Abstract: With a F2 population between a highly resistant parent and a highly susceptible parent(Q9×Q10)as materials，polymorphism between resistant and susceptible bulk of cucunlber powdery mildew were studied using BSA method and AFIJP technology． A Co-dominant AFLP marker，P18M47—238 bp／236 bp，was screened．The resistant and susceptible F!plants possessed the 238 bp and the 236 bp fragment，respectively， and the mid-plants owned the two fragments．Linkage analysis indicated that the AFLP marker was tightly linked to the cucunlber powdery mildew resistance related gene， and the genetic distance was 5.56cM． Sequencing of the fragments of the Co-dominant AFLP marker indicated that their lengths were 238 bp and 236 bp respectively．The difference of the two fragments lied in the insert-deletion (indel)of two“T”base．BLAST analysis revealed that the two fragments were new in the GeneBank．

Key words: Cucumber, Powdery mildew, Resistance-related gene, Molecular marker, AFLP