Screening of Russian potato cultivars (Solanum tuberosum L.) with DNA markers linked to the genes conferring extreme resistance to potato virus Y

Potato Solanum tuberosum L. is infected by about 40 species of viruses, of which one of the most harmful is the potato virus Y (PVY). Crop losses of PVY susceptible cultivars can reach 80 %. At present, marker-assisted selection (MAS) using DNA markers linked to the Ry genes is widely used to create varieties highly resistant to PVY. MAS increases breeding efficiency and also allows one to assess the genetic protection or vulnerability of the variety' gene pool. A number of genes conferring different types of PVY resistance have been identified in potato, of which Ry genes, conferring extreme resistance (the absence of accumulation of viruses in infected plants regardless of the virus strain), are most often involved in breeding programs in different countries. The search for effective markers of target genes remains relevant due to MAS prospects. This paper is the first report on the use of STM0003 marker associated with Rysto gene for screening Russian potato varieties; another marker, Ry364, was previously used once on a small sample of Russian varieties. The objective of this work was to screen 178 Russian varieties with three markers, STM0003, Ry364, and RYSC3 linked to Rysto , Rychc , and Ryadg genes which were introgressed into the breeding gene pool from wild species S. stoloniferum , S. chacoense , and from the Andean native varieties of S. tuberosum ssp. andigenum, respectively. As a result of the molecular screening, 39 (21.8 %) of 178 varieties were selected for which diagnostic fragments of at least one of the three markers were revealed, including 7.3 % varieties with STM0003 marker ( Rysto ), 11.7 % varieties with Ry364 ( Rychc ), and 4.5 % varieties with RYSC3 ( Ryadg ) marker. The results obtained indicate a low level of genetic defense against PVY of the analyzed cultivar subset among which 78.2 % varieties have no markers linked to the Ry genes. We compared molecular screening results with published PVY resistance/susceptibility data. The marker STM0003 linked to the Rysto gene had the highest diagnostic value, as almost all varieties with this marker are highly resistant (immune) to PVY, while the Ry364298 and RYSC3 markers are not so efficient.