Award details

Biosynthesis, function and manipulation of branched chain compounds related to CA1P

ReferenceBBS/E/C/00004557
Principal Investigator / Supervisor Professor Martin Parry
Co-Investigators /
Co-Supervisors
Institution Rothamsted Research
DepartmentRothamsted Research Department
Funding typeResearch
Value (£) 955,706
StatusCompleted
TypeInstitute Project
Start date 01/04/2003
End date 31/03/2008
Duration60 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 TopicsX – not assigned to a current Research Topic
Research PriorityX – Research Priority information not available
Research Initiative X - not in an Initiative
Funding SchemeX – not Funded via a specific Funding Scheme
terms and conditions of use (opens in new window)
export PDF file