Abstract
The patterns of light activation of 4 chloroplastic enzymes were examined in mesophyll protoplasts of pea (Pisum sativum) in the absence or presence of oligomycin (inhibitor of oxidative phosphorylation) or antimycin A (inhibitor of cytochrome pathway) or salicylhydroxamic acid (SHAM, inhibitor of alternative pathway). The results were compared with those of DCMU (inhibitor of photosynthetic electron transport). The light activation of NADP glyceraldehyde-3-phosphate dehydrogenase (NADP-GAPDH), fructose-1,6-bisphosphatase (FBPase), phosphoribulokinase (PRK) (enzymes of the Calvin cycle) and NADP malate dehydrogenase (NADP-MDH) (reflects chloroplast redox state) was more pronounced at limiting CO2 (0.1 mM NaHCO3) than that at optimal CO2 (1.0 mM NaHCO3). SHAM decreased markedly (up to 33%) the light activation of all 4 enzymes, while antimycin A or oligomycin exerted only a limited effect (<10% decrease). Antimycin A or oligomycin or SHAM had no significant effect on light activation of these 4 enzymes in isolated chloroplasts. However, DCMU caused a remarkable decrease in light activation of enzymes in both protoplasts (up to 78%) and chloroplasts (up to 69%). These results suggest that the restriction of alternative pathway of mitochondrial metabolism results in a marked decrease in the light activation of key chloroplastic enzymes in mesophyll protoplasts but not in isolated chloroplasts. Such a decrease in the light activation of enzymes could be also a secondary feedback effect because of the restriction on carbon assimilation.
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Claims 11
Claim · model-written summary
Light activation of four chloroplastic enzymes was greater at limiting than optimal CO2.
- Taxon
- pea
Lathyrus oleraceust0 - Treatment
- limiting CO2 (0.1 mM NaHCO3)e0
- Gene
- NADP-GAPDHe0
- Outcome
- light activatione0
- Direction
- more pronouncede0
- Comparator
- optimal CO2 (1.0 mM NaHCO3)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The light activation of NADP glyceraldehyde-3-phosphate dehydrogenase (NADP-GAPDH), fructose-1,6-bisphosphatase (FBPase), phosphoribulokinase (PRK) (enzymes of the Calvin cycle) and NADP malate dehydrogenase (NADP-MDH) (reflects chloroplast redox state) was more pronounced at limiting CO2 (0.1 mM NaHCO3) than that at optimal CO2 (1.0 mM NaHCO3)”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
SHAM decreased light activation of all four enzymes by up to 33% in mesophyll protoplasts.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- SHAMe0
- Outcome
- light activation of all 4 enzymese0
- Direction
- decreasede0
- Value
- up to 33%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SHAM decreased markedly (up to 33%) the light activation of all 4 enzymes”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
Antimycin A caused less than 10% decrease in enzyme light activation in protoplasts.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- antimycin Ae0
- Outcome
- light activatione1
- Direction
- decreasee0
- Value
- <10%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“antimycin A or oligomycin exerted only a limited effect (<10% decrease)”
e1“The light activation of NADP glyceraldehyde-3-phosphate dehydrogenase”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
Oligomycin caused less than 10% decrease in enzyme light activation in protoplasts.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- oligomycine0
- Outcome
- light activatione1
- Direction
- decreasee0
- Value
- <10%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“antimycin A or oligomycin exerted only a limited effect (<10% decrease)”
e1“The light activation of NADP glyceraldehyde-3-phosphate dehydrogenase”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
Antimycin A had no significant effect on enzyme light activation in isolated chloroplasts.
- Taxon
- peaLathyrus oleraceust0
- Organ / stage
- isolated chloroplastse0
- Treatment
- Antimycin Ae0
- Outcome
- light activation of these 4 enzymese0
- Direction
- no significant effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Antimycin A or oligomycin or SHAM had no significant effect on light activation of these 4 enzymes in isolated chloroplasts”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
Oligomycin had no significant effect on enzyme light activation in isolated chloroplasts.
- Taxon
- peaLathyrus oleraceust0
- Organ / stage
- isolated chloroplastse0
- Treatment
- oligomycine0
- Outcome
- light activation of these 4 enzymese0
- Direction
- no significant effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Antimycin A or oligomycin or SHAM had no significant effect on light activation of these 4 enzymes in isolated chloroplasts”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
SHAM had no significant effect on enzyme light activation in isolated chloroplasts.
- Taxon
- peaLathyrus oleraceust0
- Organ / stage
- isolated chloroplastse0
- Treatment
- SHAMe0
- Outcome
- light activation of these 4 enzymese0
- Direction
- no significant effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Antimycin A or oligomycin or SHAM had no significant effect on light activation of these 4 enzymes in isolated chloroplasts”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
DCMU reduced light activation of enzymes in protoplasts by up to 78%.
- Taxon
- peaLathyrus oleraceust0
- Organ / stage
- protoplastse0
- Treatment
- DCMUe0
- Outcome
- light activation of enzymese0
- Direction
- decreasee0
- Value
- up to 78%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DCMU caused a remarkable decrease in light activation of enzymes in both protoplasts (up to 78%) and chloroplasts (up to 69%)”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
DCMU reduced light activation of enzymes in chloroplasts by up to 69%.
- Taxon
- peaLathyrus oleraceust0
- Organ / stage
- chloroplastse0
- Treatment
- DCMUe0
- Outcome
- light activation of enzymese0
- Direction
- decreasee0
- Value
- up to 69%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DCMU caused a remarkable decrease in light activation of enzymes in both protoplasts (up to 78%) and chloroplasts (up to 69%)”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
Authors suggest that restricting mitochondrial alternative pathway reduces enzyme light activation in mesophyll protoplasts, but not isolated chloroplasts.
- Taxon
- peaLathyrus oleraceust0
- Outcome
- light activation of key chloroplastic enzymese0
- Direction
- decreasee0
- Qualifier
- restriction of alternative pathway of mitochondrial metabolisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These results suggest that the restriction of alternative pathway of mitochondrial metabolism results in a marked decrease in the light activation of key chloroplastic enzymes in mesophyll protoplasts but not in isolated chloroplasts”
t0“of pea (Pisum sativum) in the absence”
Claim · model-written summary
Authors suggest decreased enzyme activation could be secondary feedback from restricted carbon assimilation.
- Taxon
- peaLathyrus oleraceust0
- Outcome
- light activation of enzymese0
- Qualifier
- restriction on carbon assimilatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Such a decrease in the light activation of enzymes could be also a secondary feedback effect because of the restriction on carbon assimilation”
t0“of pea (Pisum sativum) in the absence”