Abstract
The hydrolysis of cell wall pectins by tomato (Lycopersicon esculentum) polygalacturonase (PG) in vitro is more extensive than the degradation affecting these polymers during ripening. We examined the hydrolysis of polygalacturonic acid and cell walls by PG isozyme 2 (PG2) under conditions widely adopted in the literature (pH 4.5 and containing Na+) and under conditions approximating the apoplastic environment of tomato fruit (pH 6.0 and K+ as the predominate cation). The pH optima for PG2 in the presence of K+ were 1.5 and 0.5 units higher for the hydrolysis of polygalacturonic acid and cell walls, respectively, compared with activity in the presence of Na+. Increasing K+ concentration stimulated pectin solubilization at pH 4.5 but had little influence at pH 6.0. Pectin depolymerization by PG2 was extensive at pH values from 4.0 to 5.0 and was further enhanced at high K+ levels. Oligomers were abundant products in in vitro reactions at pH 4.0 to 5.0, decreased sharply at pH 5.5, and were negligible at pH 6.0. EDTA stimulated PG-mediated pectin solubilization at pH 6.0 but did not promote oligomer production. Ca2+ suppressed PG-mediated pectin release at pH 4.5 yet had minimal influence on the proportional recovery of oligomers. Extensive pectin breakdown in processed tomato might be explained in part by cation- and low-pH-induced stimulation of PG and other wall-associated enzymes.
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Claims 14
Claim · model-written summary
PG2 pH optimum for polygalacturonic acid hydrolysis was 1.5 units higher with K+ than Na+.
- Taxon
- tomato
Solanum lycopersicume1 - Treatment
- K+e0
- Gene
- PG2e0
- Outcome
- pH optima for PG2e0
- Direction
- highere0
- Value
- 1.5e0
- Qualifier
- hydrolysis of polygalacturonic acide0
- Comparator
- Na+e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The pH optima for PG2 in the presence of K+ were 1.5 and 0.5 units higher for the hydrolysis of polygalacturonic acid and cell walls, respectively, compared with activity in the presence of Na+”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
PG2 pH optimum for cell wall hydrolysis was 0.5 units higher with K+ than Na+.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- K+e0
- Gene
- PG2e0
- Outcome
- pH optima for PG2e0
- Direction
- highere0
- Value
- 0.5e0
- Qualifier
- hydrolysis of polygalacturonic acid and cell wallse0
- Comparator
- Na+e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The pH optima for PG2 in the presence of K+ were 1.5 and 0.5 units higher for the hydrolysis of polygalacturonic acid and cell walls, respectively, compared with activity in the presence of Na+”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
Increasing K+ stimulated pectin solubilization at pH 4.5.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- Increasing K+ concentratione0
- Outcome
- pectin solubilizatione0
- Direction
- stimulatede0
- Qualifier
- pH 4.5e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing K+ concentration stimulated pectin solubilization at pH 4.5”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
Increasing K+ had little influence on pectin solubilization at pH 6.0.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- Increasing K+ concentratione0
- Outcome
- pectin solubilizatione0
- Direction
- little influencee0
- Qualifier
- pH 6.0e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing K+ concentration stimulated pectin solubilization at pH 4.5 but had little influence at pH 6.0”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
PG2 extensively depolymerized pectin from pH 4.0 to 5.0.
- Taxon
- tomatoSolanum lycopersicume1
- Gene
- PG2e0
- Outcome
- Pectin depolymerizatione0
- Direction
- extensivee0
- Qualifier
- pH values from 4.0 to 5.0e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pectin depolymerization by PG2 was extensive at pH values from 4.0 to 5.0”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
High K+ further enhanced pectin depolymerization.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- high K+ levelse0
- Gene
- PG2e0
- Outcome
- Pectin depolymerizatione0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pectin depolymerization by PG2 was extensive at pH values from 4.0 to 5.0 and was further enhanced at high K+ levels”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
Oligomers were abundant at pH 4.0 to 5.0.
- Taxon
- tomatoSolanum lycopersicume1
- Outcome
- Oligomerse0
- Direction
- abundante0
- Qualifier
- pH 4.0 to 5.0e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oligomers were abundant products in in vitro reactions at pH 4.0 to 5.0”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
Oligomers sharply decreased at pH 5.5.
- Taxon
- tomatoSolanum lycopersicume2
- Outcome
- Oligomerse1
- Direction
- decreased sharplye0
- Qualifier
- pH 5.5e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“decreased sharply at pH 5.5”
e1“Oligomers were abundant products”
e2“tomato (Lycopersicon esculentum)”
Claim · model-written summary
Oligomers were negligible at pH 6.0.
- Taxon
- tomatoSolanum lycopersicume2
- Outcome
- Oligomerse1
- Direction
- negligiblee0
- Qualifier
- pH 6.0e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were negligible at pH 6.0”
e1“Oligomers were abundant products”
e2“tomato (Lycopersicon esculentum)”
Claim · model-written summary
EDTA stimulated PG-mediated pectin solubilization at pH 6.0.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- EDTAe0
- Gene
- PGe0
- Outcome
- pectin solubilizatione0
- Direction
- stimulatede0
- Qualifier
- pH 6.0e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“EDTA stimulated PG-mediated pectin solubilization at pH 6.0”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
EDTA did not promote oligomer production.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- EDTAe0
- Outcome
- oligomer productione0
- Direction
- did not promotee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“EDTA stimulated PG-mediated pectin solubilization at pH 6.0 but did not promote oligomer production”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
Ca2+ suppressed PG-mediated pectin release at pH 4.5.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- Ca2+e0
- Outcome
- pectin releasee0
- Direction
- suppressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ca2+ suppressed PG-mediated pectin release at pH 4.5”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
Ca2+ had minimal influence on proportional oligomer recovery.
- Taxon
- tomatoSolanum lycopersicume1
- Treatment
- Ca2+e0
- Outcome
- proportional recovery of oligomerse0
- Direction
- minimal influencee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ca2+ suppressed PG-mediated pectin release at pH 4.5 yet had minimal influence on the proportional recovery of oligomers”
e1“tomato (Lycopersicon esculentum)”
Claim · model-written summary
The authors suggest that low pH and cations partly explain extensive pectin breakdown in processed tomato.
- Taxon
- tomatoSolanum lycopersicume0
- Outcome
- Extensive pectin breakdowne0
- Qualifier
- cation- and low-pH-induced stimulation of PG and other wall-associated enzymese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Extensive pectin breakdown in processed tomato might be explained in part by cation- and low-pH-induced stimulation of PG and other wall-associated enzymes”
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See all 10 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.