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Published: 12 Mar 2021

A new laboratory test to rapidly screen potato varieties for resistance to powdery scab disease, has been developed by researchers at the Tasmanian Institute of Agriculture (TIA).

Powdery scab disease is currently one of the biggest constraints to potato production and sales in Australia resulting in annual multi-million dollar losses across all potato industry sectors.

Infection first occurs in the potato roots and it is this phase of the disease that is exciting researchers as both a focus for screening new varieties and for developing new controls.

Once root infection occurs, the disease progresses rapidly leading to reductions in tuber yields and unsightly tuber lesions.

Tasmania is the perfect test lab for research into powdery scab disease with ideal disease conditions which favours a cool, moist environment in heavy soils.

The latest research from TIA has developed a laboratory test which rapidly assesses a new potato variety’s susceptibility to the disease at the root infection phase, much quicker than traditional screening methods that rely on glasshouse or field testing.

Project lead, Professor Calum Wilson said that targeting early stages of root infection was the key to this screening technique.

“The importance of this early phase of root infection cannot be underestimated,” he said.

“Interventions at this stage can provide major benefits in disease as this is when the powdery scab pathogen releases its motile spores that swim through the soil water and bind to potato roots leading to infection and disease.”

Traditionally screening methods require either glasshouse or field trials growing potato in pathogen-infested soil in large, replicated experiments, which can take many months to complete as the potato plant needs to grow through to full maturity.

The results, especially in field trials, can also be variable as soil-borne sources of pathogen may be patchy across the trial site.

Professor Wilson said the new screening test would provide major benefits to industry in its simplicity, consistency, economy and efficient turn-around of results. It also provides a valuable tool to test new control treatments for their capacity to reduce disease.

“The new test we have developed allows varieties to be tested within a period of days without having to leave the laboratory, greatly reducing the time required for screening and costs associated with resource and skilled labour inputs,” he said.

The project is also looking closely at how the motile spores bind to roots and the mechanisms involved.  By working out how known resistant varieties reduce root infection TIA researchers aim to   establish new controls that could prevent root infection alongside new tools to assist breeding for disease resistance.

The research is part of a three-year TIA research project into improving the understanding, diagnosis and control strategies associated with Spongospora root diseases of potato.

This project has been funded by Hort Innovation, using the processing and fresh potato research and development levies and kind contributions from TIA and the Australian Government. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.

TIA is a joint venture between the University of Tasmania and the Tasmanian Government.

Image caption:  

Professor Calum Wilson and PhD candidate Xian Yu inspecting tissue culture potatoes for use in rapid disease screening.