Identification of SRAP markers linked to the restorer gene of CMS7311 in heading Chinese cabbage [Brassica rapa L. subsp. pekinensis (Lour.) Olsson]

In order to map the restorer gene BrRfp of the polima (pol)-like cytoplasmic male sterility (CMS) 06J45 line of heading Chinese cabbage, a segregating population consisting of 258 F₂ progeny of CMS06J45 and the restorer line 01S325 was tested by sequence-related amplified polymorphism (SRAP) combined with the bulked segregant analysis method. As a result, two SRAP markers, me3em3.366 and pm88bg5.263, linked with the BrRfp gene were identified from 463 SRAP primer pairs. By cloning, sequencing, and basic local alignment search tool analysis, the two markers were targeted to the BGIScaffold000053 of Brassica rapa in the Brassica database. Linkage analysis showed that these markers were distributed on either side of the BrRfp gene, the linkage distances of the two markers were 1.30 and 0.54 cM, respectively, and the BrRfp gene was restricted to the chromosome A09 genomic region of B. rapa. Moreover, the special me3em3.366 marker was a co-dominant marker and was successfully converted into a SCAR dominant marker. These specific markers provide basic information for map-based cloning of the BrRfp gene and will be very valuable for marker-assisted selection of a new restorer line of heading Chinese cabbage.