The invention belongs to the field of 
crop genetic breeding, and discloses a 
molecular marker for 
raphanus sativus L. 
downy mildew resistant 
gene close linkage. A sequence-related amplified polymorphism (SRAP) 
molecular marker method is used for carrying out marker 
genotyping on high-resistance 
downy mildew raphanus sativus L. parents (NAU-dhp08), high-sensitive 
downy mildew raphanus sativus L. parents (half green from autumn fields) and a second filial generation (F2) group 
single plant which is prepared through resistance and sensitive parent hybridization, through the F2 
single plant resistance 
phenotype and 
marker gene linkage analysis, a resistance marker Em9 / ga24370 of 370-
base pair (bp) close linkage is identified, a distance from a resistance locus and a marker 
genetic distance is 2.3 centimeters. The 
molecular marker method provided by the invention can be used for the 
marker assisted selection of raphanus sativus L. downy 
mildew resistance breeding, quickly and accurately identifies the raphanus sativus L. downy 
mildew resistance, overcomes the limitations of heavy 
workload, long period, easily influenced results by environment and the like of the conventional resistance identification method, the high-resistance 
gene selection efficiency can be obviously improved, so that a breeding process of a new high raphanus sativus L. downy 
mildew-resistant variety can be accelerated.