Skip to main content

Regulation of root growth in response to phosphate availability

Principal Supervisor: Alex Jones - SLS

Co-supervisor: Elizabeth Wellington - SLS

PhD project title: Regulation of root growth in response to phosphate availability

University of Registration: University of Warwick

Project outline:

Our food supply relies on plants, either directly through consumption of leaves, seeds and roots or as feedstock for animals. Food shortages may seem unimaginable to Europeans but the effects of drought, climate change and poor soils all contribute to the devastating effects of poverty. If you are unmoved by the plight of others, Europe might not be immune to global changes; for example, the UK imports roughly 60% of its food. One contributing factor to soil quality is the availability of the essential micronutrient phosphorus (P) which often limits plant growth, reduces crop yields and requires the application of fertilizer. Approximately, 15 million tonnes of phosphorus are mined annually to meet global needs for fertilizer, but this resource is limited and could be exhausted in as little as 30 years. Substantial amounts of phosphate are lost through inefficiencies in application, leaching from the soil and poor uptake by plants. Lost P fertilizer can cause environmental damage to freshwater systems through eutrophication. Therefore, if we can improve how plants take up P from the soil, we can contribute in a meaningful way to improving food security. The objective of this project is to understand, at the molecular level of proteins, how plants adapt root growth in response to low P conditions.

Plant root growth might seem simple, but roots adapt rapidly to changing environmental conditions such as the availability of water, nutrients, microbes and adverse conditions such as salinity. The roots of the model plant Arabidopsis thaliana display rapid and dramatic changes in response to low P; they become very hairy. Root hairs are simple tubular protrusions from epidermal cells, they grow quickly and provide an excellent method to very rapidly increase the surface area of a root. We know some of the key molecular players in regulating root hair growth; a plasma membrane receptor called FERONIA is essential for correct tubular growth, small GTPases called ROPs are required for determination of polarity in root hair extension and directed vesicle trafficking is critical. But we know very little about how the activity of these proteins are coordinated to generate responsive root growth.

Current research in the Jones group is focused on identifying interaction partners of FERONIA and ROPs, and affinity enrichment methods have allowed the identification of hundreds of proteins associated with regulating vesicle traffic (Heard et al. 2015). This PhD project aims to clarify the signal pathways and trafficking events that drive rapid growth of root hairs in response to low P. Because the roots of Arabidopsis are relatively small and grow rapidly they make an excellent model system and are suitable for live cell imaging as well as phenotypic screening. The first year of the project will focus on proteomics and genetic manipulation (in A. thaliana) to identify and test putative components of the signal pathway and its downstream targets. The second year will move on to biophysical characterisation of identified interactors. The final years will use synthetic gene constructs to mimic phosphorylation, in conjunction with imaging and modelling approaches to determine cell type specificity and propagation of local signal initiation across the root.

References:

  1. Heard W, Sklenãr J, Tomé DFA, Robatzek S, Jones AME. (2015) Identification of regulatory and cargo proteins of endosomal and secretory pathways in Arabidopsis thaliana by proteomic dissection. MCP 14 (7) 1796-1813

BBSRC Strategic Research Priority: Food security

Techniques that will be undertaken during the project:

  • Cloning and expression of modified proteins in plants and bacteria
  • Protein biochemistry; purification of protein complexes
  • Protein interaction analysis
  • Quantitative proteomics using mass spectrometry
  • In vivo light microscopy (confocal, spinning disc, TIRF)
  • Image and data analysis of protein and hormone reporters
  • Modeling of proteins and hormone dynamics across roots

Contact: Dr Alex Jones, University of Warwick