Page 218 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

from all lesion sizes whereas there were 63% more fast-growing species associated with large lesions as
compared to medium-sized lesions. A maximum of three Pythium species were isolated from a single
lesion, with these lesions exhibiting large to very large sizes. In conclusion, seven Pythium species
associated with cavity spot lesions, with P. sulcatum being the most predominant.

*[P30] UNVEILING THE COMPLETE GENOME OF THE CLUBROOT PATHOGEN. Muhammad
Asim Javed , Soham Mukhopadhyay , Éric Normandeau , Anne-Sophie Brochu , and Edel Pérez-
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López . Départment de Phytologie, Université Laval, Québec (Québec), Canada, G1V 0A6; Centre de
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recherche et d’innovation sur les végétaux (CRIV), Université Laval, Québec (Québec), Canada, G1V
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0A6; Institute de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec (Québec),
Canada, G1V 0A6; L’Institute EDS, Université Laval, Québec (Québec), Canada, G1V 0A6; and Centre
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SÈVE Université de Sherbrooke, Sherbrooke (Québec), Canada, J1K 2R1
Correspondence to: edel.perez-lopez@fsaa.ulaval.ca

Plasmodiophora brassicae is the causal agent of clubroot disease of cruciferous plants and a major threat
to the rapeseed (Brassica napus) and brassica vegetable industry worldwide. The clubroot pathogen has
been reported in more than 80 countries, causing economic losses of hundreds of millions every year. In
Canada, despite the identification and characterization of more than 40 clubroot pathotypes that pose a
significant threat to the canola industry, high-quality assembled, and annotated genomes for Canadian
isolates remain unavailable. Moreover, very little is known about the molecular strategies this pathogen
employs to induce the characteristic clubs in the roots of susceptible hosts during infection or the
mechanisms it uses to overcome genetic resistance. Therefore, complete, and high-quality genomes are
essential to understand the evolution of plant pathogens and the strategies they use to overcome genetic
resistance. In this presentation we introduce the first telomere-to-telomere genome assembly of P.
brassicae (pathotype Pb3A), and the first complete genome for a member of the supergroup Rhizaria. We
produced a 25.3 Mb assembly comprising 20 chromosomes, with an N50 of 1.37 Mb and significantly
improved all genome assembly statistics. Using available transcriptomic data and protein evidence, we
annotated the Pb3A genome, identifying 10,521 protein-coding gene models – the highest number in
existing genomic resources for this pathogen. Furthermore, we have identified 200 additional candidate
effector proteins beyond the lists generated from previously available genomes, potentially critical for
pathogen virulence. By comparing the long-read genome assemblies of the European genome (e3) and
Pb3A we identified structural variations between the two pathotypes. Finally, our results will enable more
robust and cost-effective analyses in population and comparative genomics and help to uncover structural
variations among genomes of different clubroot pathogen isolates or pathotypes that can be linked to
pathogenicity or evolution.

[P31] SOYBEAN ROOT DISEASES IN MANITOBA: HISTORY, MONITORING, PREVALENCE, AND
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CROP ROTATION EFFECTS. Yong Min Kim , Ahmed Abdelmagid , Owen Wally , Ramona Mohr , and
Debra McLaren (ret’d). Brandon Research and Development Centre, Agriculture and Agri-Food
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Canada, 2701 Grand Valley Rd, Brandon, MB, Canada, R7C 5Y3; Morden Research and Development
Centre, Agriculture and Agri-Food Canada, 101 Route 100, Morden, MB, Canada, R6M 1Y5; and Harrow
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Research and Development Centre, Agriculture and Agri-Food Canada, 2585 Essex County Rd 20,
Harrow, ON, Canada, N0R 1G0
Correspondence to: yongmin.kim@agr.gc.ca

Soybeans were first cultivated in Manitoba at the Experimental Farm in Brandon in 1898 as a forage crop,
following their initial introduction to Canada in 1893 and to the USA in 1851. The first documented
occurrence of root rot in soybeans caused by Fusarium sp. in Manitoba was recorded in 1924. Although
Phytophthora root rot was first observed in the USA in 1948, it was not until 2011 that Phytophthora root
rot was first detected in Manitoba. The province’s first soybean production statistics were recorded in
1942 with 2,510 acres cultivated, but significant commercial production of soybeans did not occur until the
early 2000s in Manitoba. In 2012, Manitoba surpassed Quebec to become Canada's second-largest
soybean producer after Ontario, reaching a peak of 2.3 million seeded acres in 2017. This increase was
largely attributed to the development of early-maturing, high-yielding varieties. With the expansion of
soybean cultivation in Manitoba, Agriculture and Agri-Food Canada initiated extensive root disease
surveillance in 2012. The annual root disease survey aimed to assess the prevalence and distribution of
soilborne pathogens affecting soybean root health and productivity across the province’s major soybean-

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