REDUCING the impact of the wheat disease Septoria tritici blotch (STB) has become a focal point for the Grains Research and Development Corporation (GRDC).
STB is a persistent issue for wheat growers in the high and medium rainfall zones of the northern and southern grain growing regions, and if left unmanaged can reduce yields by up to 50 per cent.
GRDC has invested in three projects - identifying genes for STB resistance, testing gene combinations for STB resistance and understanding the cause of STB.
Traditional control by fungicides is estimated to cost the industry $121 million per year, however resistance to some common fungicides including triazoles and strobilurin used to control STB is evolving.
Joining forces with the New South Wales Department of Primary Industries (NSW DPI) and the Australian National University (ANU), the GRDC will invest $8m over five years to identify novel STB resistance genes to incorporate into new Australian wheat varieties.
GRDC genetic technologies officer Prameela Vanambathina said they were approaching the STB problem from three different angles.
"We are seeking to identify novel resistance genes, optimal combinations of adult plant resistance genes and understand plant pathogen interactions," Ms Vanambathina said.
"We hope these three investments will provide tools and knowledge essential to reduce the impact of the disease for Australian graingrowers.
"Most wheat varieties are susceptible to STB, leading to increased use of fungicides to control the disease, but there's a growing fungicide resistance problem, and the identification of new seed sources resistant to Australian pathotypes is crucial."
Identifying genes for STB resistance
The first of the three projects aims to discover and transfer novel adult plant resistance genes for STB resistance into wheat breeding programs.
Led by Dr Andrew Milgate, from NSW DPI, it aims to identify novel genetic resources that are resistant to STB under Australian environments.
The investment's objectives include identifying and characterising novel sources of adult plant resistance from international and Australian germplasm pools, validating these genes and transferring the genetic potential into elite Australian wheat lines.
Testing gene combinations for STB resistance
"Previous GRDC investment with NSW DPI and ANU has already identified genes that can contribute to adult plant resistance to STB," Ms Vanambathina said.
The focus of this project is on testing optimal combinations of these genes to identify the best ones, and a smaller number of genes for stable adult plant resistance.
Dr Milgate said this partnership would see different combinations of resistance genes, previously identified by NSW DPI researchers in Wagga Wagga, to be bred into wheat varieties.
Combining these high-quality genes together provides added, more stable protection and ensures the genes continue to be effective against STB, which can evolve new virulence rapidly.
"For breeders to efficiently use the resistance genes we also need to provide them with molecular makers that can be used to track the genes in their breeding programs," Dr Milgate said.
Having molecular markers makes it much faster and more accurate to bred wheat with the desirable resistance genes, meaning new wheat with improved STB resistance can be delivered to growers sooner.
"This is another important component of the projects - to find where the genes are located on the wheat genome and what DNA sequence changes can be used as markers," he said.
Understanding the cause of STB
ANU professor Peter Solomon said the university was pleased to continue its long-standing partnership with GRDC to tackle diseases that affect the viability and productivity of wheat in the third STB project.
"Despite the impact that STB has on growers, disease and genetic resistance remains poorly understood," professor Solomon said.
"This investment by GRDC will enable us to work with colleagues at Birmingham University in the UK to dissect the interaction between key pathogen proteins responsible for virulence and their corresponding host resistance genes in progressing disease.
"The outcomes will significantly advance our understanding of how the fungus Zymoseptoria tritici causes STB, and the data generated will be used to develop an approach for screening disease-resistant cultivars."
ANU professor Peter Solomon said the university was pleased to continue its long-standing partnership with GRDC to tackle diseases that affect the viability and productivity of wheat in the third STB project.
"Despite the impact that STB has on growers, disease and genetic resistance remains poorly understood," professor Solomon said.
"This investment by GRDC will enable us to work with colleagues at Birmingham University in the UK to dissect the interaction between key pathogen proteins responsible for virulence and their corresponding host resistance genes in progressing disease.
"The outcomes will significantly advance our understanding of how the fungus Zymoseptoria tritici causes STB, and the data generated will be used to develop an approach for screening disease-resistant cultivars."
