Tsw, a single dominant resistant gene against Tomato spotted wilt virus (TSWV), has been mapped on chromosome 10 in Capsicum. Previously found molecular markers linked to the Tsw gene are not transferable for all pepper breeding materials. To develop segregating populations for the Tsw, commercial F1 cultivar C. annuum ‘Telmo’ was self-pollinated. An F2 population was obtained from the self-pollination of F1 plants deriving from a cross between C. annuum ‘Special’ and C. chinense ‘PI152225’. Twelve additional molecular markers linked to the Tsw gene were developed using tomato and pepper genome sequence database. A tomato scaffold sequence of 7841 kb in size covering the corresponding region of the Tsw locus was identified based on the sequence of Tsw-linked marker. Analyzing the tomato scaffold sequence, two sequences of pepper scaffold and contig at down and up site of the Tsw locus, respectively, were located. Three SNP markers linked to the Tsw locus (HRM1, HRM2, and HRM3) were developed using the pepper scaffold sequence of 419 kb in size. All three markers showed 2 recombinants (1.0 cM) out of 198 individuals of F2 ‘Telmo’ population. When analyzing these SNP markers in an F2 population deriving from C. annuum ‘Special’ and C. chinense ‘PI152225’, we detected 5 recombinants (0.76 cM) out of 659 individuals. HRM4, a SNP marker linked to the Tsw gene, was developed with a 99 kb pepper contig sequence. It showed 7 recombinants (3.5 cM) out of 198 individuals of F2 ‘Telmo’ population. We found 5 recombinants (0.76 cM) out of 659 individuals when HRM4 was analyzed in F2 population derived from C. annuum ‘Special’ and C. chinense ‘PI152225’. To narrow down the molecular markers linked to the Tsw locus, four SNP markers, HRM5, HRM6, HRM7, and HRM8, were developed with the pepper scaffold sequence. All of them showed 5 recombinants (0.76 cM) out of 659 individuals of F2 ‘SP’ population. Four other SNP markers, HRM9, HRM10, HRM11, and HRM12, were developed using the pepper contig sequence. HRM9 showed 5 recombinants (0.76 cM), HRM10 showed 4 recombinants (0.61 cM), and HRM11 and HRM12 showed 3 recombinants (0.46 cM) out of 659 individuals of F2 ‘SP’ population. The SNP markers developed in this study will be useful for fine mapping of the Tsw gene and for developing cultivars which carry TSWV-resistance gene.

• Bong Nam Chung(Horticultural Environment Division, National Institute of Horticultural and Herbal Science)
• Hee-Bum Yang(Dept. of Plant Science and Vegetable Breeding Research Center of Agriculture and Life Sciences, Seoul National University)
• Ngoc Huy Hoang(Dept. of Plant Science and Vegetable Breeding Research Center of Agriculture and Life Sciences, Seoul National University)
• Byoung-Cheorl Kang(Dept. of Plant Science and Vegetable Breeding Research Center of Agriculture and Life Sciences, Seoul National University) Corresponding Author