Abstract
Epidemics of obesity and type 2 diabetes drive strong consumer interest in plant-based low-calorie sweeteners. Trilobatin is a sweetener found at high concentrations in the leaves of a range of crabapple (Malus) species, but not in domesticated apple (Malus × domestica) leaves, which contain trilobatin’s bitter positional isomer phloridzin. Variation in trilobatin content was mapped to the Trilobatin locus on LG 7 in a segregating population developed from a cross between domesticated apples and crabapples. Phloretin glycosyltransferase2 (PGT2) was identified by activity-directed protein purification and differential gene expression analysis in samples high in trilobatin but low in phloridzin. Markers developed for PGT2 cosegregated strictly with the Trilobatin locus. Biochemical analysis showed PGT2 efficiently catalyzed 4′-o-glycosylation of phloretin to trilobatin as well as 3-hydroxyphloretin to sieboldin. Transient expression of double bond reductase, chalcone synthase, and PGT2 genes reconstituted the apple pathway for trilobatin production in Nicotiana benthamiana. Transgenic M. × domestica plants overexpressing PGT2 produced high concentrations of trilobatin in young leaves. Transgenic plants were phenotypically normal, and no differences in disease susceptibility were observed compared to wild-type plants grown under simulated field conditions. Sensory analysis indicated that apple leaf teas from PGT2 transgenics were readily discriminated from control leaf teas and were perceived as significantly sweeter. Identification of PGT2 allows marker-aided selection to be developed to breed apples containing trilobatin, and for high amounts of this natural low-calorie sweetener to be produced via biopharming and metabolic engineering in yeast.
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Claims 13
Claim · model-written summary
Crabapple leaves contain high trilobatin, whereas domesticated apple leaves do not and contain phloridzin.
- Organ / stage
- leavese0
- Outcome
- Trilobatine0
- Direction
- high concentrationse0
- Comparator
- domesticated apple (Malus × domestica)e0
MalusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Trilobatin is a sweetener found at high concentrations in the leaves of a range of crabapple (Malus) species, but not in domesticated apple (Malus × domestica) leaves, which contain trilobatin’s bitter positional isomer phloridzin”
Claim · model-written summary
Variation in trilobatin content mapped to the Trilobatin locus on LG 7.
Not reportedDirection
Verbatim
e0“Variation in trilobatin content was mapped to the Trilobatin locus on LG 7 in a segregating population developed from a cross between domesticated apples and crabapples”
Claim · model-written summary
Activity purification and gene expression analysis identified PGT2 in samples high in trilobatin and low in phloridzin.
- Taxon
- apple
Malus domesticat0 - Gene
- Phloretin glycosyltransferase2 (PGT2)e0
- Outcome
- was identifiede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Phloretin glycosyltransferase2 (PGT2) was identified by activity-directed protein purification and differential gene expression analysis in samples high in trilobatin but low in phloridzin”
t0“domesticated apple (Malus × domestica) leaves”
Claim · model-written summary
PGT2 markers cosegregated with the Trilobatin locus.
- Taxon
- appleMalus domesticat0
- Gene
- PGT2e0
- Outcome
- cosegregated strictly with the Trilobatin locuse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Markers developed for PGT2 cosegregated strictly with the Trilobatin locus”
t0“domesticated apple (Malus × domestica) leaves”
Claim · model-written summary
PGT2 efficiently catalyzed phloretin glycosylation to trilobatin.
- Taxon
- appleMalus domesticat0
- Gene
- PGT2e0
- Outcome
- 4′-o-glycosylation of phloretin to trilobatine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PGT2 efficiently catalyzed 4′-o-glycosylation of phloretin to trilobatin as well as 3-hydroxyphloretin to sieboldin”
t0“domesticated apple (Malus × domestica) leaves”
Claim · model-written summary
PGT2 efficiently catalyzed conversion of 3-hydroxyphloretin to sieboldin.
- Taxon
- appleMalus domesticat0
- Gene
- PGT2e0
- Outcome
- 3-hydroxyphloretin to sieboldine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“PGT2 efficiently catalyzed 4′-o-glycosylation of phloretin to trilobatin as well as 3-hydroxyphloretin to sieboldin”
t0“domesticated apple (Malus × domestica) leaves”
Claim · model-written summary
Transient expression of three genes reconstituted the apple trilobatin pathway in Nicotiana benthamiana.
- Taxon
- Nicotiana benthamiana
Nicotiana benthamianae0 - Treatment
- Transient expression of double bond reductase, chalcone synthase, and PGT2 genese0
- Outcome
- apple pathway for trilobatin productione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transient expression of double bond reductase, chalcone synthase, and PGT2 genes reconstituted the apple pathway for trilobatin production in Nicotiana benthamiana”
Claim · model-written summary
PGT2 overexpressing domesticated apple produced high trilobatin concentrations in young leaves.
- Taxon
- M. × domesticaMalus domesticae0
- Organ / stage
- young leavese0
- Treatment
- overexpressing PGT2e0
- Gene
- PGT2e0
- Outcome
- trilobatine0
- Direction
- high concentrationse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transgenic M. × domestica plants overexpressing PGT2 produced high concentrations of trilobatin in young leaves”
Claim · model-written summary
PGT2 transgenic plants were phenotypically normal.
- Taxon
- appleMalus domesticat0
- Material
- Transgenic plantse0
- Outcome
- phenotypically normale0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transgenic plants were phenotypically normal”
t0“domesticated apple (Malus × domestica) leaves”
Claim · model-written summary
PGT2 transgenics had no observed disease susceptibility difference from wild type under simulated field conditions.
- Taxon
- appleMalus domesticat0
- Treatment
- PGT2 transgenicse1
- Outcome
- disease susceptibilitye0
- Direction
- no differencese0
- Comparator
- wild-type plantse0
- Setting
- simulated field conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no differences in disease susceptibility were observed compared to wild-type plants grown under simulated field conditions”
e1“apple leaf teas from PGT2 transgenics were readily discriminated from control leaf teas”
t0“domesticated apple (Malus × domestica) leaves”
Claim · model-written summary
Sensory assessors readily distinguished tea from PGT2 transgenic apple leaves from control tea.
- Taxon
- appleMalus domesticae0
- Material
- PGT2 transgenicse0
- Outcome
- readily discriminatede0
- Comparator
- control leaf tease0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“apple leaf teas from PGT2 transgenics were readily discriminated from control leaf teas”
Claim · model-written summary
Tea from PGT2 transgenic apple leaves was perceived as significantly sweeter than control tea.
- Taxon
- appleMalus domesticae0
- Material
- PGT2 transgenicse0
- Outcome
- sweetere0
- Direction
- sweetere0
- Comparator
- control leaf tease0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“apple leaf teas from PGT2 transgenics were readily discriminated from control leaf teas and were perceived as significantly sweeter”
Claim · model-written summary
Identification of PGT2 permits development of marker aided apple breeding for trilobatin.
- Taxon
- applesMalus domesticae0
- Gene
- PGT2e0
- Outcome
- marker-aided selection to be developed to breed apples containing trilobatine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Identification of PGT2 allows marker-aided selection to be developed to breed apples containing trilobatin”
The same questions in other papers
transgenic · yield · Nicotiana benthamianaResults agree
1 paper in the same direction as this paper
- positive
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.