Abstract
Field-emission scanning electron microscopy was used to measure wall thicknesses of different cell types in freeze-fractured hypocotyls of Arabidopsis thaliana. Measurements of uronic acid content, wall mass, and wall volume suggest that cell wall biosynthesis in this organ does not always keep pace with, and is not always tightly coupled to, elongation. In light-grown hypocotyls, walls thicken, maintain a constant thickness, or become thinner during elongation, depending upon the cell type and the stage of growth. In light-grown hypocotyls, exogenous gibberellic acid represses the extent of thickening and promotes cell elongation by both wall thinning and increased anisotropy during the early stages of hypocotyl elongation, and by increased wall deposition in the latter stages. Dark-grown hypocotyls, in the 48 h period between cold imbibition and seedling emergence, deposit very thick walls that subsequently thin in a narrow developmental window as the hypocotyl rapidly elongates. The rate of wall deposition is then maintained and keeps pace with cell elongation. The outer epidermal wall is always the thickest ( approximately 1 mum) whereas the thinnest walls, about 50 nm, are found in inner cell layers. It is concluded that control of wall thickness in different cell types is tightly regulated during hypocotyl development, and that wall deposition and cell elongation are not invariably coupled.
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Claims 10
Claim · model-written summary
Cell wall biosynthesis is not always coupled to hypocotyl elongation.
- Taxon
- Arabidopsis
Arabidopsist0 - Organ / stage
- hypocotylst0
- Outcome
- cell wall biosynthesise0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cell wall biosynthesis in this organ does not always keep pace with, and is not always tightly coupled to, elongation”
t0“Arabidopsis hypocotyls”
Claim · model-written summary
In light-grown hypocotyls, wall thickness can increase, remain constant, or decrease during elongation depending on cell type and stage.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- light-grown hypocotylse0
- Outcome
- walls thicken, maintain a constant thickness, or become thinnere0
- Qualifier
- depending upon the cell type and the stage of growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In light-grown hypocotyls, walls thicken, maintain a constant thickness, or become thinner during elongation, depending upon the cell type and the stage of growth”
t0“Arabidopsis hypocotyls”
Claim · model-written summary
Exogenous gibberellic acid represses early hypocotyl wall thickening.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- early stages of hypocotyl elongatione0
- Treatment
- exogenous gibberellic acide0
- Outcome
- extent of thickeninge0
- Direction
- repressese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenous gibberellic acid represses the extent of thickening and promotes cell elongation by both wall thinning and increased anisotropy during the early stages of hypocotyl elongation”
t0“Arabidopsis hypocotyls”
Claim · model-written summary
Exogenous gibberellic acid promotes early hypocotyl elongation with wall thinning and increased anisotropy.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- exogenous gibberellic acide0
- Outcome
- cell elongatione0
- Direction
- promotese0
- Qualifier
- wall thinning and increased anisotropye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exogenous gibberellic acid represses the extent of thickening and promotes cell elongation by both wall thinning and increased anisotropy during the early stages of hypocotyl elongation”
t0“Arabidopsis hypocotyls”
Claim · model-written summary
In later stages gibberellic acid promotes elongation by increased wall deposition.
- Taxon
- ArabidopsisArabidopsist0
- Treatment
- exogenous gibberellic acide1
- Outcome
- cell elongatione1
- Qualifier
- increased wall deposition in the latter stagese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“by increased wall deposition in the latter stages”
e1“exogenous gibberellic acid represses the extent of thickening and promotes cell elongation”
t0“Arabidopsis hypocotyls”
Claim · model-written summary
Dark-grown hypocotyls deposit very thick walls before seedling emergence.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- Dark-grown hypocotylse0
- Outcome
- deposit very thick wallse0
- Qualifier
- in the 48 h period between cold imbibition and seedling emergencee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Dark-grown hypocotyls, in the 48 h period between cold imbibition and seedling emergence, deposit very thick walls”
t0“Arabidopsis hypocotyls”
Claim · model-written summary
Dark-grown hypocotyl walls subsequently thin during rapid elongation.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- walls that subsequently thine0
- Qualifier
- in a narrow developmental window as the hypocotyl rapidly elongatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“walls that subsequently thin in a narrow developmental window as the hypocotyl rapidly elongates”
t0“Arabidopsis hypocotyls”
Claim · model-written summary
Wall deposition then keeps pace with cell elongation.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- hypocotylst0
- Outcome
- rate of wall depositione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate of wall deposition is then maintained and keeps pace with cell elongation”
t0“Arabidopsis hypocotyls”
Claim · model-written summary
The outer epidermal wall is the thickest at approximately 1 mum.
- Taxon
- ArabidopsisArabidopsist0
- Outcome
- outer epidermal walle0
- Value
- approximately 1 mume0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The outer epidermal wall is always the thickest ( approximately 1 mum)”
t0“Arabidopsis hypocotyls”
Claim · model-written summary
The thinnest walls occur in inner cell layers at about 50 nm.
- Taxon
- ArabidopsisArabidopsist0
- Organ / stage
- inner cell layerse0
- Outcome
- thinnest wallse0
- Value
- about 50 nme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the thinnest walls, about 50 nm, are found in inner cell layers”
t0“Arabidopsis hypocotyls”
The same questions in other papers
Gibberellic acid · cytology · ArabidopsisPositive and negative results
1 in the opposite direction
- no effect
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.