How does a root change its ability to grow through different layers of soil?

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
Roots critically support plant growth, facilitating nutrient and water uptake and anchoring plants to the ground. Understanding root biology is therefore central to sustain agriculture. Soil compaction, caused by farm machinery and water distribution, negatively impacts root growth. Directed root growth is controlled by internal turgor that drives cell expansion and by localized deposition of plant cell walls. In this project, the PhD student will aim to understand how changes in these parameters assist root growth through compacted soils and to provide computational predictions to enhance root growth in affected soils.

Key questions:

  1. How does the overall root architecture and its cell wall thickness change with growth through soils with different densities?
  2. How do cell wall defects change the roots’ ability to penetrate different soil layers?
  3. What types of cell wall alterations are needed to sustain root growth through compacted soils?
  4. Can we develop mathematical, computational models to mimic root behaviour on compacted soils?
  5. Can we use such models to predict what cell wall modifications may allow for better soil penetration of roots?

Hypothesis: genes involved in plant cell wall synthesis regulate the ability of roots to penetrate hard soils, and thereby can be used in future to improve root functions.

Scope of work
The student will investigate how cell wall composition, thickness and architecture changes in roots when they are exposed to a soil layer with different compactness/ density. These analyses will focus on the root elongation zone, which drives root growth. The student will use cell wall mutants and cell wall synthesis inhibitors to assess how mutants behave when exposed to media with high density. It is envisioned that the student will use:

  1. Advanced light and electron microscopy to visualize cell wall thickness and wall anisotropy by investigating microtubule organization and cellulose synthesis (both via live cell imaging on vertical stage and via cellulose- binding dyes);
  1. Cell wall measurements (including antibodies and biochemical analyses) to appreciate cell wall changes in the elongation zone; and
  2. X-ray computed tomography for imaging the roots of cell wall deficient plants to understand the function of cell walls for root growth on compact soils/ media, in collaboration with Prof. Bennett at the University of Nottingham, UK; and
  3. Mathematical modelling with Prof. Zoran Nikoloski at the MPIMP-Golm and University of Potsdam, Germany, to predict how defects in cell wall stability may change the ability of the root to penetrate denser layers of soil for root improvement.

The student will use the model organism Arabidopsis with a leading team of international researchers with root, cell wall, genetic, imaging and mathematical modelling backgrounds.

The investigations should form a basis to better understand how plants adapt their roots to survive in challenging conditions. The project will be complemented by the project using the crop species rice, on how do environmental factors regulate cytoskeleton and cell wall synthesis in rice seedlings to be conducted by another joint PhD student from Shanghai Jiao Tong University. The collaboration will ensure a successful completion of the project.

Supervision team:

Professor Michelle Watt (The University of Melbourne) (primary contact for UM based student)

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.