Abstract
Pectin methylesterase (PME), a ubiquitous enzyme in plants, de-esterifies the methoxylated pectin in the plant cell wall. We have characterized a PME gene (designated as pmeu1) from tomato (Lycopersicon esculentum) with an expression that is higher in younger root, leaf, and fruit tissues than in older tissues. Hypocotyls and epicotyls show higher accumulation of pmeu1 transcripts compared with cotyledons. pmeu1 represents a single-copy gene in the tomato genome. Comparison of the deduced amino acid sequence of pmeu1 with other PME homologs showed that the N-terminal halves are highly variable, and the C-terminal halves are relatively conserved in plant PMEs. Constitutive expression of a fruit-specific PME antisense gene does not affect the level of pmeu1 transcripts in vegetative tissues but does lower the level of PMEU1 mRNA in developing tomato fruits. These results suggest that there exists developmentally regulated silencing of pmeu1 by a heterologous PME antisense gene. Expression of pmeu1 in tobacco (Nicotiana tabacum) under the control of the cauliflower mosaic virus 35S promoter caused up to a 4-fold increase in PME specific activity that was correlated with the accumulation of PMEU1 mRNA. In vitro transcription-translation analyses show that pmeu1 encodes a 64-kD polypeptide, whereas transgenic tobacco plants expressing pmeu1 accumulate a new 37-kD polypeptide, suggesting extensive posttranslational processing of PMEU1. These results are the first evidence, to our knowledge, of the functional characterization of a PME gene and the extensive modification of the encoded polypeptide.
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Claims 12
Claim · model-written summary
Tomato pmeu1 expression is higher in younger root, leaf and fruit tissues than older tissues.
- Taxon
- tomato
Solanum lycopersicume0 - Organ / stage
- younger root, leaf, and fruit tissuese0
- Gene
- pmeu1e0
- Outcome
- expressione0
- Direction
- highere0
- Comparator
- older tissuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We have characterized a PME gene (designated as pmeu1) from tomato (Lycopersicon esculentum) with an expression that is higher in younger root, leaf, and fruit tissues than in older tissues”
Claim · model-written summary
Hypocotyls and epicotyls accumulate more pmeu1 transcripts than cotyledons.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- Hypocotyls and epicotylse0
- Gene
- pmeu1e0
- Outcome
- accumulation of pmeu1 transcriptse0
- Direction
- highere0
- Comparator
- cotyledonse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hypocotyls and epicotyls show higher accumulation of pmeu1 transcripts compared with cotyledons.”
t0“Tomato Pectin Methylesterase”
Claim · model-written summary
pmeu1 is a single-copy gene in tomato.
- Taxon
- tomatoSolanum lycopersicume0
- Gene
- pmeu1e0
- Outcome
- single-copy genee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pmeu1 represents a single-copy gene in the tomato genome.”
Claim · model-written summary
The N-terminal halves of plant PME homologs are highly variable.
Verbatim
e0“the N-terminal halves are highly variable, and the C-terminal halves are relatively conserved in plant PMEs”
Claim · model-written summary
The C-terminal halves of plant PMEs are relatively conserved.
Verbatim
e0“the C-terminal halves are relatively conserved in plant PMEs”
Claim · model-written summary
Constitutive fruit-specific PME antisense expression does not affect pmeu1 transcripts in vegetative tissues.
- Taxon
- tomatoSolanum lycopersicume0
- Organ / stage
- vegetative tissuese0
- Treatment
- Constitutive expression of a fruit-specific PME antisense genee0
- Gene
- pmeu1e0
- Outcome
- level of pmeu1 transcriptse0
- Direction
- does not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Constitutive expression of a fruit-specific PME antisense gene does not affect the level of pmeu1 transcripts in vegetative tissues but does lower the level of PMEU1 mRNA in developing tomato fruits.”
t0“Tomato”
Claim · model-written summary
Constitutive fruit-specific PME antisense expression lowers PMEU1 mRNA in developing tomato fruits.
- Taxon
- tomatoSolanum lycopersicume0
- Organ / stage
- developing tomato fruitse0
- Treatment
- Constitutive expression of a fruit-specific PME antisense genee0
- Gene
- PMEU1e0
- Outcome
- level of PMEU1 mRNAe0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Constitutive expression of a fruit-specific PME antisense gene does not affect the level of pmeu1 transcripts in vegetative tissues but does lower the level of PMEU1 mRNA in developing tomato fruits.”
Claim · model-written summary
pmeu1 expressed in tobacco increased PME specific activity by up to fourfold, correlated with PMEU1 mRNA accumulation.
- Taxon
- tobacco
Nicotiana tabacume0 - Treatment
- Expression of pmeu1e0
- Gene
- pmeu1e0
- Outcome
- PME specific activitye0
- Direction
- increasee0
- Value
- 4-folde0
- Qualifier
- correlated with the accumulation of PMEU1 mRNAe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Expression of pmeu1 in tobacco (Nicotiana tabacum) under the control of the cauliflower mosaic virus 35S promoter caused up to a 4-fold increase in PME specific activity that was correlated with the accumulation of PMEU1 mRNA.”
Claim · model-written summary
In vitro transcription-translation showed pmeu1 encodes a 64-kD polypeptide.
- Taxon
- TomatoSolanum lycopersicumt0
- Gene
- pmeu1e0
- Outcome
- polypeptidee0
- Value
- 64-kDe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In vitro transcription-translation analyses show that pmeu1 encodes a 64-kD polypeptide”
t0“Tomato”
Claim · model-written summary
Transgenic tobacco expressing pmeu1 accumulated a new 37-kD polypeptide.
- Taxon
- tobaccoNicotiana tabacume0
- Gene
- pmeu1e0
- Outcome
- new 37-kD polypeptidee0
- Value
- 37-kDe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“transgenic tobacco plants expressing pmeu1 accumulate a new 37-kD polypeptide”
Claim · model-written summary
The difference between the encoded and accumulated polypeptides suggests extensive PMEU1 posttranslational processing.
- Taxon
- TomatoSolanum lycopersicumt0
- Gene
- PMEU1e0
- Outcome
- posttranslational processinge0
- Qualifier
- extensivee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggesting extensive posttranslational processing of PMEU1”
t0“Tomato”
Claim · model-written summary
The authors suggest developmental silencing of pmeu1 by a heterologous PME antisense gene.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- heterologous PME antisense genee0
- Gene
- pmeu1e0
- Outcome
- silencing of pmeu1e0
- Qualifier
- developmentally regulatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These results suggest that there exists developmentally regulated silencing of pmeu1 by a heterologous PME antisense gene.”
t0“Tomato”
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