A new look at disease (5 Mar 2019)

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CRDC-supported Honours student Aphrika Gregson is providing a new ‘picture’ of Verticillium wilt.

The new images portray Verticillium wilt as it’s never been seen before in Australia.

Using a fluorescent protein that allows the pathogen to be visualised in an infected cotton plant or host (using confocal laser microscopy), Aphrika and a team from University of Queensland are working to identify and confirm Verticillium dahliae disease entry and infection pathways in cotton plants.

They are using use the green fluorescent protein (GFP) gene inserted into different V.dahliae isolates to determine if a plant is a host of Verticillium, its level of infection and the spread through the plant. Similar technology was used by the Australian banana industry to fight the devastating Panama 4 disease. CRDC recognised a fit with the cotton industry’s search for a deeper understanding of Verticillium wilt.

As part of CRDC’s Innovative solutions to Cotton Diseases project, Aphrika’s preliminary research has focused on adapting the technique from Panama to V. dahliae, before applying the transformed strains to look at infection, virulence and host colonisation by the pathogen.

“So far, we have had promising success introducing the GFP gene into several V. dahliae strains,” Aphrika says.

“At the moment I’m undertaking an assay of the transgenic strains on cotton.

“The GFP appears to be stable and the pathogen certainly hasn’t lost any virulence; both great signs for the future work we hope to do in this project.

“The next step is to transform isolates that represent each of the strains present in Australian cotton; 1A, 2A and 4B, as well as isolates within these strains that differ in virulence.

“From here, we can begin to deepen our understanding of the pathological differences between these strains by observing the way they enter, colonise and reproduce in a cotton host, to find answers for disease management options.

“The Panama 4 disease study using this technique determined that dying leaves of infected plants were heavily loaded with disease inoculum, and therefore management practices were implemented to remove infected leaf material, instead of assisting the disease cycle by leaving it in the fields.”

This article appears in the Autumn 2019 edition of CRDC's Spotlight magazine.