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.
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 :
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.
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.