Wheat researchers have made advances in the genetics behind resistance to Septoria leaf blotch, spurring the development of new wheat varieties to help growers reduce losses from the common disease.

"We have identified sources of high-level resistance to Septoria leaf blotch and investigated the inheritance of this resistance," says Dr. Anita Brûlé-Babel, Professor of Plant Science and wheat breeder at the University of Manitoba (U of M). "This will allow wheat breeders in Western Canada to develop new wheat varieties that carry this resistance, providing a sustainable solution to wheat growers."

Septoria leaf blotch has been one of southern Manitoba's major leaf diseases since it appeared in the area in the 1990-1991 crop year. The emergence of the stubble-borne disease is attributed in part to the adoption of conservation management practices that leave crop residues on the soil surface.

"Residue-borne diseases are responsible for millions of dollars in lost revenue annually for our wheat industry," says Brûlé-Babel. "The most economical method of reducing these losses is to incorporate genetic resistance into commercial wheat varieties - that's what ultimately will be the payoff of the research progress we're seeing today." New varieties carrying the resistance are expected over the next three to five years.

The progress was driven in part by the investment of western wheat farmers through the Wheat Check-off Fund, administered by Western Grains Research Foundation (WGRF). The Check-off supports breeding-related tan spot research at the U of M. These farmer dollars drew matching funding from the Natural Sciences and Engineering Research Council of Canada (NSERC), which has been used to support the Septoria leaf blotch project.

"Because WGRF is considered an industry partner, my collaborator, Dr. Lakhdar Lamari, and I were able to apply through NSERC to match those dollars for other industry-oriented research," says Brûlé-Babel. Through NSERC, the university has matched nearly all Check-off funds it has received since 1995.

The Septoria leaf blotch project included two main components, conducted by graduate students. As part of his PhD work, Curt McCartney, with the additional collaboration of Dr. Daryl Somers at the Agriculture and Agri-Food Canada Cereal Research Centre, identified the chromosome location of a resistance gene that has been labelled "Stb7." Researchers also identified three "molecular markers" that signal the presence of this resistance.

Molecular markers are pieces of DNA that repeated analysis shows are closely linked to the presence of genes that control a specific trait. The advantage is that these markers are much easier to identify than the genes themselves, making them a powerful selection tool for breeders.

"As a result of this work, we have made great progress in understanding the genetics of resistance and how to incorporate it into commercial cultivars," says Brûlé-Babel. "Developing those cultivars and getting them out to farmers is now just a matter of time and resources."

In the second component of the project, MSc. student Ardelle Grieger investigated and described the pathogen race profile in Western Canada of the causal agent of Septoria leaf blotch and documented the differences in the infection process between resistant and susceptible wheat genotypes.

"This component helped us learn more about the status of the disease in the field, and how it infects the plant. This will help us to design the best solutions," says Brûlé-Babel. "The first step was to identify and characterize the different isolates of the pathogen in the field, and to look at genetic variation, difference in virulence patterns, and the infection process."

The producer-funded Wheat Check-off Fund, administered by WGRF, allocates more than $3 million annually to wheat breeding programs in Western Canada.