Inheritance of Black Rot Resistance and Development of Molecular Marker Linked to Races 6 and 7 Resistance in Cabbage.

Black rot, caused by pv. (), produces V-shaped chlorotic lesions on the leaves of cabbage ( var. L.), causing darkened veins and drastically reducing yield and quality. Of the 11 races identified, races 1, 4, and 6 are predominant globally. In the present study, we aimed to develop a molecular marker linked to black rot resistance against races 6 and 7. Crossed between black rot-resistant ('SCNU-C-3470') and -susceptible ('SCNU-C-3328') lines obtained 186 F plants. Resistance to race 6 segregated in a 3:1 (susceptible:resistant) ratio in the F population, which is consistent with a monogenic recessive trait. Nucleotide-binding site (NBS) leucine rich repeat (LRR)-encoding resistance () genes play a crucial role in plant defenses to various pathogens. The candidate gene () located on chromosome C08, previously reported by our research group, was cloned and sequenced in resistant and susceptible cabbage lines. The gene consisted of a single exon with a 3 bp insertion/deletions (InDels), a 292 bp polymorphism (an insertion in the exon of the resistant line relative to the susceptible line) and several single nucleotide polymorphisms (SNPs). Here, we developed the InDel marker BR6-InDel to assess linkage between variation at and resistance to races 6 and 7. This marker will help cabbage breeders develop cabbage cultivars resistant to races 6 and 7.