ORIGINAL PAPER SSR and SCAR mapping of a multiple-allele male-sterile gene in Chinese cabbage (Brassica rapa L.) Hui Feng Æ Peng Wei Æ Zhong-Yun Piao Æ Zhi-Yong Liu Æ Cheng-Yu Li Æ Yu-Gang Wang Æ Rui-Qin Ji Æ Shu-Juan Ji Æ Ting Zou Æ Su-Ryun Choi Æ Yong-Pyo Lim Received: 17 December 2008 / Accepted: 9 April 2009 / Published online: 13 May 2009 Ó Springer-Verlag 2009 Abstract The genic multiple-allele inherited male-sterile gene Ms in Chinese cabbage (Brassica rapa L.) was identified as a spontaneous mutation. Applying this gene to hybrid seed production, several B. rapa cultivars have been successfully bred in China. A BC 1 population (244 plants) was constructed for mapping the Ms gene. Screening 268 simple sequence repeat (SSR) markers which cover the entire genome of Chinese cabbage was performed with bulked segregant analysis (BSA). On the basis of linkage analysis, the Ms gene was located on linkage group R07. In addition, through the amplified fragment length polymor- phism (AFLP) and the sequence-characterized amplified region (SCAR) techniques combining BSA, two SCAR markers which were converted from corresponding AFLP markers flanked the Ms gene. Finally, a genetic map of the Ms gene was constructed covering a total interval of 9.0 cM. Two SCAR markers, syau_scr01 and syau_scr04, flanked the Ms gene at distances of 0.8 and 2.5 cM, respectively. All the SSR markers (cnu_m273, cnu_m030, cnu_m295, and syau_m13) were mapped on the same side of the gene as syau_scr04, the nearest one of which, syau_m13, was mapped at a distance of 3.3 cM. These SSR and SCAR markers may be useful in marker-assisted selection and map-based cloning. Introduction Chinese cabbage (Brassica rapa L.) is a typically alloga- mous plant with bisexual flowers and obvious heterosis. The utilization of male-sterile lines is an economical and stable way to improve the cross-breeding of Chinese cab- bage. The percentage of male-sterile plants in an ideal male-sterile line should be 100%, and the combining ability of its major economic traits should also be high. In order to obtain such a high quality male-sterile line, it is crucial to search the male sterility source and reveal the underlying genetic mechanism. The male-sterile materials of Chinese cabbage can be divided into genic male sterility (GMS) and cytoplasmic male sterility (CMS) (van der Meer 1987). GMS has more obvious advantages, such as stable and complete sterility performance, extensive distribution of restorers, and no negative cytoplasmic effects. However, the known GMS in Chinese cabbage is considered to be mainly controlled by monogenic recessive or dominant genes. If testcrosses are employed in the selection of maintaining lines of the male sterility, a maximum of 50% of the plants in these lines will be sterile. In the utilization of such male-sterile resources, a pronounced drawback is the required manual removal of the fertile plants from the female parent line (van der Meer 1987). Feng et al. (1995, 1996) obtained four stable hereditary lines comprising 100% male-sterile plants in Chinese cabbage and proposed a genetic hypothesis of a genic Communicated by C. Quiros. Electronic supplementary material The online version of this article (doi:10.1007/s00122-009-1042-1) contains supplementary material, which is available to authorized users. H. Feng (&)  P. Wei  Z.-Y. Piao  Z.-Y. Liu  C.-Y. Li  Y.-G. Wang  R.-Q. Ji  S.-J. Ji  T. Zou Department of Horticulture, Shenyang Agricultural University, Shenyang, China e-mail: fenghuiaaa@263.net S.-R. Choi  Y.-P. Lim Department of Horticulture, Chungnam National University, Daejeon, Korea 123 Theor Appl Genet (2009) 119:333–339 DOI 10.1007/s00122-009-1042-1