Abstract
There are at least five lipoxygenases (TomloxA, TomloxB, TomloxC, TomloxD, and TomloxE) present in tomato (Lycopersicon esculentum Mill.) fruit, but their role in generation of fruit flavor volatiles has been unclear. To assess the physiological role of TomloxC in the generation of volatile C6 aldehyde and alcohol flavor compounds, we produced transgenic tomato plants with greatly reduced TomloxC using sense and antisense constructs under control of the cauliflower mosaic virus 35S promoter. The expression level of the TomloxC mRNA in some transgenic plants was selectively reduced by gene silencing or antisense inhibition to between 1% and 5% of the wild-type controls, but the expression levels of mRNAs for the four other isoforms were unaffected. The specific depletion of TomloxC in transgenic tomatoes led to a marked reduction in the levels of known flavor volatiles, including hexanal, hexenal, and hexenol, to as little as 1.5% of those of wild-type controls following maceration of ripening fruit. Addition of linoleic or linolenic acid to fruit homogenates significantly increased the levels of flavor volatiles, but the increase with the TomloxC-depleted transgenic fruit extracts was much lower than with the wild-type control. Confocal imaging of tobacco (Nicotiana tabacum) leaf cells expressing a TomloxC-GFP fusion confirmed a chloroplast localization of the protein. Together, these results suggest that TomloxC is a chloroplast-targeted lipoxygenase isoform that can use both linoleic and linolenic acids as substrates to generate volatile C6 flavor compounds. The roles of the other lipoxygenase isoforms are discussed.
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Claims 8
Claim · model-written summary
Some transgenic tomato plants had TomloxC mRNA at 1% to 5% of wild type.
- Taxon
- Tomato
Solanum lycopersicumt0 - Treatment
- gene silencing or antisense inhibitione0
- Gene
- TomloxCe0
- Outcome
- expression level of the TomloxC mRNAe0
- Direction
- reducede0
- Value
- between 1% and 5%e0
- Comparator
- wild-type controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The expression level of the TomloxC mRNA in some transgenic plants was selectively reduced by gene silencing or antisense inhibition to between 1% and 5% of the wild-type controls”
t0“Tomato”
Claim · model-written summary
Silencing TomloxC left the four other isoform mRNA levels unaffected.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- gene silencing or antisense inhibitione1
- Outcome
- expression levels of mRNAs for the four other isoformse0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“expression levels of mRNAs for the four other isoforms were unaffected”
e1“by gene silencing or antisense inhibition”
t0“Tomato”
Claim · model-written summary
TomloxC depletion reduced hexanal, hexenal, and hexenol to as little as 1.5% of wild-type levels after fruit maceration.
- Taxon
- tomatoesSolanum lycopersicume0
- Organ / stage
- ripening fruite0
- Treatment
- specific depletion of TomloxCe0
- Gene
- TomloxCe0
- Outcome
- hexanal, hexenal, and hexenole0
- Direction
- reductione0
- Value
- 1.5%e0
- Comparator
- wild-type controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The specific depletion of TomloxC in transgenic tomatoes led to a marked reduction in the levels of known flavor volatiles, including hexanal, hexenal, and hexenol, to as little as 1.5% of those of wild-type controls following maceration of ripening fruit.”
Claim · model-written summary
Adding linoleic acid increased flavor volatiles.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- linoleice0
- Outcome
- levels of flavor volatilese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Addition of linoleic or linolenic acid to fruit homogenates significantly increased the levels of flavor volatiles”
t0“Tomato”
Claim · model-written summary
Adding linolenic acid increased flavor volatiles.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- linolenic acide0
- Outcome
- levels of flavor volatilese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Addition of linoleic or linolenic acid to fruit homogenates significantly increased the levels of flavor volatiles”
t0“Tomato”
Claim · model-written summary
The volatile increase after fatty acid addition was lower in TomloxC-depleted extracts than wild type.
- Taxon
- TomatoSolanum lycopersicumt0
- Treatment
- TomloxC-depleted transgenic fruit extractse0
- Outcome
- increasee0
- Direction
- much lowere0
- Comparator
- wild-type controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the increase with the TomloxC-depleted transgenic fruit extracts was much lower than with the wild-type control”
t0“Tomato”
Claim · model-written summary
TomloxC-GFP localized to chloroplasts in tobacco leaf cells.
- Taxon
- tobacco (Nicotiana tabacum)
Nicotiana tabacume0 - Organ / stage
- leaf cellse0
- Gene
- TomloxC-GFPe0
- Outcome
- chloroplast localization of the proteine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Confocal imaging of tobacco (Nicotiana tabacum) leaf cells expressing a TomloxC-GFP fusion confirmed a chloroplast localization of the protein.”
Claim · model-written summary
The authors infer chloroplast-targeted TomloxC can use linoleic and linolenic acids to generate C6 flavor compounds.
- Taxon
- TomatoSolanum lycopersicumt0
- Gene
- TomloxCe0
- Outcome
- volatile C6 flavor compoundse0
- Qualifier
- can use both linoleic and linolenic acids as substratese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“TomloxC is a chloroplast-targeted lipoxygenase isoform that can use both linoleic and linolenic acids as substrates to generate volatile C6 flavor compounds”
t0“Tomato”
The same questions in other papers
loss of function · molecular: expression · Solanum lycopersicum (tomato)Positive and negative results
59 papers in the same direction as this paper · 20 in the opposite direction
- positive
- positive
- positive
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See all 80 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.