Inheritance Pattern and Molecular Markers for Resistance to Blackleg Disease in Cabbage.

The inheritance and causal loci for resistance to blackleg, a devastating disease of Brassicaceous crops, are yet to be known in cabbage ( L.). Here, we report the pattern of inheritance and linked molecular marker for this trait. A segregating BC population consisting of 253 plants was raised from resistant and susceptible parents, L29 (♀) and L16 (♂), respectively. Cotyledon resistance bioassay of BC population, measured based on a scale of 0-9 at 12 days after inoculation with isolate 03-02 s, revealed the segregation of resistance and ratio, indicative of dominant monogenic control of the trait. Investigation of potential polymorphism in the previously identified differentially expressed genes within the collinear region of ' blackleg resistant loci ' in identified two insertion/deletion (InDel) mutations in the intron and numerous single nucleotide polymorphisms (SNPs) throughout the LRR-RLK gene , of which six SNPs in the first exon caused the loss of two LRR domains in the susceptible line. An InDel marker, based on the InDel mutations, and a high resolution melting (HRM) marker, based on the SNP CT in the second exon were developed, which predicated the resistance status of the BC population with 80.24%, and of 24 commercial inbred lines with 100% detection accuracy. This is the first report of inheritance and molecular markers linked with blackleg resistance in cabbage. This study will enhance our understanding of the trait, and will be helpful in marker assisted breeding aiming at developing resistant cabbage varieties.