Page 123 - Plant Canada 2024 Proceeding

PLANT CANADA 2024

*[O43] IDENTIFICATION OF NOVEL AND DIVERSE MYCOVIRUSES IN THE PHYTOPATHOGENIC
1,2
1,2
FUNGUS, BOTRYTIS CINEREA. Sarah C. Drury , Naser Poursalavati , Peter Moffett , and Mamadou
2
Lamine Fall . Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food
2 1
Canada, 430 Boulevard Gouin, Saint-Jean-sur-Richelieu, QC J3B 3E6, Canada; and Centre SÈVE,
2
Département de Biologie, Université de Sherbrooke, 2500 Boulevard de l’Université, Sherbrooke, QC J1K
2R1, Canada
Correspondence to: sarah.drury@agr.gc.ca

Botrytis cinerea is a necrotrophic fungal pathogen that causes significant economic losses to a wide
variety of crops. To date, over 100 mycoviruses have been reported in Botrytis spp., some of which
induce reduced virulence (hypovirulence). Hypovirulence-inducing mycoviruses can be used as biocontrol
agents, offering alternative methods to synthetic fungicides for managing B. cinerea. This research aimed
to explore the mycovirome of B. cinerea and identify potential hypovirulence-inducing mycoviruses. B.
cinerea isolates were collected from different horticultural crops in Quebec. Fitness and pathogenicity
criteria, including conidiation, radial growth, and morphotype, were evaluated. A double-stranded RNA
(dsRNA)-based extraction method was developed to sequence 42 low-performing and three higher
performing isolates. A customized bioinformatics workflow, Soil Virome Analysis Pipeline, was used for
analysis. Mycoviruses were detected in 44 out of 45 isolates. These mycoviruses belonged to 19 families
and to unclassified dsRNA, positive-strand RNA (+ssRNA), and negative-strand RNA (-ssRNA) genome
types, demonstrating that B. cinerea has an evolutionarily diverse mycovirome. Most mycoviruses had
+ssRNA and dsRNA genomes, and a small number had -ssRNA, single-stranded DNA, and reverse
transcriptase RNA genomes. Several mycovirus species positively and/or negatively co-occurred with
each other or with being in B. cinerea isolates collected from specific hosts. Additionally, 62 novel contigs
belonging to novel strains of mycovirus species were identified through RNA-dependent RNA polymerase
analysis and motif identification. Further, this method was used to identify four putative novel mycovirus
species belonging to Endornaviridae, Botybirnaviridae, Peribunyaviridae, and Bunyavirales taxa.
Hypovirulence-inducing mycoviruses including Botrytis cinerea mitovirus 1, Botrytis cinerea fusarivirus 1,
and Botrytis porri botybirnavirus 1 were also detected. This study provides valuable insights into the
taxonomy and diversity of mycoviruses in B. cinerea which will be useful for subsequent evaluations of
select mycoviruses as biocontrol agents.

*[O44] COLLECTION AND IDENTIFICATION OF PLASMODIOPHORA BRASSICAE PATHOTYPES
COLLECTED IN WESTERN CANADA OVER THE LAST TEN FIELD SEASONS (2014-2023). Emilee
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1
1
1
Storfie , Victor Manolii , Yoann Aigu , Michael Harding , Sheau-Fang Hwang , and Stephen Strelkov .
2
1
1 Department of Agriculture, Food, and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5,
Canada; and Crop Diversification Centre South, Alberta Agriculture and Irrigation, Brooks, AB T1R 1E6,
2
Canada
Correspondence to: strelkov@ualberta.ca

Canola (oilseed rape; Brassica napus) is the second-most important oilseed crop worldwide. In the
Canadian Prairies, canola production can be severely impacted by clubroot disease, caused by the
obligate soilborne parasite Plasmodiophora brassicae. Initially controlled by first-generation clubroot-
resistant (CR) canola cultivars, shifts in the virulence of P. brassicae populations have led to an
increasing number of resistance-breaking pathotypes. As this disease continues to spread and novel
pathotypes emerge on CR cultivars, it becomes increasingly important to collect field isolates with
clubroot symptoms for downstream pathotype characterization. During annual field surveys from 2021 to
2023, a total of 210 field isolates were collected: 198 in Alberta, eight in Saskatchewan, and four in
Manitoba. Each isolate represented one field and its pathotype designation was evaluated on the
Canadian Clubroot Differential (CCD) set. Thirty-one unique pathotypes were found across all tested
isolates, which included eight novel resistance-breaking pathotypes (1D, 1G, 3F, 3J, 5D, 6F, 8K, and 9G)
and one pathotype (1H) still controlled by first-generation clubroot resistance. Pathotypes 3A, 3D, and 3H
were identified at the highest frequencies among the field isolates assessed, and their geographic
distribution in Alberta was mapped. In an effort to refine the CCD set, an automated approach was
investigated to improve the accuracy and speed of pathotype designation, which is currently determined
manually. A meta-analysis of virulence patterns across isolates collected over the past 10 field seasons
(2014-2023) revealed over 50 unique pathotypes in western Canada, with more than half confirmed as
resistance breaking. The majority of these pathotypes are rare, identified at frequencies of less than 2%,

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