How your farm samples help improve varietal resistance

Research programs are often asking for growers and advisors to send in disease samples to assist in their research, but how does this lead to more profitable varieties for you? How are your samples used by researchers to ensure new varieties have improved disease resistance?

Stop the Spot

Stop the Spot is an initiative by the GRDC and Curtin University-supported Centre for Crop and Disease Management (CCDM), which calls on growers and advisors to send in samples of yellow spot disease.

With these samples, CCDM’s yellow spot research program aims to provide wheat breeders with tools to breed more resistant varieties. When samples are received the researchers extract DNA from the infected leaf to determine the presence of the yellow spot pathogen. They are then able to grow the pathogen out to select a pure strain of the fungus. The researchers then look for the genes in this pure strain which encode effectors (host-selective toxins). In simple terms – those genes which allow that strain of yellow spot to attack a wheat plant.

Once they find an effector, the researchers clone it from the genome. The protein of the gene is expressed and produced on a large scale and purified ready for the breeders. The breeders will receive the bulked up effector protein, and can then infiltrate the solution into their wheat seedlings. Within days, breeders will be able to see if their wheat lines are sensitive to the toxin, and if they are, they can discard them, only keeping the resistant varieties in their programs.

More information on what happens to your sample is available on the Stop the Spot website.

Barley Powdery Mildew

CCDM’s barley powdery mildew program uses samples from growers and advisors to keep better track of the disease and watch for the development of new pathotypes. They also ensure resistant barley varieties are retaining their resistance, and if not, they communicate any breakdowns out to growers.

When a sample arrives at the CCDM laboratories, researchers will take a sample of the culture from the leaf, and grow it on a susceptible barley variety, to ensure the sample is healthy.

Meanwhile, researchers will also grow Pallas barley lines. Pallas barley lines consist of about 20 different barley cultivars that are specifically bred to each hold a different resistance gene. Leaves of these barley lines are cut and placed onto agar plates, ready for powdery mildew infection.

As a final step, researchers will then infect the Pallas barley lines with the recently sent in sample of powdery mildew and score the level of infection. If the powdery mildew survives, then they know there has been a breakdown in resistance to barley varieties that hold that resistance gene.

Monitoring genetic resistance in barley to powdery mildew allows growers to feel assured that the variety they are growing will hold up its defence against the pathogen, and if not, there’s a research team ready to confirm the genetic breakdown.

Examples:

Megan Meates, CCDM (08 9266 4818, 0437 538 541) to start – CCDM does yellowspot and net blotch and powdery mildew https://www.grdc.com.au/Media-Centre/Media-News/West/2015/07/Watch-out-for-powdery-mildew-on-resistant-varieties

Ascochyta monitoring in pulses

Jenny Davidson SARDI

Ascochyta monitoring at SARDI (Curtin Asco population monitoring project), collecting isolates and doing phenotyping

Rust at Syd Uni

background https://www.grdc.com.au/Media-Centre/Media-News/North/2015/07/Bust-the-rust-in-wheat-this-season

http://sydney.edu.au/agriculture/plant_breeding_institute/cereal_rust/pathogenicity_surveys.shtml

http://sydney.edu.au/agriculture/documents/pbi/cereal_rust_report_2016_14_3.pdf

despatch forms http://sydney.edu.au/agriculture/plant_breeding_institute/cereal_rust/reports_forms.shtml#df

 

When should I send in a disease sample?

  • On resistant varieties
  • When fungicide isn’t doing the job as well as you think it should.

List of relevant disease samples and contacts

 

Disease Relevant Program Contact Details Further information link
Powdery mildew on barley or wheat CCDM powdery mildew and fungicide resistance program ccdm@curtin.edu.au http://ccdm.com.au/farm-management-resources/how-to-send-us-samples/
Yellow Spot Stop the Spot info@stopthespot.com.au http://stopthespot.com.au/get-involved/
Ascochyta SARDI Jenny Davidson?
Cereal rust Australian Cereal Rust Control Program
Sclerotinia stem rot on canola CCDM ccdm@curtin.edu.au http://ccdm.com.au/farm-management-resources/how-to-send-us-samples/
Net blotch on barley CCDM ccdm@curtin.edu.au http://ccdm.com.au/farm-management-resources/how-to-send-us-samples/

 

 

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