Abstract
The reduction of photosynthetic capacity in many plants grown at elevated CO 2 is thought to result from a feedback effect of leaf carbohydrates on gene expression. Carbohydrate feedback at elevated CO 2 could result from limitations on carbohydrate utilization at many different points, for example export of triose phosphates from the chloroplast, sucrose synthesis and phloem loading, transport in the phloem, unloading of the phloem at the sinks, or utilization for growth of sinks. To determine the relative importance of leaf versus whole plant level limitations on carbohydrate utilization at elevated CO 2 , and the possible effects on the regulation of photosynthetic capacity, we constructed a treatment system in which we could expose single, attached, soybean leaflets to CO 2 concentrations different from those experienced by the rest of the plant. The single leaflet treatments had dramatic effects on the carbohydrate contents of the treated leaflets. However, photosynthetic capacity and rubisco content were unaffected by the individual leaflet treatment and instead were related to the whole plant CO 2 environment, despite the fact that the CO 2 environment around the rest of the plant had no significant affect on the total non‐structural carbohydrate (TNC) contents of the treated leaflets. These results necessitate a re‐evaluation of the response mechanisms to CO 2 as well as some of the methods used to test these responses. We propose mechanisms by which sink strength could influence leaf physiology independently of changes in carbohydrate accumulation.
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Claims 4
Claim · model-written summary
Single leaflet CO2 treatment changed carbohydrate content of treated leaflets.
- Taxon
- soybean
Glycine maxe7 - Treatment
- single leaflet treatmentse0
- Outcome
- carbohydrate contents of the treated leafletse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The single leaflet treatments had dramatic effects on the carbohydrate contents of the treated leaflets”
e7“single, attached, soybean leaflets”
Claim · model-written summary
Individual leaflet CO2 treatment did not affect photosynthetic capacity or rubisco content.
- Taxon
- soybeanGlycine maxe7
- Treatment
- individual leaflet treatmente0
- Outcome
- photosynthetic capacity and rubisco contente0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“photosynthetic capacity and rubisco content were unaffected by the individual leaflet treatment”
e7“single, attached, soybean leaflets”
Claim · model-written summary
Photosynthetic capacity and rubisco content were related to whole-plant CO2 environment.
- Taxon
- soybeanGlycine maxe7
- Treatment
- whole plant CO 2 environmente0
- Outcome
- photosynthetic capacity and rubisco contente0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“photosynthetic capacity and rubisco content were unaffected by the individual leaflet treatment and instead were related to the whole plant CO 2 environment”
e7“single, attached, soybean leaflets”
Claim · model-written summary
The rest-of-plant CO2 environment did not significantly affect treated-leaflet TNC content.
- Taxon
- soybeanGlycine maxe7
- Treatment
- CO 2 environment around the rest of the plante0
- Outcome
- total non‐structural carbohydrate (TNC) contents of the treated leafletse0
- Direction
- no significant affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the CO 2 environment around the rest of the plant had no significant affect on the total non‐structural carbohydrate (TNC) contents of the treated leaflets”
e7“single, attached, soybean leaflets”
The same questions in other papers
co2 · quality: sugar starch · Glycine max (soybean)Positive and negative results
5 papers in the same direction as this paper · 12 in the opposite direction
- positive
- positive
- positive
14 papers more in this group
See all 18 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.