Molecular characterization and Phylogenetic analysis of Turnip mosaic virus (TuMV) in Erysimum linifolium L. in Italy

In the Summer of 2012, Erysimum linifolium L. pot plants produced at an ornamental grower in Liguria region (northern Italy), showed unusual virus-like disease of dark mottle and stripes on mauve-purple petals. A virus was mechanically transmitted from symptomatic flowers to several test plant species belonging to Chenopodiaceae and Brassicaceae families. This virus was identified as an isolated of turnip mosaic virus (TuMV) by PAS-ELISA analysis, electron microscopy negatively stained crud extracts and immuno-electron microscopy (IEM) tests. In the naturally infected E. linifolium plants, TuMV occurred alone, since any other viruses either by electron microscopy or mechanical inoculations were detected. By applying RT-PCR a fragment of 862 bp was amplified corresponding to all coat protein (CP). The comparison of CP gene showed no correlations between their genetic variation and geographical origins. The diversity in southern Europe appeared very low, most likely due to the rapid growth of TuMV in relation to trade between different Countries. The consequent exchange of infected propagation material shows that some lineages are adapted to particular crop species, and that recombination is a significant generator of the genetic diversity in populations of this virus. This is the first report of TuMV in E. linifolium worldwide.