Resistance of potato clones to necrotic recombinant strains of potato virus y (PVY)

Abstract

The Ryadg allele is widely used by breeders to confer extreme resistance to all strains of PVY. However, the necrotic strain has increased recombination resulting in recent considerable losses in productivity. Thus far, not all necrotic recombinant strains of PVY have been tested for their reaction to the Ry gene. The objective of this study was to identify potato clones carrying the resistant allele and to assess their reaction to the following recombinant strains: NTN (PVYNTN), Wilga (PVYN-Wi), and "curly top" (PVYE). Advanced clones from the potato breeding program at Universidade Federal de Lavras were evaluated through a specific molecular marker for the Ryadg allele. The clones carrying the resistance allele were grafted on tobacco plants infected with necrotic recombinant strains of PVY. The clones carrying the allele for resistance to PVY were not infected with any of the recombinants during the grafting test. These results confirm that resistance to necrotic recombinant strains has not yet been overcome and that the Ryadg allele also confers resistance to the three recombinant strains tested.