Characterization of potato and tobacco isolates of Cucumber mosaic virus from Syria and the first report on CMV satellite RNA from potato

Cucumber mosaic virus (CMV) has been reported from potato production areas in Europe, USA, Japan and more frequently in regions with warm climates such as Egypt, India, Saudi Arabia and Syria. As it is considered as an uncommon virus in potato, the characterization of potato isolates of CMV is far behind those from other hosts. In addition to potato, CMV is a common virus infecting many crops in Syria, but nothing is known about its molecular characteristics. The present study aimed to characterize Syrian CMV isolates collected from potato and neighboring tobacco fields. All potato isolates of CMV (total of four) co-infected potato plants with Potato virus Y (PVY) which is the most frequent potato virus in Syria. According to the sequence analyses of the coat protein (CP) coding region, three potato and three tobacco CMV isolates were found to be closely related regardless of the host species or geographic origin, and all belonged to the IA strain subgroup of CMV. A potato CMV isolate, PoCMV7-5, readily infected solanaceous plants in which it induced systemic infection, but was less infectious to other hosts including those of Leguminosae and Cucurbitaceae. When inoculated on potato plants, PoCMV7-5 alone or with various PVY strains was able to cause local but not systemic infection in all potato cultivars inoculated. PoCMV7-5 contained heterogeneous variants of satellite RNA which varied in length due to A or/and T deletion/insertion at approximate nucleotide position 225‒240. This is the first report on CMV satellite RNA from potato.