Molecular Analysis of the Coat Protein of Potato virus Y Isolates in Greece Suggests Multiple Introduction from Different Genetic Pools

Abstract

The phylogenetic relationships among Potato virus Y (PVY) isolates from northern and southern Greece were investigated. A large part of coat protein gene of 49 tobacco isolates and three from pepper was examined. The analysis showed that all 52 isolates consisted of 34 distinct haplotypes, with only one haplotype found in both northern and southern regions. The southern population was more diverse than that from the north. The phylogenetic analyses of the Greek haplotypes alone or in combination with isolates from other countries using the maximum likelihood method classified unambiguously almost all the haplotypes examined. Nine tobacco haplotypes from the south were classified as C-like (particularly C1), whereas 22 haplotypes from tobacco and two from pepper from both north and south were classified as N-like. One tobacco haplotype from the south was found recombinant between N-like and C1 lineages. The pattern of molecular evolution was examined using the fixed-effects likelihood and the single-likelihood ancestor counting methods. The analysis indicated that the evolution of PVY isolates appeared to be conservative (purifying selection and neutral evolution). These findings are discussed in relation to the introduction of PVY in the tobacco crop in Greece and the between region dispersal. A scenario of multiple introductions of PVY isolates in north and south Greece from different genetic pools and low or nil between region spread of the virus isolates was proposed.