Abstract
BACKGROUND: Following on from recent advances in plant AsA biosynthesis there is increasing interest in elucidating the factors contributing to the L-ascorbic acid (AsA) content of edible crops. One main objective is to establish whether in sink organs such as fruits and tubers, AsA is synthesised in situ from imported photoassimilates or synthesised in source tissues and translocated via the phloem. In the current work we test the hypothesis that long-distance transport is involved in AsA accumulation within the potato tuber, the most significant source of AsA in the European diet. RESULTS: Using the EDTA exudation technique we confirm the presence of AsA in the phloem of potato plants and demonstrate a correlation between changes in the AsA content of source leaves and that of phloem exudates. Comparison of carboxyflourescein and AgNO3 staining is suggestive of symplastic unloading of AsA in developing tubers. This hypothesis was further supported by the changes in AsA distribution during tuber development which closely resembled those of imported photoassimilates. Manipulation of leaf AsA content by supply of precursors to source leaves resulted in increased AsA content of developing tubers. CONCLUSION: Our data provide strong support to the hypothesis that long-distance transport of AsA occurs in potato. We also show that phloem AsA content and AsA accumulation in sink organs can be directly increased via manipulation of AsA content in the foliage. We are now attempting to establish the quantitative contribution of imported AsA to overall AsA accumulation in developing potato tubers via transgenic approaches.
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Claims 8
Claim · model-written summary
Ascorbic acid was detected in potato phloem.
- Taxon
- potato
Solanum tuberosume0 - Outcome
- presence of AsA in the phloeme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“confirm the presence of AsA in the phloem of potato plants”
Claim · model-written summary
Source leaf and phloem exudate ascorbic acid contents covaried.
- Taxon
- potatoSolanum tuberosumt0
- Organ / stage
- source leavese0
- Outcome
- phloem exudatese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“correlation between changes in the AsA content of source leaves and that of phloem exudates”
t0“potato”
Claim · model-written summary
Staining suggested symplastic unloading of ascorbic acid in developing tubers.
- Taxon
- potatoSolanum tuberosumt0
- Outcome
- symplastic unloading of AsA in developing tuberse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Comparison of carboxyflourescein and AgNO3 staining is suggestive of symplastic unloading of AsA in developing tubers”
t0“potato”
Claim · model-written summary
Ascorbic acid distribution changes resembled those of imported photoassimilates during tuber development.
- Taxon
- potatoSolanum tuberosumt0
- Organ / stage
- tuber developmente0
- Outcome
- changes in AsA distributione0
- Comparator
- imported photoassimilatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“changes in AsA distribution during tuber development which closely resembled those of imported photoassimilates”
t0“potato”
Claim · model-written summary
Supplying precursors to source leaves increased ascorbic acid in developing tubers.
- Taxon
- potatoSolanum tuberosumt0
- Treatment
- supply of precursors to source leavese0
- Outcome
- AsA content of developing tuberse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Manipulation of leaf AsA content by supply of precursors to source leaves resulted in increased AsA content of developing tubers”
t0“potato”
Claim · model-written summary
The results support long-distance transport of ascorbic acid in potato.
- Taxon
- potatoSolanum tuberosume0
- Outcome
- long-distance transport of AsAe0
- Qualifier
- strong supporte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“strong support to the hypothesis that long-distance transport of AsA occurs in potato”
Claim · model-written summary
Changing foliage ascorbic acid directly increased phloem ascorbic acid content.
- Taxon
- potatoSolanum tuberosumt0
- Treatment
- manipulation of AsA content in the foliagee0
- Outcome
- phloem AsA contente0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phloem AsA content and AsA accumulation in sink organs can be directly increased via manipulation of AsA content in the foliage”
t0“potato”
Claim · model-written summary
Changing foliage ascorbic acid directly increased accumulation in sink organs.
- Taxon
- potatoSolanum tuberosumt0
- Treatment
- manipulation of AsA content in the foliagee0
- Outcome
- AsA accumulation in sink organse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phloem AsA content and AsA accumulation in sink organs can be directly increased via manipulation of AsA content in the foliage”
t0“potato”
The same questions in other papers
L-ascorbic acid · molecular: metabolites · Solanum tuberosum (potato)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- positive
- negative
- 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.