| CO2 fixation and water loss of leaves
Prof
Susanne von Caemmerer
In association with Prof
Murray Badger, Dr Asaph Cousins, Irene Baroli
We are investigating aspects
of carbon acquisition by plants including the biochemistry
of fixation and regulation of CO2 diffusion
into and within leaves. Current research honours
topics include:
1) The role of aquaporins and in CO2 diffusion within
leaves.
Aquaporins have been implicated to play a role in
the diffusion of CO2 across membranes such as the
plasma membrane and chloroplast envelope. This project
would involve the characterisation of the physiological
phenotypes of several arabidopisis aquaporin knock
out mutants (in collaboration with Dr JR Evans, Environmental
Biology Group).
2) Analysis of Arabidopsis plants deficient in the
activity of phospho-enol pyruvate (PEP) carboxylase,
an enzyme involved in the regulation of stomatal
function.
There are four PEPcarboxylase genes in Arabidopsis.
At present it is unknown whether all are expressed
in guard cells of leaves. Arabidopsis knock out mutants
exist for all four genes. The project would try to
find out whether the absence of any one of the four
genes affects guard cell function using gas exchange
techniques.
3) Carbon and oxygen isotope exchange in various
C4 grasses.
We have developed mass spectrometric techniques that
allow us to make concurrent measurements of CO2 exchange
and isotope discrimination measurements of 13C
and 18O in CO2.
C4 grasses are responsible for 20% of the global
terrestrial CO2 uptake
and isotopic discrimination during CO2 uptake
is an important atmospheric signal. We would like
to characterise the isotope discrimination properties
of grasses from the different biochemical C4 subtypes.
4) The role of chloroplastic and cytosolic carbonic
anhydrase in photosynthesis. This project will use Arabidopsis knockout
mutants of different CA genes in Arabidopsis to approach
this problem. Plants will be analysed using gas exchange,
biochemical and molecular analysis and carbon and
oxygen isotope exchange techniques mentioned above.
The aim is to measure the extent that each form of
CA contributes to CO2 supply
to the chloroplast during photosynthesis.
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