Development of PCR-based markers for discriminating Solanum berthaultii using its complete chloroplast genome sequence

Solanum berthaultii is one of the wild diploid Solanum species, which is an excellent resource in potato breeding owing to its resistance to several important pathogens. On the other hand, sexual hybridization between S. berthaultii and S. tuberosum (potato) is limited because of their sexual incompatibility. Therefore, cell fusion can be used to introgress various novel traits from this wild species into the cultivated potatoes. After cell fusion, it is crucial to identify fusion products with the aid of molecular markers. In this study, the chloroplast genome sequence of S. berthaultii obtained by next-generation sequencing technology was described and compared with those of five other Solanum species to develop S. berthaultii specific markers. A total sequence length of the chloroplast genome is 155,533 bp. The structural organization of the chloroplast genome is similar to those of the five other Solanum species. Phylogenic analysis with 25 other Solanaceae species revealed that S. berthaultii is most closely located with S. tuberosum. Additional comparison of the chloroplast genome sequence with those of the five Solanum species revealed 25 SNPs specific to S. berthaultii. Based on these SNPs, six PCR-based markers for differentiating S. berthaultii from other Solanum species were developed. These markers will facilitate the selection of fusion products and accelerate potato breeding using S. berthaultii.