Genetic Analysis of a Horizontal Resistance Locus in .

causes blackleg disease in . The blackleg disease is mainly controlled by resistance genes in . Previous studies have shown that the blackleg resistant locus that conferred horizontal resistance under field conditions, is located on chromosome A10 of . The purpose of this study is to fine map this locus and hence identify a candidate gene underlying horizontal resistance. The spectrum of resistance to isolates of the resistance locus was analyzed using near isogenic lines, resistant, and susceptible cultivars. The results showed that this locus was horizontally resistant to all isolates tested. Sequence characterized amplified regions (SCAR), simple sequence repeats (SSR), and single nucleotide polymorphism (SNP) markers were developed in the chromosome region of and a fine genetic map was constructed. Two molecular markers narrowed in a 53.37 kb region where six genes were annotated. Among the six annotated genes, encoding a cytochrome P450 protein were predicted as the candidate of . Based on the profiling of pathogen induced transcriptome, three expressed genes in the six annotated genes were identified while only cytochrome showed upregulation. The candidate corresponds to the gene involved in the indole glucosinolate biosynthesis pathway and plant basal defense in . The molecular markers identified in this study will allow the quick incorporation of the allele in rapeseed cultivars to enhance blackleg resistance.