CRC60134: Potato Spindle Tuber Viroid - PhD

This project will investigate the phylogeny, pathogenicity and epidemiology of potato spindle tuber viroid (PSTVd) and related pospiviroids in Australia.

What is the biosecurity problem?

Since 2001 there have been six reported incursions of PSTVd in tomatoes in Australia. In each instance, an intense eradication program has successfully removed the source of inoculum. As a result of these successful eradication programs PSTVd is still considered a quarantine pest of significance in Australia.

It is critically important to Australian horticulture, particularly the potato industry, that Australia remains free of this destructive pathogen. An investigation into the potential entry pathways of PSTVd in tomatoes is therefore required.

Recent research in Europe has suggested that PSTVd infection may be widespread in certain wild solanaceous hosts, and that these infection reservoirs rather than seed transmissions in tomato may be responsible for outbreaks in tomato in different parts of the world. Recent research in Western Australia also suggests that certain wild non-solanaceous hosts may be involved.

The main outputs of this project are to?

• identify the strains of PSTVd and related pospiviroids that are associated with tomatoes in Australia
• assess the pathogenicity of isolates of PSTVd and related pospiviroids found in Australia on tomato and potato
• identify alternative hosts of PSTVd and the role they play in the emergence of PSTVd incursions in tomatoes in Australia
• evaluate the dynamics of PSTVd epidemics in the field, how contact transmission occurs, and the survival of its infectivity on different surfaces and the role of nurseries as potential reservoirs
• determine what types of scientific data are required to support import risk assessments of solanaceous plant products into Australia
• revise containment and eradication strategies for this harmful pests and diseases, and
• train a post graduate student in Plant Virology (viroids) and Plant Biosecurity.

Who will be the end-users of your research?

Office of the Chief Plant Protection Officer, Biosecurity Australia, Plant Health Australia, state and territory department of primary industries, vegetable industries.