Resistance to Sclerotinia sclerotiorum necrosis inducing proteins in canola

Project Summary

Overview

Sclerotinia sclerotiorum causes disease on over 400 plant species; however, the level of resistance in virtually all major crops, in particular canola, is insufficient. Chemical control of the pathogen using fungicides is the only means currently available, but success depends on accurate prediction of pathogen load within the field and future weather conditions to ensure that coverage and timing of fungicide application coincides with release of fungal spores. At present, the only sources for Canadian breeders are winter-type lines from parts of Asia and the middle-East with partial resistance to stem rot resulting from the cumulative effects of several genes. This has made incorporation of the trait into spring-type canola difficult and has limited the development of stem rot resistant varieties by private sector canola breeders.

The best solution for Canadian farmers is to develop spring-type varieties with one or a few highly effective and robust stem rot resistance genes. This project contributes to this effort by providing both a more complete understanding of how the fungus causes stem rot in canola, and a highly targeted means to identify stem rot resistant lines. The focus is on how S. sclerotiorum causes the most noticeable and damaging aspect of disease in canola, namely, the necrotic lesions on the stem that lead to lodging and crop loss.

Purpose

(1) To identify proteins secreted by S. sclerotiorum that cause or contribute to necrosis.

(2) To develop a method to screen B. napus lines for resistance to their effects.

Results

In this project, several new Sclerotinia sclerotiorum proteins, which cause the necrotic lesions associated with stem rot disease, were discovered. The proteins are now under study and tools are being developed to screen collections of B. napus lines for resistance to their effects.

This project has greatly improved the understanding of S. sclerotiorum disease as the researchers catalogued for the first time the entire suite of genes deployed during each stage of the infection on canola. This project also contributed to an international consortium of Australian, U.S., European and Canadian researchers to sequence the S. sclerotiorum genome, which was published and deposited in a public database.

This research contributed to an international consortium that sequenced the S. sclerotiorum genome, which is now serving as a reference for a new international initiative to sequence the genomes a global collection of S. sclerotiorum isolates from a multitude of crops. The researchers catalogued the entire suite of genes expressed during each stage of the infection of canola that has led to a much better understanding of how S. sclerotiorum causes disease. They also identified several new proteins that are secreted by S. sclerotiorum that cause necrosis and began developing tools that will use necrosis proteins to screen B. napus collections for lines that are more tolerant of or resistant to their effects.