Theor Appl Genet (2010) 120:1621–1634 DOI 10.1007/s00122-010-1281-1 123 ORIGINAL PAPER Genetic and physical Wne mapping of Scmv2, a potyvirus resistance gene in maize Christina Roenn Ingvardsen · Yongzhong Xing · Ursula Karoline Frei · Thomas Lübberstedt Received: 8 June 2009 / Accepted: 24 January 2010 / Published online: 14 February 2010  Springer-Verlag 2010 Abstract Sugarcane mosaic virus (SCMV) is an important virus pathogen both in European and Chinese maize produc- tion, causing serious losses in grain and forage yield in sus- ceptible cultivars. Two major resistance loci confer resistance to SCMV, one located on chromosome 3 (Scmv2) and one on chromosome 6 (Scmv1). We developed a large isogenic map- ping population segregating in the Scmv2, but not the Scmv1 region, to minimize genetic variation potentially aVecting expression of SCMV resistance. We Wne mapped Scmv2 to a region of 0.28 cM, covering a physical distance of 1.3426 Mb, and developed six new polymorphic SSR markers based on publicly available BAC sequences within this region. At pres- ent, we still have three recombinants left between Scmv2 and the nearest polymorphic marker on either side of the Scmv2 locus. The region showed synteny to a 1.6 Mb long sequence on chromosome 12 in rice. Analysis of the public B73 BAC library as well as the syntenic rice region did not reveal any similarity to known resistance genes. However, four new can- didate genes with a possible involvement in movement of virus were detected. Introduction Sugarcane mosaic virus (SCMV) is an important virus pathogen both in European and Chinese maize production, causing serious losses in grain and forage yield in susceptible cultivars (Fuchs and Grüntzig 1995). SCMV belongs together with maize dwarf mosaic virus (MDMV), Johnsongrass mosaic virus (JGMV), sorghum mosaic virus (SrMV), and Zea mosaic virus (ZeMV) to the sugarcane mosaic sub- group of the Potyviridae, all being maize pathogens (Kuntze et al. 1995; Seifers et al. 2000). The diagnostic symptoms of SCMV include stunting, chlorosis, reduction in plant biomass, and, therefore, a reduction in grain and forage yield. Chemical control of SCMV and its vectors is not possible due to the non-persistent mode of virus transmission by aphids. Hence, the most eYcient method to control SCMV infections is the cultivation of resistant maize varieties. Kuntze et al. (1997) screened 122 early maturing European maize inbreds under both greenhouse and Weld Communicated by C. Schön. C. R. Ingvardsen and Y. Xing contributed equally to this work. C. R. Ingvardsen · Y. Xing · U. K. Frei · T. Lübberstedt Department of Genetics and Biotechnology, Faculty of Agricultural Sciences, University of Aarhus, Forsøgsvej 1, 4200 Slagelse, Denmark Present Address: C. R. Ingvardsen (&) Department of Agriculture and Ecology, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark e-mail: cri@life.ku.dk Present Address: Y. Xing National Key Lab of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China e-mail: yzxing@mail.hzau.edu.cn Present Address: U. K. Frei Iowa State University Plant Sciences Institute, 1218 Agronomy, Ames, IA 50011, USA e-mail: ufrei@iastate.edu Present Address: T. Lübberstedt Department of Agronomy, Iowa State University, 1204 Agronomy Hall, Ames, IA 50011, USA e-mail: thomasL@iastate.edu