Page 154 - PC2019 Program & Proceedings

PLANT CANADA 2019

S93. Transcriptome profiling of incompatible and compatible interactions between Brassica napus
and Leptosphaeria maculans
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*1
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Padmathilake, R. ; H. Sonah ; S. Jia ; Z. Zou ; J. Tucker ; A. Carter ; M-E. Balesdent ; P. Hu ; R.
Bélanger ; D. Fernando 1
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1 University of Manitoba; Université Laval
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3 Agriculture & Agri-Food Canada; UMR INRA AgroParisTech BIOGER
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Canola (Brassica napus) is a 26-billion-dollar crop in Canada. Leptosphaeria maculans causes blackleg
disease, the most economically significant disease of canola. B. napus genotype, ‘01-23-2-1’ that contains
only Rlm7 was inoculated with a L. maculans isolate (UMAvr7) carrying AvrLm7, and with the CRISPR
knockout AvrLm7 mutant (umavr7) of the same isolate carrying avrLm7 to represent incompatible and
compatible interactions, respectively. A dual RNA-seq experiment was done to explore differential gene
expressions during both interactions. Defense-related Gene Ontology analysis revealed calcium and iron
ion binding, chitinase, glutathione peroxidase, oxidoreductase, hydrolase, and methyltransferase activities
related genes expression started early at one dpi and significantly increased from seven dpi onwards in
incompatible Rlm7-AvrLm7 interaction. In contrast, compatible interaction showed no or very low-level
expression of those genes at 1-dpi and 3-dpi but significantly very high expression levels at 7-dpi
onwards compared to incompatible interaction. Westar with no R proteins showed compatible interactions
with both isolates and the expression patterns of aforesaid genes were similar to the compatible
interaction of Rlm7 with umavr7 giving disease. In the incompatible avirulence effector -R receptor
interaction, early activation of defense genes protects the host from the invading blackleg pathogen. This
is not the case when the host comprises no R protein or the pathogen possesses no avirulence protein
clearly highlighting the importance of gene-for-gene interactions in plant defense.

Rasanie Padmathilake (padmatkr@myumanitoba.ca)

S94. Tissue specific RNA sequencing of Brassica napus in response to Sclerotinia sclerotiorum
infection
Walker, P. *
University of Manitoba

White mold in Brassica napus (canola) is caused by the fungal pathogen Sclerotinia sclerotiorum and is
responsible for significant losses in crop yield across the globe. With advances in high-throughput
transcriptomics and computational biology, our understanding of canola’s defense response to S.
sclerotiorum is becoming clearer; however, the response of individual tissue layers directly at the site of
infection has yet to be explored. Using cutting edge laser-capture microdissection coupled with high-
throughput RNA sequencing we have profiled epidermal, mesophyll and vascular leaf tissues in response
to S. sclerotiorum infection. This strategy increases the number of genes detected compared to whole leaf
assessment and provides information on tissue-specific gene expression directly at the site of infection.
Our findings indicate distinct roles for each tissue layer in response to infection and our bioinformatics
approach has identified multiple novel defense regulators predicted to guide plant immunity. These
putative defense regulators were further characterized by challenging target knockout A. thaliana lines
with multiple fungal and bacterial pathogens. Using in planta infection assays we have identified both
broad spectrum and pathogen-specific target defense genes that are essential in reducing losses to
pathogen attack. We further discuss how this information will play a role in protecting one of Canada’s
most important cash crops against pathogenic attack.

Philip Walker (walkerp@myumanitoba.ca)

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