Abstract
The concept of ROS as an important factor controlling pollen germination and tube growth has become generally accepted in the last decade. However, the relationship between various ROS and their significance for the success of in vivo germination and fertilization remained unexplored. For the present study, we collected Nicotiana tabacum stigma exudate on different stages of stigma maturity before and after pollination. Electron paramagnetic resonance (EPR) and colorimetric analysis were used to assess levels of O•2− and H2O2 on stigma. Superoxide dismutase activity in the stigma tissues at each stage was evaluated zymographically. As the pistil matured, the level of both ROS decreased markedly, while the activity of SOD increased, and, starting from the second stage, the enzyme was represented by two isozymes: Fe SOD and Cu/Zn SOD, which was demonstrated by the in-gel inhibitory analysis. Selective suppression of Cu/Zn SOD activity shifted the ROS balance, which was confirmed by EPR. This shift markedly reduced the rate of pollen germination in vivo and the fertilization efficiency, which was estimated by the seed set. This result showed that hydrogen peroxide is a necessary component of stigma exudate, accelerates germination and ensures successful reproduction. A decrease in O•2− production due to NADPH oxidase inhibition, although it slowed down germination, did not lead to a noticeable decrease in the seed set. Thus, the role of the superoxide radical can be characterized as less important.
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Claims 9
Claim · model-written summary
Both stigma ROS levels declined as pistils matured.
- Taxon
- Nicotiana tabacum
Nicotiana tabacume1 - Organ / stage
- stigmae1
- Outcome
- level of both ROSe0
- Direction
- decreased markedlye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“As the pistil matured, the level of both ROS decreased markedly”
e1“Nicotiana tabacum stigma exudate on different stages of stigma maturity”
Claim · model-written summary
Stigma SOD activity rose during pistil maturation.
- Taxon
- Nicotiana tabacumNicotiana tabacume1
- Organ / stage
- stigmae1
- Gene
- SODe0
- Outcome
- activity of SODe0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“As the pistil matured, the level of both ROS decreased markedly, while the activity of SOD increased”
e1“Nicotiana tabacum stigma exudate on different stages of stigma maturity”
Claim · model-written summary
Two SOD isozymes were present from the second stage.
- Taxon
- Nicotiana tabacumNicotiana tabacume1
- Organ / stage
- second stagee0
- Gene
- Fe SOD and Cu/Zn SODe0
- Outcome
- two isozymes: Fe SOD and Cu/Zn SODe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“starting from the second stage, the enzyme was represented by two isozymes: Fe SOD and Cu/Zn SOD”
e1“Nicotiana tabacum stigma exudate on different stages of stigma maturity”
Claim · model-written summary
Suppressing Cu/Zn SOD shifted the stigma ROS balance.
- Taxon
- Nicotiana tabacumNicotiana tabacume1
- Treatment
- Selective suppression of Cu/Zn SOD activitye0
- Gene
- Cu/Zn SODe0
- Outcome
- ROS balancee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Selective suppression of Cu/Zn SOD activity shifted the ROS balance”
e1“Nicotiana tabacum stigma exudate on different stages of stigma maturity”
Claim · model-written summary
The ROS shift reduced in vivo pollen germination.
- Taxon
- Nicotiana tabacumNicotiana tabacume2
- Treatment
- Selective suppression of Cu/Zn SOD activitye1
- Outcome
- rate of pollen germination in vivoe0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This shift markedly reduced the rate of pollen germination in vivo”
e1“Selective suppression of Cu/Zn SOD activity shifted the ROS balance”
e2“Nicotiana tabacum stigma exudate on different stages of stigma maturity”
Claim · model-written summary
The ROS shift reduced fertilization efficiency measured by seed set.
- Taxon
- Nicotiana tabacumNicotiana tabacume2
- Treatment
- Selective suppression of Cu/Zn SOD activitye1
- Outcome
- fertilization efficiencye0
- Direction
- reducede0
- Qualifier
- estimated by the seed sete0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This shift markedly reduced the rate of pollen germination in vivo and the fertilization efficiency, which was estimated by the seed set”
e1“Selective suppression of Cu/Zn SOD activity shifted the ROS balance”
e2“Nicotiana tabacum stigma exudate on different stages of stigma maturity”
Claim · model-written summary
The authors infer that hydrogen peroxide promotes germination and successful reproduction.
- Taxon
- Nicotiana tabacumNicotiana tabacume1
- Compound
- hydrogen peroxidee0
- Outcome
- germination and ensures successful reproductione0
- Direction
- acceleratese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“hydrogen peroxide is a necessary component of stigma exudate, accelerates germination and ensures successful reproduction”
e1“Nicotiana tabacum stigma exudate on different stages of stigma maturity”
Claim · model-written summary
NADPH oxidase inhibition slowed pollen germination.
- Taxon
- Nicotiana tabacumNicotiana tabacume1
- Treatment
- NADPH oxidase inhibitione0
- Gene
- NADPH oxidasee0
- Outcome
- germinatione0
- Direction
- slowed downe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A decrease in O•2− production due to NADPH oxidase inhibition, although it slowed down germination”
e1“Nicotiana tabacum stigma exudate on different stages of stigma maturity”
Claim · model-written summary
NADPH oxidase inhibition did not noticeably lower seed set.
- Taxon
- Nicotiana tabacumNicotiana tabacume1
- Treatment
- NADPH oxidase inhibitione0
- Outcome
- seed sete0
- Direction
- did not lead to a noticeable decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A decrease in O•2− production due to NADPH oxidase inhibition, although it slowed down germination, did not lead to a noticeable decrease in the seed set”
e1“Nicotiana tabacum stigma exudate on different stages of stigma maturity”
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