VG07010 Systemic aquired resistance

Systemic acquired resistance (SAR) is a broad, physiological immunity in plants that can be triggered by treatment with a biological or chemical agent. It is the plant equivalent of an immune response in humans.

This project seeks to find ways to trigger systemic acquired resistance in vegetable brassicas to increase the ability of treated plants to ‘defend themselves’ against clubroot and white blister.


Arati Agarwal

Caroline Donald

Robert Faggian

Ian Porter

Systemic Aquired Resistance - SAR
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Brief :

Molecular and genetic studies were conducted using Arabidopsis (a weedy relative of vegetable brassicas suited to laboratory use) and Plasmodiophora brassicae (the cause of clubroot).

These studies showed that :

  • A number of genes involved in plant defence are up or down regulated four days after inoculation with P. brassicae.
  • Many of these genes are part of important signal transduction pathways such as the salicylic acid and jasmonic acid pathways.
  • Increasing salicylic acid by induction of the salicylic acid pathway may suppress clubroot disease.

The ability of salicylic acid to induce a SAR response in Arabidopsis and broccoli (cv Greenbelt), and the effectiveness of this response against clubroot was studied under controlled conditions.

Clubroot disease was strongly suppressed in salicylic acid treated Arabidopsis plants.

Changes in the expression of key plant defence genes are being measured.

There was no visible effect on clubroot development in broccoli at the rates used.

It is possible that higher rates or longer contact times may be required for broccoli roots which are much thicker than Arabidopsis.

Acknowledgments :

Funding was provided by Australian vegetable growers (through the R & D levy) and the Department of Primary Industries, Victoria. The Australian Government provides matched funding for all HAL’s R&D activities.

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