Identification of Resistance Gene to PVY and Its Relation to Marketable Tuber Yield of PVY Resistant Potato Genotypes

In this study, the Rysto gene, originaly found in wild potato (Solanum stoloniferum), confers extreme resistance against PVY. It was identified in 21 potato clones and varieties and they were evaluated for some agronomic traits. For this purpose five trials were conducted. In first trial 320 potato genotypes were planted on the farm and 55 symptomless clone and cultivars were selected. In second trial, 55 genotypes along with sensitive control genotype (Desireh) were planted in 20 cm pots in the greenhouse at 15-20 °C with three replications. After five weeks, upper leaves were infected artificially with sap from tobacco fresh leaves checked for infection with PVYNTN and additional infections were repeated after 48 hours. Symptoms were recorded and all plants were tested by enzyme-linked immunosorbent assay (ELISA) about 4 weeks after inoculation. Plants that showed visual symptoms or/and gave at least a positive ELISA result were considered as susceptible and symptomless response with negative ELISA results were considered as resistant. In third trial, 23 genotypes were planted in the greenhouse and the PVY infected young tobacco shoots were grafted to symptomless genotypes with negative ELISA results with three replications and were selected as resistance genotypes. In fourth trial, all the PVY resistant genotypes were checked by molecular marker (STM0003) for detection of Rysto gene. Finally four potato varieties (Jelly, Sante, White Lady and Savalan cultivars) and 19 advanced clones were regarded as carriers of Rysto gene. In the fifth experiment genotypes were evaluated for marketable tuber yield of varieties and clones resistant to virus PVY in field conditions and 397009-8 clone was selected as high-yielding and tolerant genotype to PVY virus. Also, This clone did also have appropriate quality traits like oval-round tuber shape, uniform tubers, short stolon length, light yellow flesh color, yellow skin color, good tuber dry matter percent, tuber flesh texture of relatively soft (multipurpose) and shallow depth tuber eye.