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
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
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
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
Phloem unloading of sucrose: cloning, functional characterisation and regulation of novel membrane transporters. Sucrose is the principal form in which plant biomass, produced in photosynthetic leaves, is transported to non-photosynthetic organs for growth and storage. Sucrose transport proteins play pivotal roles in facilitating sucrose transport around plants. Hence activities of sucrose transporters directly impact on plant growth rates and crop yields. Our aim is to isolate hitherto unkno ....Phloem unloading of sucrose: cloning, functional characterisation and regulation of novel membrane transporters. Sucrose is the principal form in which plant biomass, produced in photosynthetic leaves, is transported to non-photosynthetic organs for growth and storage. Sucrose transport proteins play pivotal roles in facilitating sucrose transport around plants. Hence activities of sucrose transporters directly impact on plant growth rates and crop yields. Our aim is to isolate hitherto unknown membrane proteins that move sucrose at high rates between cells and discover their transport properties. Expected outcomes are to better understand mechanisms and regulation of sucrose transport and hence provide novel opportunities to enhance crop yield. The project will foster a productive international collaboration.Read moreRead less
The response of mitochondria to oxidative stress in plants. Crops encounter many situations in their environment which place them under stress. Reactive oxygen molecules produced in these situations act as messengers to trigger defence mechanisms but also cause cellular damage. Mitochondria are the subcellular compartments involved in energy production and are essential for plant development and growth. However, they also have been implicated in the response of plants to stress and pathogen atta ....The response of mitochondria to oxidative stress in plants. Crops encounter many situations in their environment which place them under stress. Reactive oxygen molecules produced in these situations act as messengers to trigger defence mechanisms but also cause cellular damage. Mitochondria are the subcellular compartments involved in energy production and are essential for plant development and growth. However, they also have been implicated in the response of plants to stress and pathogen attack, and in production of reactive oxygen molecules. This proposal seeks to investigate how mitochondria are involved in these processes, focusing on the role of terminal oxidases. Potential outcomes include crops better able to cope with environmental stress.Read moreRead less
A novel role for phytochrome in dormancy release inhibition. Seed dormancy contributes to the persistence of weeds in agriculture by enabling seeds to remain viable in the soil for many years, and is a major reason why annual ryegrass (Lolium rigidum) has become the most economically damaging weed in Australian agriculture. Recently we discovered a new way to control dormancy release and germination in these seeds. This project to identify the changes occurring within the seeds during dormancy r ....A novel role for phytochrome in dormancy release inhibition. Seed dormancy contributes to the persistence of weeds in agriculture by enabling seeds to remain viable in the soil for many years, and is a major reason why annual ryegrass (Lolium rigidum) has become the most economically damaging weed in Australian agriculture. Recently we discovered a new way to control dormancy release and germination in these seeds. This project to identify the changes occurring within the seeds during dormancy release will underpin our efforts to manipulate emergence timing in order to improve the efficacy of current weed control practices and contribute to sustainable farming systems.Read moreRead less
Multifunctional channels as key components of biotrophic interfaces in legumes. In legumes there are two types of membrane interfaces between different genomes that are critical for growth and yield (nitrogen fixation and seed loading), which require cell-signalling pathways to control nutrient exchange. The membranes of these interfaces contain specialised proteins that form multifunctional channels through which water, uncharged molecules and electrolytes move. These channels are likely to be ....Multifunctional channels as key components of biotrophic interfaces in legumes. In legumes there are two types of membrane interfaces between different genomes that are critical for growth and yield (nitrogen fixation and seed loading), which require cell-signalling pathways to control nutrient exchange. The membranes of these interfaces contain specialised proteins that form multifunctional channels through which water, uncharged molecules and electrolytes move. These channels are likely to be responsible for supporting the bulk of transported nutrients and in controlling their exchange. We aim to discover how these channels function in nitrogen fixation and seed loading with a view to developing new technologies that may enhance crop productivity.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