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Award details
Biosynthesis, function and manipulation of branched chain compounds related to CA1P
Reference
BBS/E/C/00004557
Principal Investigator / Supervisor
Professor Martin Parry
Co-Investigators /
Co-Supervisors
Institution
Rothamsted Research
Department
Rothamsted Research Department
Funding type
Research
Value (£)
955,706
Status
Completed
Type
Institute Project
Start date
01/04/2003
End date
31/03/2008
Duration
60 months
Abstract
2-Carboxyarabinitol 1-phosphate (CA1P) limits photosynthetic CO2 assimilation at low light. The pathway for CA1P biosynthesis from newly assimilated carbon uses the Calvin cycle intermediate fructose 1,6 bisphosphate (FBP), which is converted to hamamelose bisphosphate (HBP), dephosphorylated to hamamelose (H), oxidised to 2-carboxyarabinitol (CA) and then phosphorylated to CA1P. This was confirmed by means of pulse chase experiments and analysis of plants with increased amounts of FBP. We have identified, sequenced and cloned the cDNA encoding CA1P-phosphatase. Analysis of transgenic potato plants expressing the gene for chloroplastic FBP phosphatase in the antisense orientation revealed not only more fructose bisphosphate but also more HBP, H, CA and CA1P than their wild-type counterparts. In some cases the hamamelose and CA were as abundant as sucrose. Elements of this pathway are ubiquitous among plant species - significant amounts of H and CA have been detected in wheat and maize that do not synthesise sufficient CA1P to have a significant effect on Rubisco catalytic activity. One intriguing aspect arising from this work relates to the fate of the significant amounts of H and CA in plants in which it is not used for CA1P synthesis. CA1P biosynthetic pathway represents the only known source of all related branch chain compounds (such as H and CA). If these compounds were unnecessary, then such partitioning would decrease the efficiency of photoassimilation. Conversely, since hamamelose is ubiquitous amongst higher plants it probably has an indispensable role in plants. Key objectives are to: 1) Express CA1P phosphatase domains in vitro and test for catalytic activity, manipulate amounts of CA1P phosphatase in vivo 2) identify genes responsive to hamamelose and examine the expression patterns of these genes 3) identify knockout lines 4) determine the extent to which the branched chain compounds are involved in signalling C and N supply and partitioning.
Summary
unavailable
Committee
Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics
X – not assigned to a current Research Topic
Research Priority
X – Research Priority information not available
Research Initiative
X - not in an Initiative
Funding Scheme
X – not Funded via a specific Funding Scheme
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