Sources of Genetic Resistance to Wheat Smut Identified in Australia

From left to right, CCDM project leader Associate Professor Kar-Chun Tan, CCDM Associate Professor Simon Ellwood, Intergrain Chief Operating Officer Daniel Mullan, and CCDM PhD student Ancy Tony in a conviron chamber observing wheat powdery mildew.
Photo: Lisa Smith, CCDM.

Researchers at the Centre for Crop and Disease Management (CCDM) at Curtin University have identified promising sources of resistance that could be utilised in breeding programmes.

Whilst wheat powdery mildew resistant to fungicides has been detected across much of Australia, researchers at the Centre for Crop and Disease Management (CCDM) have identified genetic resistance sources that could help breeders develop more resilient wheat varieties.

A growing problem for growers

This fungal disease, caused by the pathogen Blumeria graminis, has become a significant problem for growers in recent years. The rapid spread of fungicide resistance across most Australian states is significantly limiting options for controlling the disease.

The collaboration between the CCDM and the Australian seed breeding company InterGrain focused on the nationwide diversity of these pathogens and the identification of potential sources of resistance genes. The study’s findings also formed the basis for a new project being carried out at the CCDM, jointly funded by the Grains Research and Development Corporation (GRDC) and Curtin University. As part of the project, the suitability of the identified resistance sources for use in future wheat breeding programmes will be assessed.

The research was published in the journal *Crop & Pasture Science* by PhD student Ancy Tony.

Wheat powdery mildew isolates collected from different regions of Australia were tested against 24 wheat lines carrying known powdery mildew resistance genes. Tony noted that this method allowed for an assessment not only of the disease’s nationwide diversity but also of which resistance genes retained their effectiveness.

According to Tony, the pathogen population is not dominated by a single race but exhibits significant variation. This means that reliance on a single resistance gene is not sufficient for disease control.

The most promising finding of the study was the identification of effective resistance in wheat lines that may contain additional resistance genes that breeders could utilise. Tony stated that the Khapli and Tabasco lines exhibited high resistance against all isolates of the disease and are therefore valuable sources of resistance for breeders.

Both lines carry previously identified resistance genes. CCDM researchers, however, believe that these lines may harbour additional, as yet unidentified genes. It is anticipated that combining these genes (pyramiding) could provide long-lasting resistance.

In addition, three European-origin varieties also showed promising resistance against Australian isolates. Tony noted that these varieties may possess as yet unexamined, more durable and broad-spectrum resistance.

The aim is to reduce dependence on fungicides

CCDM Project Leader Associate Professor Dr Kar-Chun Tan said the project aims to enhance wheat’s resistance by understanding the disease, thereby reducing the sector’s reliance on fungicide applications. Tan emphasised that the best way to prolong the effectiveness of fungicides is to breed varieties containing multiple resistance genes, and highlighted the urgency of working with breeders to offer farmers better options.

Tan explained that the project would identify genes effective against wheat powdery mildew and demonstrate how these genes could be combined to provide more robust resistance. Noting that the project is built upon CCDM’s expertise in the areas of Cereal Diseases and Fungicide Resistance, combined with the collective expertise of national and international partners, Tan said that bringing these resources together provides a strong foundation for finding a solution to the problem.

CCDM Director Prof. Dr Mark Gibberd noted that the collaborative work carried out with InterGrain and its evolution into a new research project highlights the value of sector partnerships in research. Gibberd noted that the study had identified several promising sources of resistance against wheat powdery mildew and that the findings provided a strong foundation for the next phase of research.

Gibberd emphasised that by collaborating with breeding companies and involving them in the research process, it was possible to ensure that the research produced meaningful results for the Australian grain sector. Gibberd stated that direct industry-research partnerships bridge the gap between research and application, and that the research is shaped according to the sector’s needs, adding that this enhances the potential for creating an impact for Australian growers.

The CCDM operates as a national research centre jointly supported by the GRDC and Curtin University.