Abstract
Chloroplast-encoded NDH polypeptides (components of the plastid Ndh complex) and the NADH dehydrogenase activity of the Ndh complex (NADH-DH) increased under photooxidative stress. The possible involvement of H2O2-mediated signaling in the photooxidative induction of chloroplastic ndh genes was thoroughly studied. We have analyzed the changes in the NADH-DH and steady-state levels of NDH-F polypeptide and ndhB and ndhF transcripts in barley (Hordeum vulgare cv Hassan) leaves. Subapical leaf segments were incubated in growing light (GL), photooxidative light (PhL), GL and H2O2 (GL + H2O2), or PhL and 50 nM paraquat in the incubation medium. Treatments with H2O2 under GL mimicked the photooxidative stimulus, causing a dose-dependent increase of NADH-DH and NDH-F polypeptide. The kinetic of Ndh complex induction was further studied in leaves pre-incubated with or without the H2O2-scavenger dimethyltiourea. NADH-DH and NDH-F polypeptide rapidly increased up to 16 h in PhL, GL+ H2O2, and, at higher rate, in PhL and paraquat. The observed increases of NADH-DH and NDH-F after 4 h in PhL and GL + H2O2 were not accompanied by significant changes in ndhB and ndhF transcripts. However, at 16-h incubations NADH-DH and NDH-F changes closely correlated with higher ndhB and ndhF transcript levels. All these effects were prevented by dimethylthiourea. It is proposed that the induction of chloroplastic ndh genes under photooxidative stress is mediated by H2O2 through mechanisms that involve a rapid translation of pre-existing transcripts and the increase of the ndh transcript levels.
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Claims 8
Claim · model-written summary
Chloroplast-encoded NDH polypeptides and NADH dehydrogenase activity of the Ndh complex increased under photooxidative stress in barley.
- Taxon
- Barley
.jpg?width=60)
Hordeum vulgaret0 - Treatment
- photooxidative stresse0
- Outcome
- NADH dehydrogenase activitye0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Chloroplast-encoded NDH polypeptides (components of the plastid Ndh complex) and the NADH dehydrogenase activity of the Ndh complex (NADH-DH) increased under photooxidative stress”
t0“Barley”
Claim · model-written summary
Treatment with H2O2 under growing light mimicked photooxidative stress, causing a dose-dependent increase of NADH-DH and NDH-F polypeptide in barley leaves.
- Taxon
- BarleyHordeum vulgaret0
- Treatment
- H2O2 under GLe0
- Outcome
- NADH-DH and NDH-F polypeptidee0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatments with H2O2 under GL mimicked the photooxidative stimulus, causing a dose-dependent increase of NADH-DH and NDH-F polypeptide”
t0“Barley”
Claim · model-written summary
NADH-DH and NDH-F polypeptide rapidly increased up to 16 h in photooxidative light and in growing light with H2O2.
- Taxon
- BarleyHordeum vulgaret0
- Treatment
- PhL, GL+ H2O2e0
- Outcome
- NADH-DH and NDH-F polypeptidee0
- Direction
- rapidly increasede0
- Qualifier
- up to 16 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NADH-DH and NDH-F polypeptide rapidly increased up to 16 h in PhL, GL+ H2O2, and, at higher rate, in PhL and paraquat”
t0“Barley”
Claim · model-written summary
NADH-DH and NDH-F increased at a higher rate in photooxidative light with paraquat.
- Taxon
- BarleyHordeum vulgaret0
- Treatment
- PhL and paraquate0
- Outcome
- NADH-DH and NDH-F polypeptidee0
- Direction
- higher ratee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“NADH-DH and NDH-F polypeptide rapidly increased up to 16 h in PhL, GL+ H2O2, and, at higher rate, in PhL and paraquat”
t0“Barley”
Claim · model-written summary
The increases of NADH-DH and NDH-F after 4 h in photooxidative light and GL + H2O2 were not accompanied by significant changes in ndhB and ndhF transcripts.
- Taxon
- BarleyHordeum vulgaret0
- Treatment
- PhL and GL + H2O2e0
- Gene
- ndhB and ndhFe0
- Outcome
- ndhB and ndhF transcriptse0
- Direction
- not accompanied by significant changese0
- Qualifier
- after 4 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The observed increases of NADH-DH and NDH-F after 4 h in PhL and GL + H2O2 were not accompanied by significant changes in ndhB and ndhF transcripts”
t0“Barley”
Claim · model-written summary
At 16-h incubations the changes in NADH-DH and NDH-F closely correlated with higher ndhB and ndhF transcript levels.
- Taxon
- BarleyHordeum vulgaret0
- Gene
- ndhB and ndhFe0
- Outcome
- NADH-DH and NDH-F changese0
- Direction
- highere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at 16-h incubations NADH-DH and NDH-F changes closely correlated with higher ndhB and ndhF transcript levels”
t0“Barley”
Claim · model-written summary
All these effects were prevented by the H2O2 scavenger dimethylthiourea.
- Taxon
- BarleyHordeum vulgaret0
- Treatment
- dimethylthioureae0
- Outcome
- All these effectse0
- Direction
- preventede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All these effects were prevented by dimethylthiourea”
t0“Barley”
Claim · model-written summary
The authors propose that photooxidative induction of chloroplastic ndh genes is mediated by H2O2, through rapid translation of pre-existing transcripts and increased ndh transcript levels.
- Taxon
- BarleyHordeum vulgaret0
- Gene
- chloroplastic ndh genese0
- Compound
- H2O2e0
- Outcome
- induction of chloroplastic ndh genese0
- Qualifier
- rapid translation of pre-existing transcriptse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It is proposed that the induction of chloroplastic ndh genes under photooxidative stress is mediated by H2O2 through mechanisms that involve a rapid translation of pre-existing transcripts and the increase of the ndh transcript levels”
t0“Barley”
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