Further characterization of tulip severe mosaic virus supports classification as a member of genus Ampellovirus in the family Closteroviridae

Tulip bulb and flower production greatly contribute to the economy in The Netherlands. However, severe loss in this industry is caused by different viruses. In recent years, diagnostic tools were developed for most of these viruses with Tulip severe mosaic virus (TSMV) as one of the few exceptions. To further characterize TSMV, the virus was amplified by reverse transcription-polymerase chain reaction (RT-PCR) with degenerate primers targeted to conserved sequences of the Heat shock protein 70 gene of viruses from the family Closteroviridae. Phylogenetic analysis of the 0.5 kb HSP70 gene fragments showed that TSMV is closely related to Plum bark necrosis stem pitting-associated virus (PBNSPaV), Apricot stem pitting-associated virus (ASPaV) and Pineapple mealybug wilt-associated virus 1 (PMWaV-1), all three members of the genus Ampellovirus. In addition, a set of primers amplifying a TSMV-specific fragment was designed that enables fast and specific detection of the virus. Additionally to the molecular experiments, two possible modes of virus transmission were tested, viz. by aphids and by soil-borne organisms. However, no transmission was recorded by both methods.