Structure and function of the plant metabolic network
Metabolic networks supply the precursors, energy and reducing power required for the synthesis and turnover of cellular components. The associated flows of material – the metabolic fluxes – are crucial in determining the performance and productivity of cells and organisms. For example, in an agricultural context, the production of harvestable end-products of plant metabolism is entirely dependent on the flux phenotype of the plant; while in biotechnology, the exploitation of micro-organisms and plants hinges on an ability to reconfigure the metabolic network to favour a flux distribution that leads to the preferential synthesis of particular products. Thus the fluxes supported by the plant metabolic network play a pivotal role in determining both phenotype and productivity.
My main interest lies in understanding the organisation and regulation of the metabolic fluxes that occur in the plant metabolic network. A knowledge of the transcriptome, proteome or metabolome does not lead easily to the metabolic flux phenotype, and internal fluxes within the metabolic network have to be deduced from a suite of computational and experimental tools. My research group is strongly involved in the development and application of steady-state metabolic flux analysis (MFA), a technique that allows fluxes to be deduced from a stoichiometric model of the network using stable isotope (13C) labelling data and measurements of biosynthetic outputs. We complement this MFA work with an in silico approach using genome-scale models and constraints-based flux balance analysis. Together these methods allow us to assess the metabolic phenotypes of wild type, mutant and transgenic plants, and thus the metabolic impact of genetic and environmental perturbations.
Future work will address fundamental questions relating to metabolic network capacity and performance in the tissues of C3, C4 and CAM plants; as well as analyzing the metabolic interactions that occur between cell types in plant tissues, and between plants and microbes.
Current projects include:
- Integrated source-sink metabolic modelling of tomato fruit development.
- Constraints-based metabolic modelling of C4 and CAM photosynthesis.
- A flux analysis perspective on the metabolic capacity of Euglena gracilis.
- Flux analysis of Azorhizobium caulinodans under N2 and non-N2 fixing conditions.
- Effect of charge and proton balancing on constraints-based metabolic models.
- Metabolic analysis of potassium stress in an Arabidopsis suspension culture.
Other areas of interest for future projects:
- Cell- and tissue-specific metabolic flux analysis.
- In silico engineering of CAM photosynthesis and bioenergy crops.
- Provision of reducing power for growth and development.
- Metabolic analysis of osmotolerance in plant pathogens.
- Metabolic flux analysis of symbiotic nitrogen fixation.