Abstract
The function of chloroplastic NAD(P)H dehydrogenase (NDH) was examined by comparing a tobacco transformant (DeltandhB) in which the ndhB gene had been disrupted with its wild type, upon exposure to chilling temperature (4 degrees C) under low irradiance (100 micro mol m(-2) s(-1) PFD). During the chilling stress, the maximum photochemical efficiency of PSII (F(v)/F(m)) decreased markedly in both the wild type and DeltandhB. However, both F(v)/F(m) and P700(+), as well as the PSII-driven electron transport rate (ETR), in DeltandhB were lower than that in the wild type, implying that NDH-dependent cyclic electron flow around PSI functioned to protect the photosynthetic apparatus from chilling stress under low irradiance. Under the stress, non-photochemical quenching (NPQ), particularly the fast relaxing NPQ component (qf) and the de-epoxidized ratio of the xanthophyll cycle pigments, (A+Z)/(V+A+Z), were distinguishable in DeltandhB from those in the wild type. The lower NPQ in DeltandhB might be related to an inefficient proton gradient across thylakoid membranes (DeltapH) because of lacking an NDH-dependent cyclic electron flow around PSI at chilling temperature under low irradiance.
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Claims 8
Claim · model-written summary
During chilling stress, the maximum photochemical efficiency of PSII decreased markedly in the tobacco wild type.
- Taxon
- tobacco
Nicotiana tabacume5 - Material
- the wild typee0
- Treatment
- chilling stresse0
- Outcome
- the maximum photochemical efficiency of PSII (F(v)/F(m))e0
- Direction
- decreased markedlye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“comparing a tobacco transformant (DeltandhB) in which the ndhB gene had been disrupted with its wild type”
e0“During the chilling stress, the maximum photochemical efficiency of PSII (F(v)/F(m)) decreased markedly in both the wild type and DeltandhB”
Claim · model-written summary
During chilling stress, the maximum photochemical efficiency of PSII decreased markedly in the DeltandhB tobacco transformant.
- Taxon
- tobaccoNicotiana tabacume5
- Material
- DeltandhBe0
- Treatment
- chilling stresse0
- Outcome
- the maximum photochemical efficiency of PSII (F(v)/F(m))e0
- Direction
- decreased markedlye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“comparing a tobacco transformant (DeltandhB) in which the ndhB gene had been disrupted with its wild type”
e0“During the chilling stress, the maximum photochemical efficiency of PSII (F(v)/F(m)) decreased markedly in both the wild type and DeltandhB”
Claim · model-written summary
The PSII-driven electron transport rate in DeltandhB was lower than in the wild type.
- Taxon
- tobaccoNicotiana tabacume5
- Material
- DeltandhBe1
- Outcome
- the PSII-driven electron transport rate (ETR)e1
- Direction
- were lowere1
- Comparator
- the wild typee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“comparing a tobacco transformant (DeltandhB) in which the ndhB gene had been disrupted with its wild type”
e1“However, both F(v)/F(m) and P700(+), as well as the PSII-driven electron transport rate (ETR), in DeltandhB were lower than that in the wild type”
Claim · model-written summary
F(v)/F(m) and P700(+) in DeltandhB were lower than in the wild type.
- Taxon
- tobaccoNicotiana tabacume5
- Material
- DeltandhBe1
- Outcome
- F(v)/F(m) and P700(+)e1
- Direction
- were lowere1
- Comparator
- the wild typee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“comparing a tobacco transformant (DeltandhB) in which the ndhB gene had been disrupted with its wild type”
e1“However, both F(v)/F(m) and P700(+), as well as the PSII-driven electron transport rate (ETR), in DeltandhB were lower than that in the wild type”
Claim · model-written summary
Under chilling and low irradiance, NPQ was lower in DeltandhB than in the wild type.
- Taxon
- tobaccoNicotiana tabacume5
- Material
- DeltandhBe3
- Outcome
- NPQe3
- Direction
- lowere3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“comparing a tobacco transformant (DeltandhB) in which the ndhB gene had been disrupted with its wild type”
e3“The lower NPQ in DeltandhB might be related to an inefficient proton gradient across thylakoid membranes”
Claim · model-written summary
The fast relaxing NPQ component (qf) and the de-epoxidized xanthophyll ratio were distinguishable between DeltandhB and the wild type under chilling.
- Taxon
- tobaccoNicotiana tabacume5
- Material
- DeltandhBe4
- Outcome
- the fast relaxing NPQ component (qf)e4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“comparing a tobacco transformant (DeltandhB) in which the ndhB gene had been disrupted with its wild type”
e4“particularly the fast relaxing NPQ component (qf) and the de-epoxidized ratio of the xanthophyll cycle pigments, (A+Z)/(V+A+Z), were distinguishable in DeltandhB from those in the wild type”
Claim · model-written summary
NDH-dependent cyclic electron flow around PSI is implied to protect the photosynthetic apparatus from chilling stress under low irradiance.
- Taxon
- tobaccoNicotiana tabacume5
- Outcome
- protect the photosynthetic apparatus from chilling stresse2
- Qualifier
- NDH-dependent cyclic electron flow around PSIe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“comparing a tobacco transformant (DeltandhB) in which the ndhB gene had been disrupted with its wild type”
e2“implying that NDH-dependent cyclic electron flow around PSI functioned to protect the photosynthetic apparatus from chilling stress under low irradiance”
Claim · model-written summary
The lower NPQ in DeltandhB may be related to an inefficient proton gradient across thylakoid membranes, because NDH-dependent cyclic electron flow is lacking.
- Taxon
- tobaccoNicotiana tabacume5
- Material
- DeltandhBe3
- Outcome
- NPQe3
- Qualifier
- an inefficient proton gradient across thylakoid membranese3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“comparing a tobacco transformant (DeltandhB) in which the ndhB gene had been disrupted with its wild type”
e3“The lower NPQ in DeltandhB might be related to an inefficient proton gradient across thylakoid membranes”
The same questions in other papers
cold · physiology: photosynthesis · Nicotiana tabacum (tobacco)Positive and negative results
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