Occurrence and Molecular Characterization of Recombinant Potato virus Y Isolates from Sulawesi, Indonesia.

The importance of potato has increased dramatically in Indonesia over the last three decades. During this period, 'Granola', a potato cultivar originally from Germany, has become the most common cultivar for fresh consumption in Indonesia. In August 2014, a survey was conducted in Sulawesi, where potato fields cultivated with Granola and its selection, 'Super John', were sampled for Potato virus Y (PVY) presence. PVY was found in Sulawesi for the first time. Samples determined to be positive for PVY were subsequently typed to strain using reverse-transcription polymerase chain reaction assays. All PVY isolates sampled were identified as PVY recombinants, with three recombination junctions in P3, VPg, and CP regions of the genome. Three local PVY isolates were subjected to whole-genome sequencing and subsequent sequence analysis. The whole genomes of the Indonesian PVY isolates I-6, I-16, and I-17 were found to be closely related to the European PVY-A. This recombinant type was shown previously to cause potato tuber necrotic ringspot disease (PTNRD) in susceptible potato cultivars. The dependence of potato farmers on mostly a single cultivar, Granola, may have given a competitive advantage to PVY over other PVY strains, resulting in the predominance of the PVY recombinant. The dominance of PVY in Sulawesi, and possibly in Indonesia as a whole, represents a potential risk to any newly introduced potato cultivar to the country, especially cultivars susceptible to PTNRD.