Effect of Sclerotinia sclerotiorum on the plant defense response in Brassica napus and Arabidopsis thaliana
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Date
2014-08-22
Authors
Mao, Xingyu
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Abstract
The fungal pathogen S. sclerotiorum (Sclerotinia sclerotiorum) impacts production and yield in one of Canada’s number one crops, canola (Brassica napus). Unfortunately, few cultivars show any tolerance to this devastating fungal pathogen. Thus, understanding how the plant responds to this aggressive fungus at the cellular level will facilitate the identification of genes and gene products responsible for improved plant performance. While our understanding of the host pathogen interaction is becoming clearer, there is remarkably little information available for Sclerotinia, especially its pathogenicity in canola. Moreover, we know nothing about how this interaction is specified at the cellular, physiological or molecular level directly at the site of infection in mature leaves following petal inoculation. Thus, we compared differences in plant structure, antioxidant response, and genes involved in the salicylic acid, jasmonic acid and ethylene defense pathways in a susceptible cultivar, Westar, and a previously described tolerant cultivar, Zhongyou821 (ZY821). Our data showed that at the cellular level, ZY821 was able to suppress the Sclerotinia penetration. The ascorbate-glutathione pathway and resistant signaling pathways were all associated with the canola defense response to S. sclerotiorum, while stronger antioxidant and signaling pathways responses were observed in ZY821 leaves at the site of infection. Also, transcriptional regulators not previously associated with plant defense in the Arabidopsis- S. sclerotiorum pathosystem were identified through bioinformatics approaches. By comparing plant susceptibility to S. sclerotiorum between Arabidopsis wild type and seven loss-of-function mutants, I found transcription factor JAM2 might be involved in plant tolerance to S. sclerotiorum.
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Keywords
canola, Sclerotinia, plant defense response, antioxidant, microscopy, bioinformatics, Arabidopsis