Page 204 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

up to 20 years, making the disease difficult to control. The current disease management strategy is to
grow clubroot-resistant (CR) cultivars in rotations. However, the existing CR varieties carry race-specific,
dominant resistant (R) genes that can be broken down with a shift in the pathogen population and
continuous cropping. In this study, we screened Arabidopsis mutant collection and identified a gene that
when modified confers robust tolerance to clubroot and tentatively named it CRT1; loss of function in
CRT1 resulted in tolerance or even immunity against the clubroot disease. Furthermore, the Arabidopsis
CRT1 mutant showed enhanced resistance to multiple clubroot pathotypes, indicating that the tolerance
is race/pathotype-independent. Two orthologous CRT1 genes were identified in B. napus and both were
targeted through the CRISPR/Cas9 gene editing. In total, 203 independent transformation lines were
obtained and 50 T0 plants were genotyped to determine editing status. Thus far, we have identified one
line exhibiting homozygous mutations in both genes, another line with heterozygous mutations in both
genes, and several additional lines with mutations in only a single gene. Clubroot disease test on the
homozygous double mutant plants has demonstrated promising results of tolerance. Considering the
broad-spectrum tolerance conferred by this gene and its potential for resilience against tolerance
breakdown, incorporating it into elite or commercial canola varieties could have significant potential for
developing durable tolerant cultivars by the canola industry.

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