Extreme resistance to Potato Virus Y in potatoes of the German variety list

Abstract

Potato virus Y is the most important virus for potato economy. The breeding of virus resistant potato cultivars seems to be the only potent strategy against PVY infection. Beside hypersensitivity, extreme resistance to PVY is the most effective kind of resistance. At present this trait is verified in more than 20 Solanum-varieties which were used in different amounts in the breeding process. For S. stoloniferum (Ry_sto), S. tuberosum ssp. andigena (Ry_adg) and S. chacoense (Ry_chc) PCR markers for marker assisted selection to extreme resistance are already described in literature. The Ry_sto marker was present in 21 from 31 extreme resistant potato cultivars of the German assortment which were selected by grafting. The other 10 cultivars were also not selectable by Ry_adg. Because most of these cultivars were male fertile, we assume that other resistance genes from S. stoloniferum, maybe Ry_sto^na or Ry_stoⁿ¹, were used in their breeding process. These genes are not associated, in contrast to Ry_sto, with male sterility and mitochondria of the γ-type. Further investigations are necessary to prove this hypo­thesis and to establish molecular selection methods also for these resistance genes in order to ease the resistance test methods.