Defining root exudates including signalling molecules released by plant roots for nitrogen acquisition in Australian crops

This joint PhD project will be based at The University of Melbourne with a minimum 12 month stay at the Shanghai Jiao Tong University.

Project description
Plant-microbe interactions are intricate processes that involve underground signalling and communication, followed by modifications in the plant’s biological, morphological and biochemical components. Some proteins, lipids, small RNA’s, and metabolites which are exchanged between plants and microbes are considered signalling molecules for the ‘dialogue’ of plant-microbes. Multiple microbes associated with host plants are known to positively influence plant growth through the production of growth regulating hormones, enhancing plant nutrition, improving the root system architecture of host plants, and protecting plants from biotic or abiotic stresses. Harnessing the new knowledge of the biochemical and genetic basis of plant-microbe interactions in the rhizosphere is a promising direction to innovate the design of new controlled release fertilizer coatings for improved crop nitrogen (N) acquisition in agricultural ecosystems. This project will define the biochemical signalling molecules released and sensed by selected crops (e.g. cotton, wheat or barley) for N acquisition, and their roles in regulating soil N transformations. These signalling molecules (in particular, those relevant to N acquisition) can be used to inform design of new fertilisers and inhibitors.

Key questions:

  1. What are the key signalling molecules for N acquisition for the crops wheat and barley?
  2. What are the key factors that drive the biochemical signals in root exudates of selected plant species?
  3. How do signalling molecules for N acquisition change over the different growth stages of the crops?
  4. How do signalling molecules for N acquisition impact the composition and functions of rhizosphere microbiomes?

 Hypothesis: Signalling molecules for N acquisition are conserved and unique to selected crop plants, and have the great potential to be used in future fertiliser design.

Scope of work

The student will use multiple approaches (molecular biology, root physiology, biochemistry) to identify the mechanisms underpinning the plant root-soil-microbiome interactions under various N availability conditions, and consequently growth and N-use efficiency of target crops. Once a core group of biochemical signal molecules are identified, they can be extracted and selected with the capacity to attract, promote or maintain activities of beneficial N-cycling microbes with positive consequences for plant N acquisition. Signalling molecules can be also selected based on their ability to attract beneficial microbes in the rhizosphere to improve crop resistance to soil stresses, pathogens and diseases.

These analyses will be supported by high-end microscopy within the UoM Microscopy platform, by metabolite, lipid and stable isotope profiling through Metabolomics Australia, by small RNA profiling through the Australian Genome Research Facility and by protein and peptide profiling through the Melbourne Mass Spectrometry Facility.

Supervision team:
Professor Ute Roessner (The University of Melbourne) (primary contact for UM based student), Dr Hang-Wei Hu, Prof Deli Chen, and Professor Staffan Persson (The University of Melbourne/University of Copenhagen)

Professor Dabing Zhang (Shanghai Jiao Tong University) (primary contact with SJTU based student)

How to apply

If you are interested in this opportunity, read the application guidelines before contacting the lead supervisor.