Characterization of rutabaga for genetic diversity and as a source of clubroot resistance.

• Author / Creator

  Yu, Zhiyu

• Rutabaga (Brassica napus ssp. napobrassica (L.) Hanelt) is widely grown as a vegetable crop and animal fodder, and is reported to be an excellent source of clubroot (Plasmodiophora brassicae) resistance genes. In this study, the genetic diversity and clubroot resistance of 124 rutabaga accessions from the Nordic countries (Norway, Sweden, Finland, Denmark, and Iceland) were assessed using a 15K Brassica single nucleotide polymorphism (SNP) array. Filtering was done to remove markers that did not amplify genomic DNA, and monomorphic and low coverage site markers. Allelic frequency statistics calculated with the retained 6861 SNP markers indicated that the rutabaga accessions from Norway, Sweden, Finland and Denmark were not genetically different from each other. In contrast, accessions from these countries were significantly different from the Icelandic accessions (P < 0.05). The rutabaga accessions were also evaluated in the greenhouse for their reaction to five single-spore isolates representing P. brassicae pathotypes 2F, 3H, 5I, 6M, and 8N and 12 field isolates representing pathotypes 2B, 3A, 3O, 5C, 5G, 5K, 5L, 5X (two isolates, L-G2 and L-G3), 8E, 8J and 8P. The rutabaga accessions exhibited differential reactions to the 17 isolates with 0.8-46.4% resistant (R), 4.0-20.0% moderately resistant (MR) and 32.8-93.6% susceptible (S). Nine accessions with broad-spectrum (R + MR) resistance also were identified. The rutabaga accessions were genotyped with 63 PCR-based primers linked to previously identified clubroot resistance genes. Genome-wide association studies (GWAS) using the genotypic (SNP + PCR-based markers) and phenotypic data identified 45 SNPs (36 on the A-genome and 9 on the C-genome or scaffolds) and 4 PCR-based markers that were associated strongly with resistance to isolates representing 13 pathotypes (2F, 3H, 5I, 6M, 8N, 2B, 3A, 3O, 5C, 5G, 5K, 5L and 8P). The SNPs identified in this study will be important for marker-assisted breeding (MAS) of clubroot resistant cruciferous crops. 

• Subjects / Keywords

  • Rutabaga
  • GWAS
  • Clubroot
  • Genetic Diversity

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-19hh-bx67

• License

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