Abstract
Folate deficiency leads to neural tube defects and other human diseases, and is a global health problem. Because plants are major folate sources for humans, we have sought to enhance plant folate levels (biofortification). Folates are synthesized from pteridine, p-aminobenzoate (PABA), and glutamate precursors. Previously, we increased pteridine production in tomato fruit up to 140-fold by overexpressing GTP cyclohydrolase I, the first enzyme of pteridine synthesis. This strategy increased folate levels 2-fold, but engineered fruit were PABA-depleted. We report here the engineering of fruit-specific overexpression of aminodeoxychorismate synthase, which catalyzes the first step of PABA synthesis. The resulting fruit contained an average of 19-fold more PABA than controls. When transgenic PABA- and pteridine-overproduction traits were combined by crossing, vine-ripened fruit accumulated up to 25-fold more folate than controls. Folate accumulation was almost as high (up to 15-fold) in fruit harvested green and ripened by ethylene-gassing, as occurs in commerce. The accumulated folates showed normal proportions of one-carbon forms, with 5-methyltetrahydrofolate the most abundant, but were less extensively polyglutamylated than controls. Folate concentrations in developing fruit did not change in controls, but increased continuously throughout ripening in transgenic fruit. Pteridine and PABA levels in transgenic fruit were >20-fold higher than in controls, but the pathway intermediates dihydropteroate and dihydrofolate did not accumulate, pointing to a flux constraint at the dihydropteroate synthesis step. The folate levels we achieved provide the complete adult daily requirement in less than one standard serving.
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Claims 15
Claim · model-written summary
Earlier GTP cyclohydrolase I overexpression raised pteridine up to 140-fold.
- Taxon
- tomato
Solanum lycopersicume0 - Treatment
- overexpressing GTP cyclohydrolase Ie0
- Gene
- GTP cyclohydrolase Ie0
- Outcome
- pteridine productione0
- Direction
- increasede0
- Value
- 140-folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Previously, we increased pteridine production in tomato fruit up to 140-fold by overexpressing GTP cyclohydrolase I”
Claim · model-written summary
The earlier strategy doubled folate levels.
- Taxon
- tomatoSolanum lycopersicumt0
- Treatment
- This strategye0
- Outcome
- folate levelse0
- Direction
- increasede0
- Value
- 2-folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This strategy increased folate levels 2-fold, but engineered fruit were PABA-depleted.”
t0“tomato”
Claim · model-written summary
Earlier engineered fruit were depleted of PABA.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- PABA-depletede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“engineered fruit were PABA-depleted”
t0“tomato”
Claim · model-written summary
Aminodeoxychorismate synthase overexpression raised fruit PABA 19-fold against controls.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- fruite0
- Treatment
- fruit-specific overexpression of aminodeoxychorismate synthasee1
- Outcome
- PABAe0
- Direction
- moree0
- Value
- 19-folde0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The resulting fruit contained an average of 19-fold more PABA than controls.”
e1“fruit-specific overexpression of aminodeoxychorismate synthase”
t0“tomato”
Claim · model-written summary
Crossing PABA and pteridine overproducers gave up to 25-fold more folate in vine-ripened fruit.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- vine-ripened fruite0
- Treatment
- transgenic PABA- and pteridine-overproduction traits were combined by crossinge0
- Outcome
- folatee0
- Direction
- moree0
- Value
- 25-folde0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When transgenic PABA- and pteridine-overproduction traits were combined by crossing, vine-ripened fruit accumulated up to 25-fold more folate than controls.”
t0“tomato”
Claim · model-written summary
Green-harvested ethylene-ripened fruit accumulated up to 15-fold more folate.
- Taxon
- tomatoSolanum lycopersicumt0
- Organ / stage
- fruite0
- Treatment
- harvested green and ripened by ethylene-gassinge0
- Outcome
- Folate accumulatione0
- Direction
- highe0
- Value
- 15-folde0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Folate accumulation was almost as high (up to 15-fold) in fruit harvested green and ripened by ethylene-gassing, as occurs in commerce.”
t0“tomato”
Claim · model-written summary
Accumulated folates retained normal proportions of one-carbon forms, with 5-methyltetrahydrofolate most abundant.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- normal proportions of one-carbon formse0
- Qualifier
- 5-methyltetrahydrofolate the most abundante0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The accumulated folates showed normal proportions of one-carbon forms, with 5-methyltetrahydrofolate the most abundant, but were less extensively polyglutamylated than controls.”
t0“tomato”
Claim · model-written summary
Transgenic fruit folates were less polyglutamylated than controls.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- polyglutamylatede0
- Direction
- lesse0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The accumulated folates showed normal proportions of one-carbon forms, with 5-methyltetrahydrofolate the most abundant, but were less extensively polyglutamylated than controls.”
t0“tomato”
Claim · model-written summary
Control fruit folate concentrations did not change during development.
- Taxon
- tomatoSolanum lycopersicumt0
- Material
- controlse0
- Organ / stage
- developing fruite0
- Outcome
- Folate concentrationse0
- Direction
- did not changee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Folate concentrations in developing fruit did not change in controls, but increased continuously throughout ripening in transgenic fruit.”
t0“tomato”
Claim · model-written summary
Transgenic fruit folate concentrations increased throughout ripening.
- Taxon
- tomatoSolanum lycopersicumt0
- Material
- transgenic fruite0
- Organ / stage
- ripeninge0
- Outcome
- Folate concentrationse0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Folate concentrations in developing fruit did not change in controls, but increased continuously throughout ripening in transgenic fruit.”
t0“tomato”
Claim · model-written summary
Transgenic fruit pteridine levels exceeded controls by over 20-fold.
- Taxon
- tomatoSolanum lycopersicumt0
- Material
- transgenic fruite0
- Outcome
- Pteridinee0
- Direction
- highere0
- Value
- >20-folde0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pteridine and PABA levels in transgenic fruit were >20-fold higher than in controls, but the pathway intermediates dihydropteroate and dihydrofolate did not accumulate”
t0“tomato”
Claim · model-written summary
Transgenic fruit PABA levels exceeded controls by over 20-fold.
- Taxon
- tomatoSolanum lycopersicumt0
- Material
- transgenic fruite0
- Outcome
- PABA levelse0
- Direction
- highere0
- Value
- >20-folde0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pteridine and PABA levels in transgenic fruit were >20-fold higher than in controls, but the pathway intermediates dihydropteroate and dihydrofolate did not accumulate”
t0“tomato”
Claim · model-written summary
Dihydropteroate and dihydrofolate did not accumulate in transgenic fruit.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- dihydropteroate and dihydrofolate did not accumulatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the pathway intermediates dihydropteroate and dihydrofolate did not accumulate”
t0“tomato”
Claim · model-written summary
The authors infer a flux constraint at dihydropteroate synthesis.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- flux constrainte0
- Qualifier
- dihydropteroate synthesis stepe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pointing to a flux constraint at the dihydropteroate synthesis step”
t0“tomato”
Claim · model-written summary
The achieved fruit folate level supplies a complete adult daily requirement in less than one serving.
- Taxon
- tomatoSolanum lycopersicumt0
- Outcome
- complete adult daily requiremente0
- Value
- less than one standard servinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The folate levels we achieved provide the complete adult daily requirement in less than one standard serving.”
t0“tomato”
The same questions in other papers
transgenic · molecular: metabolites · Solanum lycopersicum (tomato)Positive and negative results
15 papers in the same direction as this paper · 9 in the opposite direction
- negative
- no effect
- negative
21 papers more in this group
See all 25 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.