminating pollen grains.
- Taxon
- Petunia hybridaPetunia ×hybridat0
- Organ / stage
- ungerminating pollen grainse5
- Treatment
- Sodium orthovanadatee5
- Outcome
- recovery of pH ce5
- Direction
- slowede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e5“Sodium orthovanadate also slowed the recovery of pH c after hormone-induced cytoplasm acidification in ungerminating pollen grains”
Claim · model-written summary
Sodium orthovanadate reduced cytosolic pH in control ungerminating pollen grains.
- Taxon
- Petunia hybridaPetunia ×hybridat0
- Treatment
- Sodium orthovanadatee6
- Outcome
- pH ce6
- Direction
- reducede6
- Comparator
- control ungerminating grainse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e6“Sodium orthovanadate also slowed the recovery of pH c after hormone-induced cytoplasm acidification in ungerminating pollen grains, reduced pH c in control ungerminating grains”
Claim · model-written summary
Sodium orthovanadate substantially weakened the effects of all phytohormones on ungerminating pollen grains.
- Taxon
- Petunia hybridaPetunia ×hybridat0
- Treatment
- Sodium orthovanadatee7
- Outcome
- effects of all phytohormonese7
- Direction
- weakened substantiallye7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e7“Sodium orthovanadate also slowed the recovery of pH c after hormone-induced cytoplasm acidification in ungerminating pollen grains, reduced pH c in control ungerminating grains, and weakened substantially the effects of all phytohormones on these pollen grains”
Claim · model-written summary
The authors suggest that the physiological activities of phytohormones are mediated by cytosolic pH modulation.
- Taxon
- Petunia hybridaPetunia ×hybridat0
- Outcome
- physiological activities of phytohormonese2
- Qualifier
- pH c modulatione2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e2“physiological activities of phytohormones in this system were mediated by pH c modulation”
Claim · model-written summary
The authors conclude that the hormone-induced cytoplasm alkalization in pollen grains is mediated by plasma membrane H+-ATPase activity.
- Taxon
- Petunia hybridaPetunia ×hybridat0
- Gene
- plasma membrane H + -ATPasee2
- Outcome
- hormone-induced cytoplasm alkalization in pollen grainse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Petunia hybrida pollen grains”
e2“We concluded that a hormone-induced cytoplasm alkalization in pollen grains was mediated by the activity of their plasma membrane H + -ATPase”