Page 206 - PC2019 Program & Proceedings

PLANT CANADA 2019

S197. The prevalence and diversity of Fusarium species causing Fusarium Head Blight on oat in
Manitoba
*1
2
2
1
Tabassum, M. ; M. Banik ; M. Beyene ; F. Daayf ; X. Wang
3
1 University of Manitoba
2 Agriculture and Agri-Food Canada
3 Morden Research and Development Centre
Fusarium head blight (FHB), a devastating fungal disease caused by Fusarium spp., can lead to dramatic
yield loss and mycotoxin contamination in commercial grain production. Trichothecenes of type-A (T-2
and HT-2) and type-B (DON and NIV) are the common mycotoxins produced by Fusarium pathogens
affecting small grain cereals. Oat is a common crop grown for both feed and food in Canada. Recent
research has indicated that FHB has become very common on oat in western Canada. Nevertheless, the
impact and severity of FHB on Canadian oat production is not very clear. In this study, we investigated
the prevalence and diversity of Fusarium species in 168 oat samples collected from commercial fields in
Manitoba from 2016 to 2018 through morphological, conventional PCR and qPCR analysis. A complex
of Fusarium species, including F. graminearum, F. poae, F. avenaceum, and F. sporotrichioides are
found in these oat samples and F. poae is the most predominant, followed by F. graminearum and F.
sporotrichioides. The level of mycotoxins in these samples are analyzed usingLC-MS/MS method. The
correlation analysis between Fusarium DNA and mycotoxin level indicates that F. poae, F. graminearum,
and F. sporotrichioides are the main contributors of mycotoxins in oat samples. The phylogenetic
analysis of 160 F. poae isolates, using ELF1-α, TRI1, and TRI8, is currently in process.

Mourita Tabassum (tabassu3@myumanitoba.ca)

S198. ‘New’ pathotypes of Plasmodiophora brassicae in Canada are not new
*1
2
Sedaghatkish, A. ; B. Gossen ; M.R. McDonald
1
1 University of Guelph
2 Agriculture and Agri-Food Canada
Clubroot, caused by Plasmodiophora brassicae Wor., is an important disease of brassica crops. Clubroot
is generally managed using resistant cultivars, but new pathotypes are increasing rapidly on canola
(Brassica napus L.) in Canada. Whole-genome DNA sequences of P. brassicae collections from across
Canada were assessed to quantify genetic variation among populations. Many of the collections were also
pathotyped (Williams’ system + others) to assess the relatedness of new pathotypes to the previously
predominant pathotypes on canola. In total, 43 single-spore and field collections of P. brassicae from
Canada, the USA, and China were sequenced. The collections from Canada separated into four clades:
two primarily from canola on the Prairies and two primarily from other regions of Canada, but 3 of 4
clades contained multiple pathotypes from various hosts. The ‘new’ pathotypes from the Prairies
generally clustered together, separately from the previously predominant pathotypes on canola. At two
sites in central Canada where a rapid breakdown in resistance had been documented, SNPs in about half
of the genes differed between collections before and after the change. This indicated that the ‘new’
pathotypes were likely not the result of point mutation, but rather presented genotypes that had been
maintained in the pathogen population at low frequency through balancing selection. These ‘new’
pathotypes became dominant at each site in response to selection from repeated exposure to resistant
hosts.

Afsaneh Sedaghatkish (asedagha@uoguelph.ca)

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