Molecular Pathology

Dr. Linda J. Harris, Study Leader

Objective

To develop new strategies for disease resistance in the mandated crops of the Eastern Cereal and Oilseed Research Centre by -

• increasing basic knowledge of the plant/pathogen interaction,
• characterizing, modifying and transferring genes encoding traits for resistance to Fusarium infection in corn and wheat, and white mold in soybeans.

Rationale

The molecular and cell biology of interactions between the host plant and Fusarium and Sclerotinia fungal pathogens are being studied to identify the factors that facilitate the disease infection and to understand the plant's disease response. The knowledge will be used to design molecular genetic strategies to enhance plant resistance and immunity in corn, wheat and soybeans.

The Ontario corn and wheat industries have indicated that research to develop acceptable levels of resistance to Fusarium graminearum (head blight in wheat/barley and ear mold in corn) is a high priority. Concerns are that -

• the disease not only affects yield but also leaves mycotoxin residues in the crop which renders the crop worthless,
• the adoption of no-till farming practices potentially creates a higher level of inoculum for fungal diseases,
• the development of cultivars which are more disease resistant will encourage the use of no-till practices, thereby enhancing environmental sustainability.

Recent farmgate losses in Ontario wheat from infection by Fusarium amounted to over $100 million. Major losses were also recorded for corn. While germplasm which exhibits lower levels of susceptibility to Fusarium have been identified in corn and wheat, the underlying mechanisms and long term stability are unknown. Molecular technology is being used in this study as it offers an opportunity to understand the current resistance mechanisms and to introduce novel Fusarium resistance into both corn and wheat through gene modification and transfer. The technology developed at ECORC for Ontario corn and wheat is also applicable to western Canadian wheats and barley.

White mold disease of soybean, caused by the fungus Sclerotinia sclerotiorum, results in annual crop losses of about $6 million. A gene for the enzyme, oxalate oxidase, has been transformed into soybean and has shown resistance to white mold in greenhouse assays and field trials. Understanding the mode of action of oxalate oxidase in conferring resistance to white mold will allow the development of alternate strategies for pathogen resistance.