Development of SCAR markers to the PVY resistance gene Ry(adg) based on a common feature of plant disease resistance genes

Sequence-characterized amplified regions (SCARs) were developed, based on n ucleotide differences within resistance gene-like fragments isolated from a potato plant carrying the Ry(adg) gene, which confers extreme resistance t o potato Y potyvirus (PVY). It originates from Solanum tuberosum subsp. and igena, and a susceptible potato plant. SCARs were tested using 103 potato b reeding lines and cultivars with diverse genetic backgrounds derived from E urope, North America, and Japan. Two markers showed high accuracy for detec tion of the Ry(adg) gene. The SCAR marker RYSC3 was generated only in genot ypes carrying Ry(adg). The SCAR marker RYSC4 was detected in all genotypes carrying Ry(adg) but also in four PVY-susceptible genotypes. Neither marker was detected in genotypes carrying other Ry genes originating from differe nt species than S. tuberosum subsp. andigena. Therefore, these SCAR markers should be powerful tools in marker-assisted selection for Ry(adg) in potat o breeding programs, and should also be useful for cloning of the Ry(adg) g ene.