Abstract
Chloroplast replication has been studied in discs cut from the base of young spinach leaves and cultured on sterile nutrient agar. In discs grown in a growth cabinet chloroplast numbers per cell increased logarithmically with time over a 7-day culture period. Chloroplast replication proceeds in a similar way in cultured discs and in intact leaves. Cytokinins do not affect chloroplast replication in this system but they stimulate the fresh-weight growth of discs. Chloroplast replication is temperature dependent, having an optimum at 25 °C. By contrast chloroplast size is at a maximum in discs cultured at 12 °C. Light stimulates chloroplast replication, a linear relationship occurring between chloroplast number per cell and the daily quantity of light given to discs up to a saturating value of 250 J d−1. Daylength does not affect chloroplast formation in spinach. In a number of experiments a general relationship was established between chloroplast number per cell and cell size but no evidence is available to suggest that this correlation is causal. The results of experiments in which discs were transferred from dark to light suggest that some of the events which precede chloroplast replication may occur at similar rates in both light and dark.
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Claims 11
Claim · model-written summary
Chloroplast number per cell increased logarithmically over seven days.
- Taxon
- Spinach
Spinacia oleraceat0 - Organ / stage
- chloroplaste0
- Outcome
- chloroplast numbers per celle0
- Direction
- increasede0
- Value
- 7-day culture periode0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“chloroplast numbers per cell increased logarithmically with time over a 7-day culture period.”
t0“Spinach”
Claim · model-written summary
Replication proceeded similarly in cultured discs and intact leaves.
- Taxon
- SpinachSpinacia oleraceat0
- Organ / stage
- Chloroplaste0
- Outcome
- Chloroplast replicatione0
- Direction
- similar waye0
- Comparator
- intact leavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chloroplast replication proceeds in a similar way in cultured discs and in intact leaves.”
t0“Spinach”
Claim · model-written summary
Cytokinins did not affect chloroplast replication.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- Cytokininse0
- Outcome
- chloroplast replicatione0
- Direction
- do not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cytokinins do not affect chloroplast replication in this system”
t0“Spinach”
Claim · model-written summary
Cytokinins stimulated fresh-weight growth of discs.
- Taxon
- SpinachSpinacia oleraceat0
- Outcome
- fresh-weight growth of discse0
- Direction
- stimulatee0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“they stimulate the fresh-weight growth of discs.”
t0“Spinach”
Claim · model-written summary
Chloroplast replication was optimal at 25 °C.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- temperaturee0
- Outcome
- Chloroplast replicatione0
- Direction
- optimume0
- Value
- 25 °Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chloroplast replication is temperature dependent, having an optimum at 25 °C.”
t0“Spinach”
Claim · model-written summary
Chloroplast size was maximal at 12 °C.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- 12 °Ce0
- Outcome
- chloroplast sizee0
- Direction
- maximume0
- Value
- 12 °Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“chloroplast size is at a maximum in discs cultured at 12 °C.”
t0“Spinach”
Claim · model-written summary
Light stimulated chloroplast replication.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- Lighte0
- Outcome
- chloroplast replicatione0
- Direction
- stimulatese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Light stimulates chloroplast replication”
t0“Spinach”
Claim · model-written summary
Chloroplast number rose linearly with daily light to a saturation of 250 J d−1.
- Taxon
- SpinachSpinacia oleraceat0
- Treatment
- daily quantity of lighte0
- Outcome
- chloroplast number per celle0
- Direction
- increaseinferrede0
- Value
- 250 J d−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a linear relationship occurring between chloroplast number per cell and the daily quantity of light given to discs up to a saturating value of 250 J d−1.”
t0“Spinach”
Claim · model-written summary
Daylength did not affect chloroplast formation.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- Daylengthe0
- Outcome
- chloroplast formatione0
- Direction
- does not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Daylength does not affect chloroplast formation in spinach.”
Claim · model-written summary
Chloroplast number and cell size were generally related, without evidence of causality.
- Taxon
- SpinachSpinacia oleraceat0
- Organ / stage
- celle0
- Outcome
- chloroplast number per celle0
- Qualifier
- no evidence is available to suggest that this correlation is causale0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a general relationship was established between chloroplast number per cell and cell size but no evidence is available to suggest that this correlation is causal.”
t0“Spinach”
Claim · model-written summary
Events preceding replication may progress at similar rates in light and dark.
- Taxon
- SpinachSpinacia oleraceat0
- Outcome
- events which precede chloroplast replicatione0
- Direction
- similar ratese0
- Comparator
- light and darke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“some of the events which precede chloroplast replication may occur at similar rates in both light and dark.”
t0“Spinach”