Combining resistance to potato leafroll virus (PLRV) with immunity to potato viruses X and Y (PVX and PVY)

Summary Degeneration of seed tubers caused by viruses is a major constraint to potato cultivation in many warm tropical areas. Cultivars resistant to the most important viruses present a promising solution to such a problem. In a breeding study conducted at the International Potato Center (CIP), ten cultivars resistant to PLRV were crossed to five clones immune to PVX and PVY, as well as to a susceptible control. The resulting progenies were screened for PVX and PVY immunity. Afterwards, the resistant genotypes were fieldexposed to a PLRV-viruliferous aphid population. One tuber was harvested from each plant and used to assess, using ELISA serology, the presence of leafroll virus. The cultivars Serrana and Pentland Crown gave the best progenies in terms of percentage of healthy plants, with values of 47.4 and 33.3 respectively. The presence of joint infection of PLRV and PVY or PVX in the progenies of the susceptible control resulted in an increased susceptibility to leafroll.