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RNAseq and histological analysis of the canola – Sclerotinia pathosystem
s. MAO (1), M. F. Belmonte (1), D. Fernando (1), T. De Kievit (1). (1) University of Manitoba, Winnipeg, MB, Canada

The fungal pathogen Sclerotinia (<i>Sclerotinia sclerotiorum</i>) impacts production and yield in one of Canada’s number one crops, canola (<i>Brassica napus</i>). Unfortunately, few cultivars show tolerance to this devastating fungal pathogen. Thus, understanding the plant’s response to this aggressive fungus is paramount in the identification of resistance genes. While our understanding of the host pathogen interaction is becoming clearer, there is remarkably little information available for Sclerotinia-canola pathosystem. Moreover, we know nothing about how this interaction is specified at the genetic or cellular level. Therefore, we have taken an initiative to compare all of the genes expressed both a susceptible cultivar (Westar) and a partially tolerant cultivar [Zhongyou821 (ZY821)] when challenged with Sclerotinia using global RNAseq strategies. We complement the global RNA profiling data with detailed anatomical studies and validations using qRT-PCR. At the cellular level, Sclerotinia penetrates both cultivar leaves directly through the cuticle and epidermis rather than through stomata openings. While Sclerotinia growth is prevalent on the epidermis of ZY821, pathogen entry into the subtending layers is slowed. Genes associated with defense response signaling pathways including AOS and <i>PR1</i> express differently at the later infection stages. Collectively, our data provides both anatomical and predicted molecular mechanisms underlying canola’s response to Sclerotinia.

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