Development of gene-based markers for the Bs2 bacterial spot resistance gene for marker-assisted selection in pepper (Capsicum spp.)

The Bs2 gene of pepper (Capsicum spp.) confers resistance to the most commonly detected races of Xanthomonas campestris pv vesicatora (Xcv). Using information from a published database, we developed gene-based markers for selection of Bs2 in pepper. High polymorphism was detected in exon 3, intron 2 and 3’-UTR of the Bs2 gene. The three regions were sequenced and numerous SNPs and In/Dels were identified between resistant and susceptible inbred lines. Seven SNPs were selected to develop SNP markers using the tetra-primer amplification refractory mutation system-PCR methodology (Tetra-primer ARMS-PCR). One SNP (G/C) was used to develop a molecular marker that can perfectly identify the presence of the bacterial spot resistance. The gene-based markers were further validated to test association with resistance in 80 lines and cultivars. The markers successfully identified a bell pepper commercial cultivar 62-2 that harbors the Bs2 gene. The successful development of the markers in this study provides a useful tool for MAS to screen the Bs2 gene in pepper.