Evaluation of a SCAR RYSC3 Marker of the Ry adg Gene to Select Resistant Genotypes to Potato Virus Y (PVY) in the INIA Potato Breeding Program

Abstract

The Potato virus Y (PVY) is distributed worldwide and is one of the most damaging viruses in terms of yield reduction in the potato (Solanum tuberosum L.) crop with losses sometimes reaching 80%. To reduce its impact, there is great interest in obtaining varieties carrying the Ryadg gene that provides extreme resistance to this virus. This could be facilitated with SCAR (sequence characterized amplified region) RYSC3 by molecular marker-assisted selection (MAS). This study compared the effectiveness of the RYSC3 marker in the detection of the Ryadg gene vs. biological tests on populations of the Potato Breeding Program of the Instituto de Investigaciones Agropecuarias (INIA), Chile. Within the group of 71 progenitors, 30 plants had some kind of resistance to the virus, of which 17 were carriers of the RYSC3 marker. These genotypes came from Cornell University, Centro Internacional de la Papa (CIP), Peru, and INIA. The analysis of 460 progenies which came from three different crosses showed that 299 individuals amplified the RYSC3 marker and had the resistant phenotype, with the exception of one plant. Within the group of non-RYSC3 carrier plants, a significant percentage (22.5%) showed a resistant phenotype, indicating that these progenies segregate other R genes (e.g., hypersensitivity) that reduce biological test effectiveness. This high effectiveness (99.7%) in the detection of the Ryadg gene in both parents and segregating progenies, showed that this marker is appropriate in assisting selection of genotypes with extreme PVY-resistance in the potato breeding programs.

Validation of molecular markers for pathogen resistance in potato

“…Similar results were obtained by Sagredo et al. () with this marker. In genotypes carrying the PVY resistance gene Ry sto introgressed from S. stoloniferum, the presence of a 564‐bp EcoRV restriction fragment was reported in all cases (Witek et al.…”

“…According to Kasai et al (2000), SCAR marker RYSC3 cosegregates perfectly with Ry adg and represents a diagnostic tool to detect extreme resistance (ER) to PVY. Similar results were obtained by Sagredo et al (2009) with this marker. In genotypes carrying the PVY resistance gene Ry sto introgressed from S. stoloniferum, the presence of a 564-bp EcoRV restriction fragment was reported in all cases (Witek et al 2006).…”

Identification of virus and nematode resistance genes in the Chilota Potato Genebank of the Universidad Austral de Chile

“…The utilization of the RYSC3 marker has been validated by many authors such as Dalla Rizza et al (2006), Sagredo et al (2009), Veramendi et al (2011), Ortega and Lopez-Vizcon (2012), and Lopez-Pardo et al (2013. In the evaluation of the 271 Solanum tuberosum subsp.…”

“…These represent a 95% correlation between molecular and serological results. Both methods are usually applied as a tool for virus resistances evaluations; like Gebhardt et al (2006), Sagredo et al (2009), andOrtega andLopez-Vizcon (2012). The remaining 148 accessions showed no virus infection and no molecular marker amplification, task that might be explained by unknown PVY resistance sources, since that plant has been exposed to natural pest presence on the field.…”

“…The PCR program consisted of an initial denaturation step at 93 °C for 9 min, followed by 35 cycles of denaturation at 95 °C for 45 s, primer annealing at 52 °C for 45 s and primer extension at 72 °C for 1 min, followed by a final extension at 72 °C for 10 min. The negative control used was 'Desiree' (susceptible to PVY) and the positive control used was 'Eva' that possesses the Ry adg gene and is immune to PVY, as described in Sagredo et al (2009). According to the protocol described by Song and Schwarzfischer (2008), the Ry sto gene was detected using the YES3-3B STS marker.…”