Australian breeders to benefit from outcomes of international collaboration

Author: | Date: 21 Aug 2018

Image of CCDM’s Kar-Chun Tan
CCDM’s Kar-Chun Tan says new findings take researchers a step closer to cloning an elusive wheat gene, which would facilitate more rigorous research into septoria nodorum blotch (SNB) and broaden understanding of the host-pathogen interactions that cause it. Photo by CCDM.

Australian cereal breeders are set to benefit from new research being undertaken by the Centre for Crop and Disease Management (CCDM), as part of an international collaboration looking at septoria nodorum blotch (SNB) in wheat.

The collaboration between United Kingdom-based plant science institute NIAB (the National Institute of Agricultural Botany) and the CCDM has revealed new information about the sensitivity of European elite wheat lines to the SNB-causing pathogen Parastagonospora nodorum (P. nodorum), which could prove useful for Australian breeders wanting to remove susceptibility to the disease from their cultivars.

The study identified 10 significant genetic markers for the disease and worked to validate them across 480 predominantly UK winter wheat varieties.

Researchers from the CCDM – a co-investment by Curtin University and the Grains Research and Development Corporation (GRDC) – are now also validating these markers on major Australian wheat cultivars.

“This research is part of the ongoing work of the CCDM to break down the host-pathogen interactions that cause SNB in wheat,” CCDM’s Kar-Chun Tan said.

“These studies provide valuable information for us to share with Australian breeders so they can screen for disease-resistant varieties, target their breeding and eliminate host sensitivity to diseases on an effector-by-effector basis.”

SNB is a disease of significant economic importance in many wheat-growing regions around the world. It causes an estimated $108 million a year in yield loss to the Australian wheat industry (Murray and Brennan 2009).

The visible symptoms of this disease include the formation of lesions on and discolouration of the leaf tissue. These lesions reduce the amount of leaf surface capable of photosynthesis, limiting the crop’s growth.

To successfully mount an infection, the SNB-causing pathogensecretes effectors to cause tissue death on wheat varieties that carry a particular genetic background.

Tox3 is a major effector produced by it, and sensitivity to the effector in wheat is linked to the presence of the Snn3 gene, which has not yet been identified. This study could prove a game-changer in this respect, shedding new light on one of SNB’s most significant and elusive genes.

“The study was able to identify 10 significant genetic markers that are linked to Snn3. This includes one (Excalibur_c47452_183) which was validated as a reliable diagnostic tool that can be used to differentiate wheat varieties with and without the Snn3 gene,” Dr Tan said.

“It is imperative that we use this technology to identify wheat varieties that lack Snn3 so that SNB resistance can be enhanced and, in order to do so, CCDM researchers are now testing the reliability of these newfound markers on Australian wheat cultivars.

“These findings take us a step closer to cloning this elusive wheat gene, which would allow for more rigorous research into SNB and broaden our understanding of the host-pathogen interactions that cause it.”

The study was carried out by NIAB PhD student Rowena Downie and led by Dr James Cockram, in  collaboration with CCDM’s Professor Richard Oliver and Dr Tan.

The journal Frontiers in Plant Science has published the study findings, including the validated genetic marker linked to Snn3 (Excalibur_c47452_183), in Assessing European wheat sensitivities to Parastagonospora nodorum necrotrophic effectors and fine-mapping the Snn3-B1 locus conferring sensitivity to the effector SnTox3. The full article can be found at http://bit.ly/2LSpr7n

If you would like more detail on this research please contact Dr Tan at kar-chun.tan@curtin.edu.au.

Contact Details

Contact

Carole Kerr, CCDM
0437 538 541
carole.kerr@curtin.edu.au

Natalie Lee, GRDC
0427 189 827
natalie.lee@grdc.com.au

GRDC Project code: CUR00023