Abstract
The aim of this work was to study the role of the cell wall protein expansin in elongation growth. Expansins increase cell wall extensibility in vitro and are thought to be involved in cell elongation. Here, we studied the regulation of two tomato (Lycopersicon esculentum cv Moneymaker) expansin genes, LeExp2 and LeExp18, in rapidly expanding tissues. LeExp2 was strongly expressed in the elongation zone of hypocotyls and in the faster growing stem part during gravitropic stimulation. LeExp18 expression did not correlate with elongation growth. Exogenous application of hormones showed a substantial auxin-stimulation of LeExp2 mRNA in etiolated hypocotyls and a weaker auxin-stimulation of LeExp18 mRNA in stem tissue. Analysis of transcript accumulation revealed higher levels of LeExp2 and LeExp18 in light-treated, slow-growing tissue than in dark-treated, rapidly elongating tissue. Expansin protein levels and cell wall extension activities were similar in light- and dark-grown hypocotyl extracts. The results show a strong correlation between expansin gene expression and growth rate, but this correlation is not absolute. We conclude that elongation growth is likely to be controlled by expansin acting in concert with other factors that may limit growth under some physiological conditions.
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Claims 9
Claim · model-written summary
LeExp2 was strongly expressed in the hypocotyl elongation zone and faster-growing stem during gravitropic stimulation.
- Taxon
- tomato
Solanum lycopersicumt0 - Organ / stage
- hypocotylse0
- Gene
- LeExp2e0
- Outcome
- strongly expressede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“LeExp2 was strongly expressed in the elongation zone of hypocotyls and in the faster growing stem part during gravitropic stimulation.”
t0“tomato (Lycopersicon esculentum cv Moneymaker)”
Claim · model-written summary
LeExp18 expression did not correlate with elongation growth.
- Taxon
- tomatoSolanum lycopersicumt0
- Gene
- LeExp18e0
- Outcome
- elongation growthe0
- Direction
- did not correlatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“LeExp18 expression did not correlate with elongation growth.”
t0“tomato (Lycopersicon esculentum cv Moneymaker)”
Claim · model-written summary
Auxin substantially stimulated LeExp2 mRNA in etiolated hypocotyls.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- auxine0
- Gene
- LeExp2e0
- Outcome
- LeExp2 mRNAe0
- Direction
- stimulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a substantial auxin-stimulation of LeExp2 mRNA in etiolated hypocotyls”
t0“tomato (Lycopersicon esculentum cv Moneymaker)”
Claim · model-written summary
Auxin weakly stimulated LeExp18 mRNA in stem tissue.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- auxine0
- Gene
- LeExp18e0
- Outcome
- LeExp18 mRNAe0
- Direction
- stimulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a weaker auxin-stimulation of LeExp18 mRNA in stem tissue”
t0“tomato (Lycopersicon esculentum cv Moneymaker)”
Claim · model-written summary
LeExp2 transcript accumulation was higher in light-treated slow-growing tissue than in dark-treated rapidly elongating tissue.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- light-treatede0
- Outcome
- LeExp2e0
- Direction
- highere0
- Comparator
- dark-treatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher levels of LeExp2 and LeExp18 in light-treated, slow-growing tissue than in dark-treated, rapidly elongating tissue”
t0“tomato (Lycopersicon esculentum cv Moneymaker)”
Claim · model-written summary
LeExp18 transcript accumulation was higher in light-treated slow-growing tissue than in dark-treated rapidly elongating tissue.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- light-treatede0
- Outcome
- LeExp18e0
- Direction
- highere0
- Comparator
- dark-treatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“higher levels of LeExp2 and LeExp18 in light-treated, slow-growing tissue than in dark-treated, rapidly elongating tissue”
t0“tomato (Lycopersicon esculentum cv Moneymaker)”
Claim · model-written summary
Expansin protein levels were similar between light- and dark-grown hypocotyls.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- light-e0
- Outcome
- Expansin protein levelse0
- Direction
- similare0
- Comparator
- dark-growne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Expansin protein levels and cell wall extension activities were similar in light- and dark-grown hypocotyl extracts.”
t0“tomato (Lycopersicon esculentum cv Moneymaker)”
Claim · model-written summary
Cell wall extension activities were similar between light- and dark-grown hypocotyls.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- light-e0
- Outcome
- cell wall extension activitiese0
- Direction
- similare0
- Comparator
- dark-growne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Expansin protein levels and cell wall extension activities were similar in light- and dark-grown hypocotyl extracts.”
t0“tomato (Lycopersicon esculentum cv Moneymaker)”
Claim · model-written summary
The authors infer that expansin acts with other factors to control elongation growth.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- elongation growthe0
- Qualifier
- expansin acting in concert with other factorse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elongation growth is likely to be controlled by expansin acting in concert with other factors that may limit growth under some physiological conditions.”
t0“tomato (Lycopersicon esculentum cv Moneymaker)”
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