Page 180 - PC2019 Program & Proceedings

PLANT CANADA 2019

S145. Genomic and virulence differences between two sibling Clarireedia species causing dollar
spot on grasses
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Valliani, M. ; M. Nasr-Sharif; J. Wang; P. Goodwin; T. Hsiang
University of Guelph

The most common disease of intensively managed turfgrass in the lower Great Lakes region is dollar spot
caused by Clarireedia jacksonii on cool season grasses such as Agrostis stolonifera (creeping bentgrass).
Recently, the causal agent of this disease on warm season grasses was split from the cool season grass
pathogen and called C. monteithiana. The purpose of this research was to characterize these two sibling
species in terms of virulence differences on different grasses and genomic differences. In this study, both
species were found to be capable of attacking both cool season and warm season grasses, with C.
jacksonii seemingly causing more disease on all hosts. Isolates that had originated from warm season
grasses (all C. monteithiana) were ranked low-moderate for virulence on cool season grasses and the
warm season Cynodon dactylon. Among more than 10,000 genes for each fungal species (15 C. jacksonii,
11 C. monteithiana), the average similarity within species was 95% for C. jacksonii and 91% for C.
monteithiana, and between them it was 85%. This comparative genomic analysis supports the separation
of these two taxa into separate species. As well, the only known case of C. monteithiana in Canada was
on Trichophorum cespitosum, tufted bulrush, in Nova Scotia.

Moez Valliani (mvallian@uoguelph.ca)

S146. The first report of a culturable microbiome from pollinated style tissue
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1
1
*1
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Thompson, M. ; A. Shrestha ; J. Rinne ; C. Shearer ; V. Limay-Rios ; L. Reid ; M. Raizada
1
2
2
1 University of Guelph; Agriculture and Agrifood Canada
The style tissue of plants has not previously been explored for a microbiome including endophytes. In
plants, the style is the female reproductive tissue that transmits sperm nuclei from pollen to enable
fertilization, but it is also susceptible to pathogen entry. In maize, the styles are the unusually long silks,
which can be invaded by mycotoxin-producing pathogens such as Fusarium graminearum and
Aspergillus flavus (causative agents of Gibberella ear rot and Aspergillus ear rot, respectiely). We
hypothesized that maize genotypes that are partially resistant silk-invading pathogens house microbes in
the silk to defend the entryway to the developing grain. Fourteen genotypes of maize were grown in 2017,
open-pollinated, treated with and without F. graminearum, and the cobs were harvested at maturity. The
exposed tips of the silks were discarded, and the portion of the silks protected by the husk were split into
tip and base samples. Over 1000 microbes were isolated from these silks. Taxonomic identification of
these strains revealed that silks do indeed host a diversity of culturable bacteria and fungi. The
preliminary anti-Fusarium assays have discovered 3 candidate bacteria which suppress F. graminearum
growth in vitro. These microbes may have coevolved with maize to protect the grain from mycotoxigenic
fungi. They could potentially be used as a treatment to prevent toxins such as vomitoxin
(Deoxynivalenol), zearalenone, or aflatoxins from contaminating food.

Michelle Thompson (mthomp15@uoguelph.ca)

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