NEW FEATURES IN THE VIROME OF FREESIA HYB. SHOWING LEAF NECROSIS SYNDROME IDENTIFIED BY AN NGS-BASED OMICS APPROACH

The necrosis syndrome of freesia was first described before 1970 in Northern Europe, and it is still jeopardizing freesia cultivation all over the world, producing severe symptoms. Different viruses have been suggested as possible causal agent, but, until now, none of them have been convincingly associated with the disease. The ophiovirus freesia sneak virus (FreSV) has been proposed as the causal agent of the necrotic disease in Europe, USA, New Zealand, and South Korea, but the correlation between symptoms and the presence of FreSV was not clearly shown. Here we applied a next generation sequencing (NGS) based approach to investigate the virome associated to the necrosis syndrome of freesia and the possible involvement of other viral agents in the etiology of this disease. Freesia plants showing strong necrotic symptoms were collected in different years in Northern Italy and associated virome was reconstructed using an ad hoc bioinformatics pipeline. Results, validated by independent molecular methods, enlarged our knowledge of the virome of freesia, highlighting new features for known and new viral entities; among them a new genome component of FreSV, and an uncharacterized virus, likely belonging to a new family in the Bunyavirales order, as suggested by the Serratus-mediated comparison with sequencing data available at the NCBI Sequence Read Archive database.