The virome of Freesia hyb. showing leaf necrosis syndrome

Ornamental plants constitute a largely unknown and important source of pathogens potentially able to affect also major crop species. For this reason, known and still unknown viruses of ornamental plants able to produce heavy damage cannot be a priori considered as 'second-class' viruses. The leaf necrosis syndrome of freesia was first described in freesia crops in the Netherlands before 1970 and it is still jeopardizing freesia cultivations all over the world, producing heavy symptoms. The etiological agent of this syndrome is still not fully elucidated, but it was tentatively identified in the ophiovirus freesia sneak virus (FreSV). Since their development, Next Generation Sequencing (NGS) technologies have been demonstrated to be particularly useful to investigate the plant associated viromes, being able to reveal the presence of all viral agents, including still unknown entities. Here, we have carried out total RNAs NGS-based characterization of viruses present in freesia plants showing strong necrotic symptoms, collected in different years in a farm located in Northern Italy. The necrotic freesia associated virome was reconstructed using an ad hoc bioinformatics pipeline, mainly addressing the new viral species discovery. Results, validated by independent molecular methods, seem to underline a simple but interesting scenario, comprising old and new actors on this stage: among which we find FreSV, the still uncharacterized phlebo-like virus, and the potyvirus freesia mosaic virus (FreMV).