Genetic and molecular analysis of clubroot resistance in canola introgressed from rutabaga cvs. Polycross and Brookfield

  • Author / Creator
    Wang, Zhengping
  • Clubroot disease caused by Plasmodiophora brassicae is a serious threat to canola (Brassica napus) production. The evolution of new pathotypes has rendered available resistances ineffective and has necessitated the introgression of new resistance into canola and furthering our understanding of the genetic and molecular basis of the resistance. Clubroot resistance from rutabaga (B. napus var. napobrassica) cvs. Polycross and Brookfield has been introgressed into canola in a previous study. In the first study outlined in this thesis, I report the genetic and molecular basis of clubroot resistance in canola, introgressed from a rutabaga cv. Polycross, by using a doubled haploid (DH) mapping population. Whole genome resequencing-based bulked segregant analysis followed by genetic mapping was carried out to identify the genomic regions contributing to this resistance, and expression analysis of the genes from the quantitative trait loci (QTL) regions was carried out to understand the molecular basis of this resistance. Following this approach, two major QTL located at 14.41-15.44 Mb of A03 and at 9.96-11.09 Mb of A08 chromosomes and their interaction was observed to confer resistance to pathotypes 3H, 3A and 3D. Analysis of the genes from the two QTL regions suggested that decreased expression of sugar transporter genes may play an important role in resistance conferred by the A03 QTL, while increased expression of the TNL genes could be the major determinant of the resistance conferred by the A08 QTL. SNP allele-specific PCR-based markers, which could be detected by agarose gel electrophoresis, were also developed from the two QTL regions for use in breeding including pyramiding of multiple clubroot resistance genes. In the second study described in this thesis, I investigated four putative clubroot resistance genes and long noncoding RNAs (lncRNAs) from primary and secondary metabolic pathways through overexpression in Arabidopsis thaliana; these genes and lncRNAs were identified through transcriptome analysis of B. napus lines carrying clubroot resistance of the rutabaga cv. Brookfield. However, none of the homozygous transgenic A. thaliana lines carrying the above-mentioned genes or lncRNAs showed resistance to clubroot disease suggesting that these genes and lncRNAs may not be directly involved in clubroot resistance. Thus, the knowledge and materials generated from this thesis research can be used in breeding canola for durable resistance clubroot disease.

  • Subjects / Keywords
  • Graduation date
    Fall 2022
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.