Resistance gene-like fragment ADG2 has been shown to co -segregate with Ryadg, which controls extreme resistance to potato Y potyvirus (PVY) in Solanum tuberosum subsp. andigena (Hamalainen et al. 1997(Hamalainen et al. , 1998. Applicability tests of ADG2 as a selection tool for resistance to PVY were carried out by genomic Southern analysis on a broad range of cultivars and breeding lines of potato and some other solanaceous species. A new marker band (10.5 kb associating with Ry was found in addition to previously reported 3.5 kb marker band. While the 3.5 kb marker was specifically linked to Ryadg with extremely high association (96 %), the newly identified 10.5 kb marker band was detected in genotypes containing Ryadg and other Ry genes. Some signals with ADG2 were also observed in other species within family Solanaceae inferring with the diversity of the corresponding chromosome region(s) among solanaceous species.

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