Wheat Take-all bioassays

Wheat Take-all bioassays

This assay is used to determine whether Streptomyces strains are able to produce antifungal compounds that inhibit the wheat root pathogen Gaeumannomyces tritici, which is causes wheat take-all disease.

This assay usually takes 14 days, but it may take longer as the time taken for the plug to establish in the assay plate may vary.

Preparation and reagents needed

• 33ml Potato Dextrose Agar (PDA) plates.
• Streptomyces spores in 20% glycerol.
• Actively growing plate of Gaeumannomyces tritici.
• Glass Pasteur pipette or sterile P1000 pipette tips

Instructions

1. Inoculate PDA plates in triplicate by spotting 5μl of Streptomyces spores about a third of the way into a plate of PDA.
2. Allow cultures to grow for 7 days at 30°.
3. Using a flame sterilized Pasteur pipette or P1000 pipette tip, remove a plug of agar about a third of the way into the plate opposite the Streptomyces colony. Sterile toothpicks can be used to assist removal of the agar plug.
4. Remove a plug of agar from actively growing Gaeumannomyces tritici and transfer it to the Streptomyces plate. It is useful to transfer plugs in triplicate to blank PDA plates as a negative control
5. Allow plates to grow at 22° for 7 days. The time taken for the plug to establish in the assay plate may vary, so may need to be grown for longer.