Two distinct potato late blight resistance genes from Solanum berthaultii are located on chromosome 10

For breeding potato varieties resistant to late blight, identification of resistance genes to Phytophthora infestans (Rpi genes) is essential. Introduction of Rpi genes from wild Solanum species into cultivated potato is likely to be a good method to achieve durable resistance to P. infestans. In this study, we identified two Rpi genes (Rpi-ber1 and Rpi-ber2) derived from two different accessions of Solanum berthaultii. These two genes are closely linked on the long arm of chromosome 10. There are similarities between the predicted genetic locations of the previously identified Rpi-ber and Rpi-ber1, which given the common origin of these genes, may indicate that they are the same. However, the genetic positions of Rpi-ber1 and Rpi-ber2 are different. Rpi-ber1 is positioned between CT214 and TG63, whereas Rpi-ber2 is located below both of these two markers. In addition, the sequences of four linked markers to both R genes showed different polymorphisms indicating the two Rpi genes could be transmitted from different haplotypes (chromosomes).