Sampling for Candidatus Liberibacter solanacearum (CLso) (PT19001)

What was it all about?

The Candidatus Liberibacter solanacearum (CLso) bacterium poses a significant threat to the Australian potato industry, being associated with ‘zebra chip’ disease and able to be carried by the tomato potato psyllid. This short project, which ran from 2019 to 2020, developed and validated sample collection and preservation protocols, and the associated sampling kits for CLso testing in potato tubers.  

This investment to prepare and protect the Australian industry follows previous levy-funded projects Diagnostic capability to detect Candidatus Liberibacter solanacearum (CLso) (PT17000) and Developing and implementing a high throughput diagnostic test for Candidatus Liberibacter solanacearum (CLso) (PT17000).

Tuber cores were shown to be a superior alternative to tuber slices for CLso diagnosis. Tuber tissues and associated pathogen DNA can be efficiently preserved using calcium carbonate-based desiccant for downstream DNA extraction and disease detection.

A customised sampling tool to collect tuber samples was produced. The tool standardises sample size and streamlines collection. A prototype was tested by growers and, following feedback and minor adjustments, 300 coring tips were produced.

A field sampling protocol has been defined that is based on high-throughput diagnostic testing and sampling recommendations, using the kit developed by this project.

The sampling kit is designed for collecting six composites of 50 cores per paddock/seed lot. It includes illustrated instructions, a coring device, and six zip lock bags each containing a 125g desiccant pouch. The bags are barcoded to facilitate sample tracking within the South Australian Research and Development Institute’s laboratory information management system.

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See video on Sampling potato for CLso the cause of Zebra chip disease.