Diversity and pathobiology of an ilarvirus unexpectedly detected in diverse host plants and in global sequencing data

Abstract

ABSTRACTHigh-throughput sequencing (HTS) and sequence mining tools revolutionized virus detection and discovery in recent years and implementing them with classical plant virology techniques results to a powerful approach to characterize viruses. An example of a virus discovered through HTS is Solanum nigrum ilarvirus 1 (SnIV1) (familyBromoviridae), which was recently reported in various solanaceous plants from France, Slovenia, Greece, and South Africa. It was likewise detected in grapevines (Vitaceae) and severalFabaceaeandRosaceaeplant species. Such a very diverse host association is atypical for ilarviruses, thus warranted further investigation. In this study, modern and classical virological tools were combined to accelerate the characterization of SnIV1. Through HTS-based virome surveys, mining of sequence read archive datasets, and literature search, SnIV1 was further identified from diverse plant and non-plant sources globally. SnIV1 isolates showed relatively low variability compared to other phylogenetically related ilarviruses. Phylogenetic analyses showed a distinct basal clade of isolates from Europe, while the rest formed clades of mixed geographic origin. Furthermore, systemic infection of SnIV1 inSolanum villosumand its mechanical and graft transmissibility to solanaceous species were demonstrated. Near identical SnIV1 genomes from the inoculum (S. villosum) and inoculatedNicotiana benthamianawere sequenced, thus partially fulfilling Koch’s postulates. SnIV1 was shown to be seed-transmitted and potentially pollen-borne, has spherical virions, and possibly induces histopathological changes in infectedN. benthamianaleaf tissues. Overall, this study provided information to better understand the diversity, distribution, and pathobiology of SnIV1, but whether it could emerge as a destructive pathogen remains uncertain.FundingEU Horizon 2020 Marie Skłodowska-Curie Actions Innovative Training Network (H2020 MSCA-ITN) project no. GA 813542Administration of the Republic of Slovenia for Food Safety, Veterinary Sector and Plant Protection and Slovenian Research Agency (ARRS) funding no. P4-0165, P4-0407, J4-4553Balik Scientist Program (Republic Act 11035) of the Department of Science and Technology– Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development (DOST–PCAARRD), Republic of the PhilippinesThe Belgian FPS Health Food Chain Safety and Environment under Project RT18/3 SEVIPLANT