title: Fine mapping of Rcr1 and analyses of its effect on transcriptome patterns during infection by Plasmodiophora brassicae.
abstract: BACKGROUND
  The protist Plasmodiophora brassicae is a biotrophic soil-borne pathogen that causes clubroot on Brassica crops worldwide. Clubroot disease is a serious threat to the 8 M ha of canola (Brassica napus) grown annually in western Canada. While host resistance is the key to clubroot management, sources of resistance are limited.
  
  
  RESULTS
  To identify new sources of clubroot resistance (CR), we fine mapped a CR gene (Rcr1) from B. rapa ssp. chinensis to the region between 24.26 Mb and 24.50 Mb on the linkage group A03, with several closely linked markers identified. Transcriptome analysis was conducted using RNA sequencing on a segregating F1 population inoculated with P. brassicae, with 2,212 differentially expressed genes (DEGs) identified between plants carrying and not carrying Rcr1. Functional annotation of these DEGs showed that several defense-related biological processes, including signaling and metabolism of jasmonate and ethylene, defensive deposition of callose and biosynthesis of indole-containing compounds, were up-regulated significantly in plants carrying Rcr1 while genes involved in salicylic acid metabolic and signaling pathways were generally not elevated. Several DEGs involved in metabolism potentially related to clubroot symptom development, including auxin biosynthesis and cell growth/development, showed significantly lower expression in plants carrying Rcr1.
  
  
  CONCLUSIONS
  The CR gene Rcr1 and closely linked markers will be highly useful for breeding new resistant canola cultivars. The identification of DEGs between inoculated plants carrying and not carrying Rcr1 is an important step towards understanding of specific metabolic/signaling pathways in clubroot resistance mediated by Rcr1. This information may help judicious use of CR genes with complementary resistance mechanisms for durable clubroot resistance.
authors.forename: Mingguang
authors.initials: M
authors.lastname: Chu
authors.forename: Tao
authors.initials: T
authors.lastname: Song
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Falk
authors.forename: Xingguo
authors.initials: X
authors.lastname: Zhang
authors.forename: Xunjia
authors.initials: X
authors.lastname: Liu
authors.forename: Adrian
authors.initials: A
authors.lastname: Chang
authors.forename: Rachid
authors.initials: R
authors.lastname: Lahlali
authors.forename: Linda
authors.initials: L
authors.lastname: McGregor
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Gossen
authors.affiliation: Department of Agriculture and Agri-Food Canada (AAFC), Saskatoon Research Centre, 107 Science Place, Saskatoon, Saskatchewan S7N 0X2, Canada. gary.peng@agr.gc.ca.
authors.forename: Gary
authors.initials: G
authors.lastname: Peng
authors.forename: Fengqun
authors.initials: F
authors.lastname: Yu
mesh_terms: D000483:Alleles; D001937:Brassica / Q000235:genetics* / Q000469:parasitology*; D002874:Chromosome Mapping; D019295:Computational Biology; D003433:Crosses, Genetic; D060467:Disease Resistance / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D005799:Genes, Dominant; D017343:Genes, Plant; D008040:Genetic Linkage; D005819:Genetic Markers; D005838:Genotype; D059014:High-Throughput Nucleotide Sequencing; D058977:Molecular Sequence Annotation; D010641:Phenotype; D010935:Plant Diseases / Q000469:parasitology*; D056909:Plasmodiophorida; D015203:Reproducibility of Results; D059467:Transcriptome
chemical_list: D005819:Genetic Markers