High genetic stability of potato yellow mosaic Panama virus infecting tomato in Panama

The relevant regions in Panama involved in commercial tomato production, including the Chiriquí, Veraguas, Herrera, Los Santos and Panama Oeste provinces, were surveyed for the distribution and genetic diversity of potato yellow mosaic Panama virus (PYMPV) in the growing seasons of 2011 and 2012. A total of 28 tomato plots were surveyed and 314 individual tomato plants were sampled. DNA was extracted from each plant for a subsequent rolling circle amplification (RCA) analysis, to confirm the presence of begomovirus infections. The samples displaying a positive RCA reaction were subsequently analysed by PCR with a specific primer pair to identify PYMPV. This virus was detected in samples collected in all the above-mentioned provinces. The population structure of PYMPV was assessed by single-strand conformation polymorphism (SSCP) analysis. In total, four distinct SSCP patterns were distinguished. Based on the geographical distribution and the different patterns obtained, 42 viral isolates were selected for cloning and sequencing. Sequences obtained were compared with the ancestral sequence of PYMPV reported in Panama in 1998. These sequences showed very low variability, with two lineages probably originated by a single introduction.