Abstract
The role of fructose 2,6 bisphosphate in partitioning of photosynthate between sucrose and starch has been studied in spinach (Spinacia oleracea U.S. hybrid 424). Spinach leaf material was pretreated to alter the sucrose content, so that the rate of starch synthesis could be varied. The level of fructose 2,6-bisphosphate and other metabolites was then related to the accumulation of sucrose and the rate of starch synthesis. The results show that fructose 2,6-bisphosphate is involved in a sequence of events which provide a fine control of sucrose synthesis so that more photosynthate is diverted into starch in conditions when sucrose has accumulated to high levels in the leaf tissue. (a) As sucrose levels in the leaf rise, there is an accumulation of triose phosphates and hexose phosphates, implying an inhibition of sucrose phosphate synthase and cytosolic fructose 1,6-bisphosphatase. (b) In these conditions, fructose 2,6-bisphosphate increases. (c) The increased fructose 2,6-bisphosphate can be accounted for by the increased fructose 6-phosphate in the leaf. (d) Fructose 2,6-bisphosphate inhibits the cytosolic fructose 1,6-bisphosphatase so more photosynthate is retained in the chloroplast, and converted to starch.
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Claims 7
Claim · model-written summary
High leaf sucrose levels were associated with diversion of more photosynthate into starch.
- Taxon
- spinach
Spinacia oleraceae1 - Organ / stage
- leaf tissuee0
- Compound
- sucrosee0
- Outcome
- more photosynthate is diverted into starche0
- Direction
- moree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“more photosynthate is diverted into starch in conditions when sucrose has accumulated to high levels in the leaf tissue”
e1“spinach (Spinacia oleracea U.S. hybrid 424)”
Claim · model-written summary
Rising leaf sucrose was accompanied by accumulation of triose phosphates and hexose phosphates.
- Taxon
- spinachSpinacia oleraceae1
- Organ / stage
- leafe0
- Compound
- sucrosee0
- Outcome
- accumulation of triose phosphates and hexose phosphatese0
- Direction
- accumulatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“As sucrose levels in the leaf rise, there is an accumulation of triose phosphates and hexose phosphates”
e1“spinach (Spinacia oleracea U.S. hybrid 424)”
Claim · model-written summary
Accumulation of phosphates implied inhibition of sucrose phosphate synthase and cytosolic fructose 1,6-bisphosphatase.
- Taxon
- spinachSpinacia oleraceae1
- Outcome
- inhibition of sucrose phosphate synthase and cytosolic fructose 1,6-bisphosphatasee0
- Qualifier
- implyinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“implying an inhibition of sucrose phosphate synthase and cytosolic fructose 1,6-bisphosphatase”
e1“spinach (Spinacia oleracea U.S. hybrid 424)”
Claim · model-written summary
Fructose 2,6-bisphosphate increased under these high sucrose conditions.
- Taxon
- spinachSpinacia oleraceae1
- Outcome
- fructose 2,6-bisphosphatee0
- Direction
- increasese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In these conditions, fructose 2,6-bisphosphate increases”
e1“spinach (Spinacia oleracea U.S. hybrid 424)”
Claim · model-written summary
Increased leaf fructose 6-phosphate accounted for increased fructose 2,6-bisphosphate.
- Taxon
- spinachSpinacia oleraceae1
- Organ / stage
- leafe0
- Compound
- fructose 6-phosphatee0
- Outcome
- increased fructose 2,6-bisphosphatee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The increased fructose 2,6-bisphosphate can be accounted for by the increased fructose 6-phosphate in the leaf”
e1“spinach (Spinacia oleracea U.S. hybrid 424)”
Claim · model-written summary
Fructose 2,6-bisphosphate inhibited cytosolic fructose 1,6-bisphosphatase.
- Taxon
- spinachSpinacia oleraceae1
- Compound
- Fructose 2,6-bisphosphatee0
- Outcome
- inhibits the cytosolic fructose 1,6-bisphosphatasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fructose 2,6-bisphosphate inhibits the cytosolic fructose 1,6-bisphosphatase”
e1“spinach (Spinacia oleracea U.S. hybrid 424)”
Claim · model-written summary
This inhibition retained more photosynthate in chloroplasts and converted it to starch.
- Taxon
- spinachSpinacia oleraceae1
- Organ / stage
- chloroplaste0
- Outcome
- more photosynthate is retained in the chloroplast, and converted to starche0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“so more photosynthate is retained in the chloroplast, and converted to starch”
e1“spinach (Spinacia oleracea U.S. hybrid 424)”