Abstract
Haploid callus cells of tobacco (Nicotiana tabacum) were grown photoautotrophically on a solid agar medium in the absence of sucrose in Petri plates in an atmosphere of 1% or 3% CO(2) in air. The averages of dry weight increases for four to five consecutive passages were 2.3- to 3.6-fold per 3-week passage for different subclones. Photosynthetic (14)CO(2) assimilation was maximum at about 1% CO(2) with half-maximal rates obtained at 0.2% CO(2). At saturating CO(2) concentration the average rate of CO(2) fixation was about 5 mumole per gram fresh weight per hour or about 125 mumole per mg of chlorophyll per hour.The existence of an active photorespiratory system in these tissues was established in a number of independent ways. The photosynthetic rate in 0.18% CO(2) was inhibited 38 to 50% in 100% O(2) compared with 21% O(2). Glycolate accumulated at a constant rate in the presence of 5 mm alpha-hydroxy-2-pyridinemethanesulfonic acid for 20 minutes in light. This rate was rapid relative to the photosynthetic rate. Glycolate synthesis was three times faster in autotrophic than in heterotrophic cells. [1-(14)C]Glycolate was rapidly metabolized and the products included (14)CO(2), [(14)C]glycine, and [(14)C]serine, thus demonstrating an active glycolate pathway. Photorespiration was demonstrated directly by measurement of an O(2)-dependent release of (14)CO(2) in the light from callus that fixed (14)CO(2) for about 22 hours. Autotrophic growth in 60% O(2) and 0.03% CO(2) was slowed and ceased entirely after two or three passages, while heterotrophic growth was unaffected by 60% O(2) in the atmosphere.The method of growing autotrophic callus which has an active photorespiratory system should facilitate the selection and analysis of photosynthetic mutants in which photorespiration is regulated.
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Claims 10
Claim · model-written summary
Autotrophic tobacco callus dry weight increased 2.3- to 3.6-fold per three-week passage.
- Taxon
- tobacco (Nicotiana tabacum)
Nicotiana tabacume1 - Outcome
- dry weight increasese0
- Value
- 2.3- to 3.6-fold per 3-week passagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The averages of dry weight increases for four to five consecutive passages were 2.3- to 3.6-fold per 3-week passage for different subclones”
e1“callus cells of tobacco (Nicotiana tabacum)”
Claim · model-written summary
Photosynthetic carbon assimilation peaked near 1% CO(2), with half-maximal rates at 0.2%.
- Taxon
- tobacco (Nicotiana tabacum)Nicotiana tabacume1
- Outcome
- Photosynthetic (14)CO(2) assimilatione0
- Direction
- maximume0
- Value
- about 1% CO(2)e0
- Qualifier
- 0.2% CO(2)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthetic (14)CO(2) assimilation was maximum at about 1% CO(2) with half-maximal rates obtained at 0.2% CO(2)”
e1“callus cells of tobacco (Nicotiana tabacum)”
Claim · model-written summary
At saturating CO(2), fixation averaged about 5 mumole per gram fresh weight per hour.
- Taxon
- tobacco (Nicotiana tabacum)Nicotiana tabacume1
- Outcome
- rate of CO(2) fixatione0
- Value
- about 5 mumole per gram fresh weight per houre0
- Qualifier
- about 125 mumole per mg of chlorophyll per houre0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At saturating CO(2) concentration the average rate of CO(2) fixation was about 5 mumole per gram fresh weight per hour or about 125 mumole per mg of chlorophyll per hour”
e1“callus cells of tobacco (Nicotiana tabacum)”
Claim · model-written summary
At 0.18% CO(2), 100% O(2) inhibited photosynthesis 38 to 50% relative to 21% O(2).
- Taxon
- tobacco (Nicotiana tabacum)Nicotiana tabacume1
- Treatment
- 100% O(2)e0
- Outcome
- photosynthetic ratee0
- Direction
- inhibitede0
- Value
- 38 to 50%e0
- Qualifier
- 0.18% CO(2)e0
- Comparator
- 21% O(2)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The photosynthetic rate in 0.18% CO(2) was inhibited 38 to 50% in 100% O(2) compared with 21% O(2)”
e1“callus cells of tobacco (Nicotiana tabacum)”
Claim · model-written summary
Glycolate accumulated at a constant rate during light exposure with inhibitor present.
- Taxon
- tobacco (Nicotiana tabacum)Nicotiana tabacume1
- Treatment
- 5 mm alpha-hydroxy-2-pyridinemethanesulfonic acide0
- Outcome
- Glycolate accumulatede0
- Direction
- at a constant ratee0
- Qualifier
- for 20 minutes in lighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Glycolate accumulated at a constant rate in the presence of 5 mm alpha-hydroxy-2-pyridinemethanesulfonic acid for 20 minutes in light”
e1“callus cells of tobacco (Nicotiana tabacum)”
Claim · model-written summary
Autotrophic cells synthesized glycolate three times faster than heterotrophic cells.
- Taxon
- tobacco (Nicotiana tabacum)Nicotiana tabacume1
- Outcome
- Glycolate synthesise0
- Direction
- fastere0
- Value
- three timese0
- Comparator
- heterotrophic cellse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Glycolate synthesis was three times faster in autotrophic than in heterotrophic cells”
e1“callus cells of tobacco (Nicotiana tabacum)”
Claim · model-written summary
Labeled glycolate was rapidly metabolized to carbon dioxide, glycine and serine.
- Taxon
- tobacco (Nicotiana tabacum)Nicotiana tabacume1
- Outcome
- products included (14)CO(2), [(14)C]glycine, and [(14)C]serinee0
- Direction
- rapidly metabolizede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“[1-(14)C]Glycolate was rapidly metabolized and the products included (14)CO(2), [(14)C]glycine, and [(14)C]serine”
e1“callus cells of tobacco (Nicotiana tabacum)”
Claim · model-written summary
Oxygen-dependent labeled carbon dioxide release directly demonstrated photorespiration.
- Taxon
- tobacco (Nicotiana tabacum)Nicotiana tabacume1
- Outcome
- O(2)-dependent release of (14)CO(2)e0
- Qualifier
- about 22 hourse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photorespiration was demonstrated directly by measurement of an O(2)-dependent release of (14)CO(2) in the light from callus that fixed (14)CO(2) for about 22 hours”
e1“callus cells of tobacco (Nicotiana tabacum)”
Claim · model-written summary
Autotrophic growth under 60% O(2) and 0.03% CO(2) slowed and ceased after two or three passages.
- Taxon
- tobacco (Nicotiana tabacum)Nicotiana tabacume1
- Treatment
- 60% O(2) and 0.03% CO(2)e0
- Outcome
- Autotrophic growthe0
- Direction
- slowed and ceased entirelye0
- Qualifier
- after two or three passagese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Autotrophic growth in 60% O(2) and 0.03% CO(2) was slowed and ceased entirely after two or three passages”
e1“callus cells of tobacco (Nicotiana tabacum)”
Claim · model-written summary
Heterotrophic growth was unaffected by 60% atmospheric O(2).
- Taxon
- tobacco (Nicotiana tabacum)Nicotiana tabacume1
- Treatment
- 60% O(2) in the atmospheree0
- Outcome
- heterotrophic growthe0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“heterotrophic growth was unaffected by 60% O(2) in the atmosphere”
e1“callus cells of tobacco (Nicotiana tabacum)”
The same questions in other papers
co2 · growth · Nicotiana tabacum (tobacco)Positive and negative results
5 papers in the same direction as this paper · 12 in the opposite direction
- positive
- positive
- positive
14 papers more in this group
See all 18 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.