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Danger signalling – a multicomponent dialogue priming a plant against pathogens. How a leaf warns the rest of the plant from danger – systemic signalling in immunity

Principal Supervisor: Professor Murray Grant, School of Life Sciences

Co-supervisor: Patrick Schäfer, School of Life Sciences

PhD project title: Danger signalling – a multicomponent dialogue priming a plant against pathogens. How a leaf warns the rest of the plant from danger – systemic signalling in immunity

University of Registration: University of Warwick

Project outline:

A major challenge today is to alleviate the > 25% of crop losses globally to plant pathogens. Plants use disease resistance gene (R) products to protect themselves but pathogens can evolve to evade this recognition mechanism.

Upon recognition R protein activate a rapid hypersensitive cell death programme that contains the pathogen. Simultaneously, R proteins also activate a systemic immune response allowing infected tissues to tell the rest of the plant that it is in danger. If we can understand this language that leads establishment of systemic immunity then there is enormous biotechnological potential to enhance crop yields.

Our current understanding of plant long distance signalling is rudimentary. Distal communication requires signal(s) generation in the local sensing leaf, its long distance translocation, delivery to, and decoding of, in the distal responding tleave(s). This is a fascinating area and we have developed a suite of tools based upon the model pathosystem, Arabidopsis thaliana carrying the RPM1 Disease resistance gene and Pseudomonas syringae carrying (or not) the virulence gene avrRpm1, whose gene product is recognised by RPM1 to activate systemic signalling

This project will complete some very exciting results that implicates jasmonate based plant hormone signalling in activating systemic immunity. Using the promoter of a unique systemic signalling responsive gene we can show that challenge with avirulent DC3000avrRpm1 but not virulent DC3000 activates rapid systemic signalling 3.5 h after infection (A). This is totally dependent on the Arabidopsis jasmonate receptor RPM1 (B). Moreover, a promoter-GFP fusion shows that A70 is translocated through the phloem (C) and in the systemic responding leaf localised to plasmdesmata (D). These figures illustrate the very dynamic temporal nature to transcriptional reprogramming in systemic responding naïve leaves.

Pic 1

The project will expand on this work, and incorporate other signaling mutants, transcriptomics and physiology based experiments to dissect our understanding of systemic signaling, thus providing the knowledge to deploy systemic immunity effectively in the field.

BBSRC Strategic Research Priority: Food Security

Techniques that will be undertaken during the project:

  • Plant pathology – local infection and systemic immune assays including bacterial enumeration.
  • Bioimaging – both whole plant transcriptional dynamics using luciferase based assays and sub-cellular transport using YFP & GFP derivatives.
  • Electrophysiology – basic electrophysiology looking at electrical potentials generated during challenges in different mutants.
  • Basic plant genetics and reverse genetics.
  • Transcriptomic profiling and data analysis
  • Metabolomics. Application of both targeted – hormones - and untargeted profiling on phloem exudates and systemic responding leaves.

Contact: Professor Murray Grant, School of Life Sciences