Development of SCAR markers linked to the Ns locus in potato

A random amplified polymorphic DNA marker OPG17(450) linked to the Ns gene that confers resistance of potato to potato virus S (PVS), was used to deve lop sequence-characterized amplified region (SCAR) markers. After cloning a nd sequencing of OPG17(450) new polymerase chain reaction (PCR) primers wer e designed to generate dominant (SCG17(321)) and codominant (SCG17(448)) ma rkers. For SCG17(448), polymorphism between susceptible and resistant genot ypes was recovered after digestion of the marker with the restriction enzym e MunI. In addition to the band corresponding to 'susceptible' allele that does not contain the MunI cleavage site, two bands of approximately 251 bp and 197 bp were observed in the resistant genotypes. The usefulness of thes e SCAR markers was verified in diploid potatoes possessing the Ns locus fro m clone G-LKS 678147/60, and in tetraploid potatoes derived from G-LKS 6781 47/60 and from clone MPI 65118/3.