Nucleotide sequence analysis reveals the presence of PVY-Tam isolates affecting tamarillo in Colombia

1.Tamarillo or tree tomato (Solanum betaceum Cav.) is a fruit tree species of Andean origin with cultural and economic relevance in Colombia. However, the high incidence of complex viral diseases termed "virosis" in all tamarillo-growing regions of the country leads to huge production losses and seriously threatens its cultivation. The lack of effective treatments implies eradication as the only alternative in severe cases. In this work, we characterized the virome of eight tamarillo-growing locations across the Department of Narino (Colombia). By in-depth sequence analysis of RNA libraries, we confirmed the presence of up to four different virus species belonging to the genera Torradovirus, Potyvirus and Polerovirus in symptomatic tamarillo plants. These results represent the first report of torradovirus infection in tamarillo. Additionally, we identified a novel isolate of potato virus Y-Tamarillo (PVY-Tam) in Narino that could have originated in South America by a recent divergence of the PVYN lineage. We propose that length variability in the P3N-PIPO protein, which in the case of PVY-Tam contains two premature stop codons not identified in other PVY isolates, might be involved with host-specific adaptations. Our findings broaden the knowledge of tamarillo virosis in the Andean region, and overall, worldwide, thus offering new possibilities for developing effective diagnostic and control strategies.