This project will evaluate two of the newer discovery platforms, proteomics and metabolomics, for effectiveness in the identification of functional biomarkers that differentiate closely related bacterial pathovars. Diagnostics based on functional molecules linked to pathogenicity overcome the limitations of many diagnostics based on anonymous, plasmid-borne or incidental targets. Selected biomarkers will be adapted to reliable, high throughput, rapid turn-around diagnostics for the model organisms.

What is the biosecurity problem?

By definition, bacterial pathovars are distinguished by their host specificity. However, whilst pathogenicity testing on plants is the only definitive means to distinguish between closely related pathovars, such bioassays are fraught with difficulties. The inability to differentiate between pathovars can potentially delay diagnosis and incursion management. Rapid serological and molecular tests are available and fully validated for some exotic bacterial pathovars but for many organisms better diagnostic targets are required to rapidly and specifically differentiate exotic pathovars from closely related endemics.

This project will evaluate proteomics and metabolomics, platforms that identify functional molecules, for their ability to identify unique biomarkers that distinguish between closely related, but distinct, bacterial pathovars. Such biomarkers are likely to be associated with the plant-pathogen interaction and thus the host specificity of the pathovars. They therefore represent the ideal target for robust diagnostics, overcoming many of the practical limitations of assays based on anonymous, plasmid-borne or incidental targets. Additionally, such biomarkers may allow detection of infection before symptoms become evident.

Once identified, selected biomarkers will be adapted to reliable, high throughput, rapid turn-around diagnostics, offering improved laboratory diagnostics in the first instance but potentially amenable to adaptation for in-field use.

Model organisms will be selected for this study but the technology is expected to translate to pathovars of other bacterial species. The project will deliver an improved understanding of plant/pathogen interactions and the relative value of these approaches as tools for discovering practical diagnostic targets.

The main output of this project is:

• evaluate new platforms for use as discovery tools
• develop new diagnostic tests for model organism(s), and
• identify biomarkers that could be evaluated in different delivery platforms.

The target output is two manuscripts.

Who will be the end-users of this research?

Initial users of this research are the accredited laboratory-based diagnosticians responsible for diagnosis of diseases caused by the model organisms. This includes the project team and other partners in the CRCNPB. If suitable and validated biomarkers are identified, there should be no impediment to immediate use. New targets can later be developed into less specialised diagnostic tools for use by quarantine officers, field officers etc.