Comparative transcriptome analysis of rutabaga (Brassica napus) cultivars in response to Plasmodiophora brassicae

• Author / Creator

  Zhou, Qinqin

• Clubroot, a soil-borne disease caused by the obligate parasite Plasmodiophora brassicae Woronin, is a threat to canola (Brassica napus L.) production in western Canada. Genetic resistance represents the most effective tool to manage this disease. To improve understanding of the mechanisms of resistance and pathogenesis in the clubroot pathosystem, the rutabaga (B. napus subsp. rapifera Metzg) cultivars ‘Wilhelmsburger’ (resistant) and ‘Laurentian’ (susceptible) were inoculated with P. brassicae pathotype 3A and their transcriptomes were analyzed at 7, 14 and 21 days after inoculation (dai) by RNA sequencing (RNA-seq). Thousands of transcripts with significant changes in expression were identified in each host at each time-point in inoculated vs. non-inoculated plants. Molecular responses at 7 and 14 dai supported clear differences in the clubroot resistance of the two genotypes. Both the resistant and the susceptible cultivars activated receptor-like protein (RLP) genes, resistance (R) genes and salicylic acid (SA) signaling as clubroot defense mechanisms. In addition, genes related to calcium signaling, and genes encoding leucine-rich repeat (LRR) receptor kinases, the respiratory burst oxidase homolog protein, and transcription factors such as WRKYs, ethylene responsive factors and bZIPs, appeared to be upregulated in ‘Wilhelmsburger’ to restrict P. brassicae development. Some of these genes are essential components of molecular defenses, including ethylene (ET) signaling and the oxidative burst. Our study highlights the importance of the activation of both SA- and ET-mediated responses in the resistant cultivar. A set of candidate genes showing contrasting patterns of expression between the resistant and susceptible cultivars was identified, representing potential targets for further study and validation through approaches such as gene editing.

• Subjects / Keywords

  • Brassica napus
  • Plasmodiophora brassicae
  • clubroot
  • defense mechanisms
  • salicylic acid
  • RNA-seq
  • ethylene

• Graduation date

  Fall 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-zk7a-a262

• License

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