Abstract
Total peroxidase, NADH-peroxidase, ascorbate peroxidase, superoxide dismutase, and catalase activities were measured in tobacco (Nicotiana tabacum) leaves and in regenerating and nonregenerating protoplasts isolated from the same tissue and cultured for 2 weeks. The specific ranges of H2O2 concentration at which the enzymes scavenging the active forms of oxygen may efficiently operate and the activities of those enzymes were determined in an extract from tobacco leaves and in dividing and nondividing tobacco mesophyll protoplasts. The overall H2O2-scavenging enzyme activities were similar in both protoplast populations during the 2 to 3 d of culture. After 3 d, the regenerating protoplasts started to divide and both the antioxidant enzyme activities and the total peroxidase activity increased; in contrast, the viability and the H2O2-scavenging enzyme activities in nonregenerating protoplasts dramatically decreased. Surprisingly, the regenerative potentiality in dividing protoplasts was specifically correlated with a higher NADH-peroxidase activity, which resulted in a net H2O2 accumulation in the cells. Light, which causes the accumulation of active forms of oxygen in photosynthetic organelles, also stimulated catalase and ascorbate peroxidase activities in dividing protoplasts. We suggest that the localization of H2O2 rather than its absolute concentration might be responsible for oxidative stress and that controlled amounts of H2O2 are necessary to allow proper cell-wall reconstitution and the consequent cell division.
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Claims 9
Claim · model-written summary
Overall peroxide-scavenging enzyme activities were similar in regenerating and nonregenerating protoplasts during the first 2 to 3 days.
- Taxon
- tobacco
Nicotiana tabacume1 - Outcome
- H2O2-scavenging enzyme activitiese0
- Direction
- similare0
- Qualifier
- during the 2 to 3 d of culturee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The overall H2O2-scavenging enzyme activities were similar in both protoplast populations during the 2 to 3 d of culture”
e1“tobacco (Nicotiana tabacum)”
Claim · model-written summary
Regenerating protoplasts began dividing after three days.
- Taxon
- tobaccoNicotiana tabacume1
- Organ / stage
- protoplastse0
- Outcome
- regenerating protoplasts started to dividee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After 3 d, the regenerating protoplasts started to divide”
e1“tobacco (Nicotiana tabacum)”
Claim · model-written summary
Antioxidant enzyme and total peroxidase activities increased in regenerating protoplasts.
- Taxon
- tobaccoNicotiana tabacume1
- Outcome
- antioxidant enzyme activities and the total peroxidase activitye0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“both the antioxidant enzyme activities and the total peroxidase activity increased”
e1“tobacco (Nicotiana tabacum)”
Claim · model-written summary
Viability and peroxide-scavenging enzyme activities decreased in nonregenerating protoplasts.
- Taxon
- tobaccoNicotiana tabacume1
- Outcome
- viability and the H2O2-scavenging enzyme activitiese0
- Direction
- dramatically decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the viability and the H2O2-scavenging enzyme activities in nonregenerating protoplasts dramatically decreased”
e1“tobacco (Nicotiana tabacum)”
Claim · model-written summary
Regenerative potential correlated with higher NADH-peroxidase activity.
- Taxon
- tobaccoNicotiana tabacume1
- Gene
- NADH-peroxidasee0
- Outcome
- regenerative potentialitye0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the regenerative potentiality in dividing protoplasts was specifically correlated with a higher NADH-peroxidase activity”
e1“tobacco (Nicotiana tabacum)”
Claim · model-written summary
Higher NADH-peroxidase activity resulted in net cellular peroxide accumulation.
- Taxon
- tobaccoNicotiana tabacume1
- Gene
- NADH-peroxidasee0
- Outcome
- H2O2 accumulation in the cellse0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a higher NADH-peroxidase activity, which resulted in a net H2O2 accumulation in the cells”
e1“tobacco (Nicotiana tabacum)”
Claim · model-written summary
Light stimulated catalase and ascorbate peroxidase activities in dividing protoplasts.
- Taxon
- tobaccoNicotiana tabacume1
- Treatment
- Lighte0
- Outcome
- catalase and ascorbate peroxidase activitiese0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Light, which causes the accumulation of active forms of oxygen in photosynthetic organelles, also stimulated catalase and ascorbate peroxidase activities in dividing protoplasts”
e1“tobacco (Nicotiana tabacum)”
Claim · model-written summary
The authors suggest peroxide localization may govern oxidative stress.
- Taxon
- tobaccoNicotiana tabacume1
- Outcome
- oxidative stresse0
- Qualifier
- localization of H2O2 rather than its absolute concentratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the localization of H2O2 rather than its absolute concentration might be responsible for oxidative stress”
e1“tobacco (Nicotiana tabacum)”
Claim · model-written summary
The authors suggest controlled peroxide amounts are needed for cell-wall reconstitution and division.
- Taxon
- tobaccoNicotiana tabacume1
- Outcome
- cell-wall reconstitution and the consequent cell divisione0
- Qualifier
- controlled amounts of H2O2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“controlled amounts of H2O2 are necessary to allow proper cell-wall reconstitution and the consequent cell division”
e1“tobacco (Nicotiana tabacum)”
The same questions in other papers
light · physiology: antioxidant enzymes · Nicotiana tabacum (tobacco)Positive and negative results
4 papers in the same direction as this paper · 1 reporting no difference from an alternative
- no effect
- positive
- positive
2 papers more in this group
See all 6 papers →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.