Characterization of defense genes underlying quantitative resistance loci (QRL) to sclerotinia stem rot in Asian Brassica napus and transfer of resistance to Canadian spring-type canola

Project Summary

Overview

Although sclerotinia resistance is a very rare trait, researchers have been able to generate B. napus lines with high levels of sclerotinia resistance. Canola breeders are interested in developing new canola varieties with sclerotinia resistance and some have requested seed of the resistant lines, molecular markers linked to the resistant trait, and sclerotinia isolates for screening of breeding lines. These lines will enable plant breeders to develop canola varieties with a high level of sclerotinia resistance, which will reduce the need for fungicide application, resulting in economic benefit to growers and also safeguarding growers, consumers and the environment.

Researchers have also developed a stem test protocol for testing canola for resistance to S. sclerotiorum. In 2016, after five years of evaluation by nine collaborators, the protocol was approved by the Western Canada Canola/Rapeseed Recommending Committee (WCC/RRC) as a standard for assessing sclerotinia resistance of lines submitted to co-op tests. Canola breeders and an increasing number of scientists in other countries including Australia and India are also using this stem test protocol. By the end of Dr. Buchwaldt’s project, it is expected that the first canola lines with improved sclerotinia resistance from the program will be available for licensing. This resistance is expected to be long lasting, since it relies on several defense genes that are not easily overcome by changes in the pathogen population.

Purpose:

(1) To identify molecular markers linked to sclerotinia resistance and identification of underlying defense genes.

(2) to transfer sclerotinia resistance to elite open-pollinated spring-type canola.

Results

This study generated new knowledge on individual defense genes against S. sclerotiorum and on SNP and SSR markers that can be used in marker-assisted selection. A ‘stem test’ to screen B. napus plants for sclerotinia resistance was also developed and accepted by the canola industry, including adoption by the Western Canadian Canola/ Rapeseed Recommending Committee (WCC/RRC). Work was started on transferring sclerotinia resistance into an elite AAFC line, and new funding will be sought to continue the project in collaboration with breeding companies.

Related publication

Dr. Buchwaldt’s continual sclerotinia research (with additional scientists) has also produced this 2022 publication:

Sources of genomic diversity in the self-fertile plant pathogen, Sclerotinia sclerotiorum, and consequences for resistance breeding

This publication demonstrates that sclerotinia isolates are more closely related within Manitoba, but not closely related in Alberta, while Saskatchewan isolates fall between these two opposites. This is likely due to the accumulated effect of more canola and other host crops in rotation, and higher rainfall in more growing seasons in Manitoba than in the two other provinces.