Abstract
Much of the work on the distribution of 14C-labelled assimilates in tomato has been done in winter under low light intensities, and consequently the reported distribution patterns of 14C may not be representative of plants growing in high light. Further, there are several somewhat conflicting reports on patterns of distribution of 14C-assimilates in young tomato plants. We sought to clarify the situation by studying the distribution of 14C-assimilates in tomato plants of various ages grown in summer when the light intensity was high. In addition, the role of the stem as a storage organ for carbon was assessed by (a) identifying the chemical fractions in the stem internode below a fed leaf and monitoring 14 C activity in these fractions over a period of 49 d, and (b) measuring concentrations of unlabelled carbohydrates in the stem over the life of the plant. The patterns of distribution of 14C-assimilates we found for tomato grown under high light intensity confirmed some of those described for plants grown under low light, but export of 14C by fed leaves was generally higher than reported for much of the earlier work. Lower leaves of young plants exported over 50% of the 14C they fixed, although export fell sharply as the plants aged. Initially, the roots and apical tuft were strong sinks for assimilates, but they had declined in importance by the time plants reached the nine-leaf stage. On the other hand, the stem became progressively more important as a sink for 14C-assimilates. Older, lower leaves exported more of their 14C-assimilates to the upper part of the plant than to the roots, whereas young leaves near the top of the plant exported more of their assimilates to the roots. The stem internode immediately below a fed leaf had about twice the 14C activity of the internode above the leaf. Mature leaves above and below a fed leaf rarely imported much 14C, even when in the correct phyllotactic relationship to the fed leaf. In the first 3 d after feeding leaf 5 of nine-leaf plants, the organic and amino acid pools and the neutral fraction of the internode below the fed leaf had most of the 14C activity, but by 49 d after feeding, the ethanolic-insoluble, starch and lipid fractions had most of the 14C activity. Glucose, fructose and sucrose were the main sugars in the stem. Although concentrations of these sugars and starch declined in the stem as the plants matured, there was little evidence to indicate their use in fruit production. Stems of plants defoliated at the 44-leaf stage had lower concentrations of sugars and starch at maturity, and produced less fruit than the controls. It was concluded that tomato is sink rather than source limited with respect to carbon assimilates, and that the storage of carbon in the stem for a long period is possibly a residual perennial trait in tomato.Copyright 1994, 1999 Academic Press
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Claims 17
Claim · model-written summary
Tomato leaves generally exported more 14C under high light than earlier low-light reports.
- Taxon
- Tomato
Solanum lycopersicumt0 - Outcome
- export of 14Ce0
- Direction
- generally highere0
- Comparator
- earlier worke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“export of 14C by fed leaves was generally higher than reported for much of the earlier work”
t0“Tomato”
Claim · model-written summary
Lower leaves of young tomato plants exported over 50% of fixed 14C, and export fell sharply with age.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- Lower leaves of young plantse0
- Outcome
- 14C they fixede0
- Direction
- export fell sharplye0
- Value
- over 50%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Lower leaves of young plants exported over 50% of the 14C they fixed, although export fell sharply as the plants aged.”
t0“Tomato”
Claim · model-written summary
Roots and apical tuft were initially strong assimilate sinks but less important by the nine-leaf stage.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- roots and apical tufte0
- Outcome
- sinks for assimilatese0
- Direction
- declined in importancee0
- Qualifier
- nine-leaf stagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Initially, the roots and apical tuft were strong sinks for assimilates, but they had declined in importance by the time plants reached the nine-leaf stage.”
t0“Tomato”
Claim · model-written summary
The tomato stem became progressively more important as a sink for 14C assimilates.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- steme0
- Outcome
- sink for 14C-assimilatese0
- Direction
- progressively more importante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the stem became progressively more important as a sink for 14C-assimilates”
t0“Tomato”
Claim · model-written summary
Older lower leaves exported more 14C assimilates to upper plant parts than to roots.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- Older, lower leavese0
- Outcome
- 14C-assimilatese0
- Direction
- moree0
- Comparator
- rootse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Older, lower leaves exported more of their 14C-assimilates to the upper part of the plant than to the roots”
t0“Tomato”
Claim · model-written summary
Young upper leaves exported more assimilates to roots.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- young leaves near the top of the plante0
- Outcome
- assimilates to the rootse0
- Direction
- moree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“young leaves near the top of the plant exported more of their assimilates to the roots”
t0“Tomato”
Claim · model-written summary
The stem internode below a fed leaf had about twice the 14C activity of the internode above.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- stem internode immediately below a fed leafe0
- Outcome
- 14C activitye0
- Direction
- twicee0
- Value
- about twicee0
- Comparator
- internode above the leafe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The stem internode immediately below a fed leaf had about twice the 14C activity of the internode above the leaf”
t0“Tomato”
Claim · model-written summary
Mature leaves above and below a fed leaf rarely imported much 14C.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- Mature leaves above and below a fed leafe0
- Outcome
- imported much 14Ce0
- Direction
- rarelye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mature leaves above and below a fed leaf rarely imported much 14C”
t0“Tomato”
Claim · model-written summary
During the first three days, organic and amino acid pools and the neutral fraction contained most 14C activity in the internode below the fed leaf.
- Taxon
- TomatoSolanum lycopersicumt0
- Outcome
- 14C activitye0
- Direction
- moste0
- Qualifier
- first 3 d after feeding leaf 5 of nine-leaf plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the first 3 d after feeding leaf 5 of nine-leaf plants, the organic and amino acid pools and the neutral fraction of the internode below the fed leaf had most of the 14C activity”
t0“Tomato”
Claim · model-written summary
By 49 days, ethanolic-insoluble, starch and lipid fractions contained most 14C activity.
- Taxon
- TomatoSolanum lycopersicumt0
- Outcome
- 14C activitye0
- Direction
- moste0
- Qualifier
- 49 d after feedinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“by 49 d after feeding, the ethanolic-insoluble, starch and lipid fractions had most of the 14C activity”
t0“Tomato”
Claim · model-written summary
Glucose, fructose and sucrose were the main stem sugars.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- steme0
- Outcome
- Glucose, fructose and sucrosee0
- Direction
- maine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Glucose, fructose and sucrose were the main sugars in the stem”
t0“Tomato”
Claim · model-written summary
Stem concentrations of glucose, fructose, sucrose and starch declined as tomato plants matured.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- steme0
- Outcome
- concentrations of these sugars and starche0
- Direction
- declinede0
- Qualifier
- plants maturede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“concentrations of these sugars and starch declined in the stem as the plants matured”
e1“Glucose, fructose and sucrose were the main sugars in the stem”
t0“Tomato”
Claim · model-written summary
There was little evidence that stored stem sugars and starch were used for fruit production.
- Taxon
- TomatoSolanum lycopersicumt0
- Organ / stage
- steme1
- Outcome
- use in fruit productione0
- Direction
- little evidencee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was little evidence to indicate their use in fruit production”
e1“concentrations of these sugars and starch declined in the stem as the plants matured”
t0“Tomato”
Claim · model-written summary
Defoliation at the 44-leaf stage reduced mature stem sugar and starch concentrations.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- defoliated at the 44-leaf stagee0
- Outcome
- concentrations of sugars and starche0
- Direction
- lowere0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stems of plants defoliated at the 44-leaf stage had lower concentrations of sugars and starch at maturity, and produced less fruit than the controls.”
t0“Tomato”
Claim · model-written summary
Defoliation at the 44-leaf stage reduced fruit production.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- defoliated at the 44-leaf stagee0
- Outcome
- fruite0
- Direction
- lesse0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stems of plants defoliated at the 44-leaf stage had lower concentrations of sugars and starch at maturity, and produced less fruit than the controls.”
t0“Tomato”
Claim · model-written summary
The authors concluded that tomato carbon assimilate production is limited by sinks.
- Taxon
- tomatoSolanum lycopersicume0
- Outcome
- carbon assimilatese0
- Qualifier
- sink rather than source limitede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“tomato is sink rather than source limited with respect to carbon assimilates”
Claim · model-written summary
The authors suggested long-term stem carbon storage may be a residual perennial trait in tomato.
- Taxon
- tomatoSolanum lycopersicume0
- Outcome
- storage of carbon in the steme0
- Qualifier
- possibly a residual perennial traite0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the storage of carbon in the stem for a long period is possibly a residual perennial trait in tomato”
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