Disorder as a novel determinant of photosynthetic structure and function: an experimental study. Australia enjoys a world reputation in photosynthesis research, typified by hosting the 2001 International Photosynthesis Congress. It also has a claim to fame for theoretical work in non-equilibrium thermodynamics concerning production of disorder or entropy, yielding new insights into planetary climates. This experimental project investigates the novel relation between entropy/entropy production ....Disorder as a novel determinant of photosynthetic structure and function: an experimental study. Australia enjoys a world reputation in photosynthesis research, typified by hosting the 2001 International Photosynthesis Congress. It also has a claim to fame for theoretical work in non-equilibrium thermodynamics concerning production of disorder or entropy, yielding new insights into planetary climates. This experimental project investigates the novel relation between entropy/entropy production and the structure/function of the solar powerhouse of plants (chloroplasts), and addresses fundamental questions at the interface of biology and physics. The research explores chloroplasts as a manifestation of the all-pervading Second Law of Thermodynamics, advancing Australia's contribution to basic science and helping to train researchers.Read moreRead less
Molecular analysis of photosynthetically-linked, active CO2 uptake and CO2 signal transduction by cyanobacteria (blue-green algae). Cyanobacteria (blue-green algae) have evolved a very efficient means of capturing and concentrating CO2 for photosynthetic fixation into sugars, the basic building blocks for cell growth. This process is dependent on the operation of several unique, active uptake systems for CO2 and HCO3-, with their genetic expression regulated by CO2 supply. This proposal will cap ....Molecular analysis of photosynthetically-linked, active CO2 uptake and CO2 signal transduction by cyanobacteria (blue-green algae). Cyanobacteria (blue-green algae) have evolved a very efficient means of capturing and concentrating CO2 for photosynthetic fixation into sugars, the basic building blocks for cell growth. This process is dependent on the operation of several unique, active uptake systems for CO2 and HCO3-, with their genetic expression regulated by CO2 supply. This proposal will capitalize on our progress in describing the functional genetics of this process and aims to elucidate the mechanism of active CO2 uptake and the way that cells sense the ambient CO2 concentration. The information gained is likely to be useful for designing improved crops.Read moreRead less
What limits CO2 diffusion inside leaves? Dissecting the diffusion path with Arabidopsis mutants. Human induced increase in atmospheric carbon dioxide is now generally accepted as contributing to global warming. Forecasting our future impact relies on models of terrestrial photosynthesis which use a signature in the atmosphere created by plants when they discriminate against the heavy stable isotope of carbon during photosynthesis. Discrimination between isotopes is affected by carbon dioxide dif ....What limits CO2 diffusion inside leaves? Dissecting the diffusion path with Arabidopsis mutants. Human induced increase in atmospheric carbon dioxide is now generally accepted as contributing to global warming. Forecasting our future impact relies on models of terrestrial photosynthesis which use a signature in the atmosphere created by plants when they discriminate against the heavy stable isotope of carbon during photosynthesis. Discrimination between isotopes is affected by carbon dioxide diffusion within leaves and key steps in this process will be identified through the use of Arabidopsis mutants. Better representation of this process in models will improve estimates of terrestrial photosynthesis and climate change forecastsRead moreRead less
Probing the four photosynthetic membrane protein complexes at work in situ in leaves. This proposal aims at sustainable improvements in plant productivity and photosynthetic adaptation in drastic Australian climates. In photosynthesis, membranes with the four multiprotein complexes use sunlight to make compounds that drive carbon assimilation. Instead of the usual dissection of photosynthetic membranes, this project will develop and refine the applicant's rapid, reliable, non-intrusive technique ....Probing the four photosynthetic membrane protein complexes at work in situ in leaves. This proposal aims at sustainable improvements in plant productivity and photosynthetic adaptation in drastic Australian climates. In photosynthesis, membranes with the four multiprotein complexes use sunlight to make compounds that drive carbon assimilation. Instead of the usual dissection of photosynthetic membranes, this project will develop and refine the applicant's rapid, reliable, non-intrusive techniques to probe the four membrane complexes at work in their native state in leaves. Two portable commercial instruments will potentially emerge from the techniques. This novel non-reductionist approach will identify key limitations to photosynthetic performance under stress, and insights into improvements for primary plant productivity.Read moreRead less
Unsaturation of vapour pressure inside leaves: fundamental, but unknown. This project aims to determine when and to what extent the air inside leaves becomes unsaturated with water vapour. All current interpretation and modelling of leaf gas exchange assumes saturation under all circumstances. Compelling evidence has been obtained that suggests this is not true under moderate air vapour pressure deficits. A novel technique will be employed to assess the water vapour concentration of the air insi ....Unsaturation of vapour pressure inside leaves: fundamental, but unknown. This project aims to determine when and to what extent the air inside leaves becomes unsaturated with water vapour. All current interpretation and modelling of leaf gas exchange assumes saturation under all circumstances. Compelling evidence has been obtained that suggests this is not true under moderate air vapour pressure deficits. A novel technique will be employed to assess the water vapour concentration of the air inside leaves based on stable isotope analysis of carbon dioxide and water vapour exchanged between leaves and air. The project is expected to provide fundamental knowledge about how stomata regulate photosynthesis and water use, with significant implications for modelling vegetation function and for improving the performance of crop plants.Read moreRead less
Photosynthetically active bicarbonate transporters from cyanobacteria & their rational redesign for application in engineered crops that use less water. Marine blue-green algae are critical components of global primary productivity and fisheries productivity but CO2 acquisition processes in these organisms are poorly understood. Our aim is to determine the protein structure and regulatory controls present in two classes of cyanobacterial bicarbonate transporters that are required for efficient p ....Photosynthetically active bicarbonate transporters from cyanobacteria & their rational redesign for application in engineered crops that use less water. Marine blue-green algae are critical components of global primary productivity and fisheries productivity but CO2 acquisition processes in these organisms are poorly understood. Our aim is to determine the protein structure and regulatory controls present in two classes of cyanobacterial bicarbonate transporters that are required for efficient photosynthesis. This information is now critical to the our goal of redesigning these bicarbonate transporters so they will be functional in plants, thereby contributing to the applied objective of engineering crop plants that could produce good grain yields with reduced water requirements.Read moreRead less
Will stomatal responses to humidity and carbon dioxide constrain tropical forest productivity as atmospheric carbon dioxide rises? This project will investigate two physiological processes that will partly determine growth responses of tropical forest trees to rising atmospheric carbon dioxide. The project will produce equations summarising physiological responses that can be incorporated into process-based models of tropical forest productivity.
Reading the isotopic archive: carbon and oxygen stable isotope ratios as recorders of plant physiological processes. This project will investigate how plant physiological processes are reflected in stable isotope ratios of carbon and oxygen in plant tissues. Results will contribute towards a mechanistic understanding of the processes that cause isotopic modifications, thereby enabling an improved interpretation of naturally occurring stable isotope signals.