Survey and Application of DNA Makers Linked to TSWV Resistance

The incidence of Tomato spotted wilt virus (TSWV) in pepper was recently reported and TSWV has been rapidly spreading in Korea. However, TSWV-resistant pepper cultivars have not been developed in Korea so far. To develop resistant cultivars, establishment of a reliable resistance screening method is most critical. Mechanical inoculation of TSWV is known to be very inefficient due to many escapes. Hence, deployment of molecular markers linked to the TSWV resistance gene (Tsw) will greatly improve efficiency of TSWV- resistant cultivar breeding. In order to deploy TSWV resistance-linked markers in a paprika breeding program, we applied previously developed molecular markers, which include five random amplified polymorphic DNA (RAPD) and one cleaved amplified polymorphic sequence (CAPS) markers, on six resistant and 11 susceptible paprika cultivars along with original TSWV-resistant materials, Capsicum chinense PI152225 and PI159236. In addition, several other markers close to the resistance locus (Tsw) were selected by a map comparison and applied on the same materials. Except for the CAPS marker SCAC568, no markers showed consistent polymorphisms between resistant and susceptible pepper materials. SCAC568 produced polymorphisms between three resistant cultivars of Zeraim and all susceptible cultivars. When the SCAC568 marker was applied on a BCF₁ population of 92 individuals, genotypes of SCAC568 were cosegregated with phenotypes in 90 individuals out of 92. These results demonstrate that SCAC568 can be deployed in pepper breeding programs in combination with TSWV-resistant cultivars from Zeraim.