Piotr Kopeć1, Katarzyna  Mikolajczyk2, Ewa Jajor3, Agnieszka  Perek3, Joanna  Nowakowska2, Christian  Obermeier4, Harmeet Singh  Chawla4,5, Marek  Korbas3, Iwona  Bartkowiak-Broda2, Wojciech M.  Karlowski1 

1Department of Computational Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University Poznan, Poznan, Poland,
2Department of Genetics and Breeding of Oilseed Crops, Plant Breeding and Acclimatization Institute-National Research Institute, Poznan, Poland,
3Institute of Plant Protection – National Research Institute, Poznan, Poland,
4Department of Plant Breeding, Justus-Liebig-Universitaet Giessen,, Giessen, Germany,
5Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany

The aim of our study was to define and characterize the clubroot resistance locus in the winter oilseed rape cultivar “Tosca”. Following a cross between “Tosca” and a clubroot susceptible line, we have developed a segregating DH population, which was genotyped with Brassica 60k SNP chip, and phenotyped for morphological symptoms, after being challenged with Plasmodiophora brassicae resting spores. We have performed an association analysis, which led to the identification of the ~100 kbp long major-effect resistance locus on the A03 chromosome. Analysis of the genetic and physical evidence showed that the locus corresponds to the Crr3 locus known from the earlier studies on Brassica rapa. Using Oxford Nanopore sequencing we have described the local differences between resistant and susceptible parents. The most striking difference was a tandem duplication of the entire NBS gene. The homologous genes were highly polymorphic between the parents, especially in the pattern-recognizing LRR domain. Leveraging the polymorphisms we have designed homolog-specific markers, which we have tested on a panel of clubroot-resistant Brassica cultivars.


Dr. Katarzyna Mikolajczyk is currently a Head of the Research Division and the Department of Oil Crops of the Plant Breeding and Acclimatization Institute – NRI in Poznan, Poland. She works on the development of DNA markers suitable for marker-assisted breeding of oilseed rape (Brassica napus L.). She was a co-creator and coordinator of the research project which ended last year and resulted in mapping the clubroot resistance locus of the Swedish resynthesis-derived winter-type oilseed rape cultivar “Tosca”. Recently, Dr. Mikolajczyk has co-invented a new qPCR assay for determining the homo- and heterozygous genotypes of B. napus with the ogu-INRA Rfo restorer gene. She is also keen on swing&bluesand bike rides.



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