Abstract
Abstract Tobacco plants were grown in plant chambers for four weeks, then exposed to one of the following treatments for 4 days: (1) daily supplementary UV-B radiation corresponding to 6.9 kJ m −2 d −1 biologically effective dose (UV-B), (2) daily irrigation with 0.1 mM hydrogen peroxide, or (3) a parallel application of the two treatments (UV-B + H 2 O 2 ). Neither the H 2 O 2 nor the UV-B treatments were found to be damaging to leaf photosynthesis. Both single factor treatments increased leaf H 2 O 2 contents but had distinct effects on various H 2 O 2 neutralising mechanisms. Non-enzymatic H 2 O 2 antioxidant capacities were increased by direct H 2 O 2 treatment only, but not by UV-B. In contrast, enzymatic H 2 O 2 neutralisation was mostly increased by UV-B, the responses showing an interesting diversity. When class-III peroxidase (POD) activity was assayed using an artificial substrate (ABTS, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)), both treatments appeared to have a positive effect. However, only UV-B-treated leaves showed higher POD activities when phenolic compounds naturally occurring in tobacco leaves (chlorogenic acid or quercetin) were used as substrates. These results demonstrate a substrate-dependent, functional heterogeneity in POD and further suggest that the selective activation of specific isoforms in UV-B acclimated leaves is not triggered by excess H 2 O 2 in these leaves.
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Claims 10
Claim · model-written summary
Hydrogen peroxide treatment did not damage tobacco leaf photosynthesis.
- Taxon
- Tobacco
Nicotiana tabacume1 - Treatment
- H 2 O 2e0
- Outcome
- leaf photosynthesise0
- Direction
- Neithere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither the H 2 O 2 nor the UV-B treatments were found to be damaging to leaf photosynthesis”
e1“Tobacco plants”
Claim · model-written summary
UV-B treatment did not damage tobacco leaf photosynthesis.
- Taxon
- TobaccoNicotiana tabacume1
- Treatment
- UV-Be0
- Outcome
- leaf photosynthesise0
- Direction
- Neithere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Neither the H 2 O 2 nor the UV-B treatments were found to be damaging to leaf photosynthesis”
e1“Tobacco plants”
Claim · model-written summary
Hydrogen peroxide treatment increased tobacco leaf peroxide content.
- Taxon
- TobaccoNicotiana tabacume2
- Treatment
- daily irrigation with 0.1 mM hydrogen peroxidee1
- Outcome
- leaf H 2 O 2 contentse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both single factor treatments increased leaf H 2 O 2 contents”
e1“daily irrigation with 0.1 mM hydrogen peroxide”
e2“Tobacco plants”
Claim · model-written summary
UV-B treatment increased tobacco leaf peroxide content.
- Taxon
- TobaccoNicotiana tabacume2
- Treatment
- daily supplementary UV-B radiatione1
- Outcome
- leaf H 2 O 2 contentse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both single factor treatments increased leaf H 2 O 2 contents”
e1“daily supplementary UV-B radiation”
e2“Tobacco plants”
Claim · model-written summary
Direct peroxide treatment increased nonenzymatic antioxidant capacity.
- Taxon
- TobaccoNicotiana tabacume1
- Treatment
- direct H 2 O 2 treatmente0
- Outcome
- Non-enzymatic H 2 O 2 antioxidant capacitiese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Non-enzymatic H 2 O 2 antioxidant capacities were increased by direct H 2 O 2 treatment only, but not by UV-B”
e1“Tobacco plants”
Claim · model-written summary
UV-B did not increase nonenzymatic peroxide antioxidant capacity.
- Taxon
- TobaccoNicotiana tabacume1
- Treatment
- UV-Be0
- Outcome
- Non-enzymatic H 2 O 2 antioxidant capacitiese0
- Direction
- not by UV-Be0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Non-enzymatic H 2 O 2 antioxidant capacities were increased by direct H 2 O 2 treatment only, but not by UV-B”
e1“Tobacco plants”
Claim · model-written summary
UV-B mostly increased enzymatic peroxide neutralization in tobacco leaves.
- Taxon
- TobaccoNicotiana tabacume1
- Treatment
- UV-Be0
- Outcome
- enzymatic H 2 O 2 neutralisatione0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“enzymatic H 2 O 2 neutralisation was mostly increased by UV-B”
e1“Tobacco plants”
Claim · model-written summary
Both peroxide and UV-B treatments raised POD activity when measured with ABTS.
- Taxon
- TobaccoNicotiana tabacume1
- Treatment
- both treatmentse0
- Outcome
- class-III peroxidase (POD) activitye0
- Direction
- positive effecte0
- Qualifier
- artificial substratee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When class-III peroxidase (POD) activity was assayed using an artificial substrate (ABTS, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)), both treatments appeared to have a positive effect”
e1“Tobacco plants”
Claim · model-written summary
Only UV-B treatment raised POD activity when chlorogenic acid or quercetin was used as substrate.
- Taxon
- tobaccoNicotiana tabacume0
- Treatment
- UV-B-treatede0
- Outcome
- POD activitiese0
- Direction
- highere0
- Qualifier
- chlorogenic acid or quercetine0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“only UV-B-treated leaves showed higher POD activities when phenolic compounds naturally occurring in tobacco leaves (chlorogenic acid or quercetin) were used as substrates”
Claim · model-written summary
The distinct substrate responses imply functional heterogeneity in tobacco POD and suggest selective isoform activation by UV-B is not triggered by excess leaf peroxide.
- Taxon
- tobaccoNicotiana tabacume1
- Outcome
- selective activation of specific isoformse0
- Qualifier
- not triggered by excess H 2 O 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These results demonstrate a substrate-dependent, functional heterogeneity in POD and further suggest that the selective activation of specific isoforms in UV-B acclimated leaves is not triggered by excess H 2 O 2 in these leaves”
e1“tobacco leaves”
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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.