Page 295 - PC2019 Program & Proceedings

PLANT CANADA 2019

P163. A mycovirus cause hypovirulence in rice pathogen Microdochium albescens
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Murcia, J. ; R. Cascardo ; F. Souza ; M. Souza ; C. Farias ; D. Barros ; P. Alfenas
1 Universidade Federal de Pelotas
2 Universidade Federal de Viçosa
Mycoviruses are widely distributed in the major taxonomic groups of filamentous fungi. The association
established between mycovirus and their hosts may occur in a latent form or can change the phenotype of
the host causing hypervirulence or hypovirulence. In this study we describe a mycovirus infecting
Microdochium albescens, etiological agent of leaf scald in rice, and evaluated phenotype effects of virus
infection on the host. The mycovirus genome consists of four dsRNA segments with sizes of ≈2.5, 3.4,
3.5 and 3.8 kb. Viral particles with ≈40 nm were purified and the genomic segments were partially
sequenced. Together these results suggest that the virus isolated is a member of Chrysoviridae family. We
obtained a virus-free isogenic lineage and we found that the virus infected isolate produces 70% fewer
spores than virus free and presented 30% decrease in ground index. The isolated virus infected was less
aggressive than virus free isolate, with average in lesion length of 4.52 mm and 47.9 mm respectively.
Our results show that this mycovirus infection has a strong effect on M. albescens fitness and phenotype,
suggesting that the mycovirus isolated modulates important characteristics of the host that contributes to
pathogenicity. Together, the findings potentiate the use of this mycovirus as tools for studies on the
mechanisms of fungal pathogenicity as well as the use of these virus as biocontrol agents.

Johan Murcia (jmmurciab@unal.edu.co)

P164. Development of a novel, eco-friendly plant defense activator against Botrytis blight
Seifi, S.; A. Zarei; T. Hsiang; B. Shelp
University of Guelph

Conventional fungicides against gray mold disease are available, but they often do not offer complete
control, and negative health and environmental consequences have been ascribed to many of them.
Therefore, the development of novel resistance-enhancing and eco-friendly controls for such an important
disease is important for the production of field and horticultural crops, as well as for organic production in
particular. In this study, we report that exogenous application of the polyamine spermine (Spm) is
specifically effective in the induction of resistance against infection by the causal fungal agent, Botrytis
cinerea,on Arabidopsis, tomato and bean plants. RNA-Seq-based transcriptomic and microscopic
analyses revealed a priming role for Spm, leading to systemic-acquired resistance. Moreover, co-
application of Spm and salicylic acid (SA) resulted in a synergistic effect against the pathogen, leading to
higher levels of resistance than those induced by their separate applications. The Spm plus SA treatment
also reduced infection in systemic, non-treated leaves of tomato plants. Our findings suggest that the
Spm/SA mixture is a potent plant defense activator that leads to effective local and systemic resistance
against B. cinerea and possibly other necrotrophic pathogens.

Soren Seifi (hseifi@uoguelph.ca)

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