Project Leader, Organisation

Alistair McTaggart, University of Queensland

Status

Active.

Background

A very high priority in the Myrtle Rust Action Plan is to prevent arrival of new strains of Austropuccinia psidii (Objective 5.1). The project collaborators in the United States, led by Ned Klopfenstein, are developing much-needed, high-throughput sequencing tools to distinguish strains of myrtle rust.

A high priority in the Myrtle Rust Action Plan is to monitor the population of Austropuccinia psidii in Australia for changes (Objective 5.3). These changes can arise from either introduction of new genetic diversity (incursions of new strains), or by mutation and sexual reproduction in the current genotype (currently considered clonal in Australia).

Objectives and impact

Objectives
1. Foster collaborations between researchers from Australia, the USDA (United States of America), Scion (New Zealand) and FABI (South Africa), and provide DNA of Austropuccinia psidii from South Africa to determine genetic loci that distinguish strains of myrtle rust.
2. Determine the disease cycle of A. psidii in Australia through study of sexual reproduction.

Methods
1. Extract genomic DNA from South Africaand send to the USDA team (Obj1).
2. Test efficacy of whole-genome-amplification kits to amplify DNA from single pustules (Obj2).
3. Amplify single pustules collected over three years for genotyping by sequencing (Obj2).
4. Test for evidence of recombination or clonality to determine disease cycle and epidemiology (Obj2).

Outputs
Two published papers on (i) a diagnostic method to distinguish strains of A. psidii and (ii) its disease epidemiology in Australia.

Outcomes
– First resource to identify different strains of A. psidii from single pustules (Obj1).
– Knowledge of whether resistance-screening in our native environments, and tea-tree, lemon myrtle, forestry and honey industries must accommodate a clone or a changing pathogen (Obj2).

Impact
Preparedness to distinguish strains of A. psidii for a rapid biosecurity response in future invasion events and knowledge to guide breeding/conservation programs for native Myrtaceae.