Background In agroecosystems, viruses are well known to influence crop health and some cause phytosanitary and economic problems, but their diversity in non-crop plants and role outside the disease perspective is less known. Extensive virome explorations that include both crop and diverse weed plants are therefore needed to better understand roles of viruses in agroecosystems. Such unbiased exploration is available through viromics, which could generate biological and ecological insights from immense high-throughput sequencing (HTS) data. Results Here, we implemented HTS-based viromics to explore viral diversity in tomatoes and weeds in farming areas at a nation-wide scale. We detected 125 viruses, including 79 novel species, wherein 65 were found exclusively in weeds. This spanned 21 higher-level plant virus taxa dominated by Potyviridae, Rhabdoviridae, and Tombusviridae, and four non-plant virus families. We detected viruses of non-plant hosts and viroid-like sequences and demonstrated infectivity of a novel tobamovirus in plants of Solanaceae family. Diversities of predominant tomato viruses were variable, in some cases, comparable to that of global isolates of the same species. We phylogenetically classified novel viruses and showed links between a subgroup of phylogenetically related rhabdoviruses to their taxonomically related host plants. Ten classified viruses detected in tomatoes were also detected in weeds, which might indicate possible role of weeds as their reservoirs and that these viruses could be exchanged between the two compartments. Conclusions We showed that even in relatively well studied agroecosystems, such as tomato farms, a large part of very diverse plant viromes can still be unknown and is mostly present in understudied non-crop plants. The overlapping presence of viruses in tomatoes and weeds implicate possible presence of virus reservoir and possible exchange between the weed and crop compartments, which may influence weed management decisions. The observed variability and widespread presence of predominant tomato viruses and the infectivity of a novel tobamovirus in solanaceous plants, provided foundation for further investigation of virus disease dynamics and their effect on tomato health. The extensive insights we generated from such in-depth agroecosystem virome exploration will be valuable in anticipating possible emergences of plant virus diseases and would serve as baseline for further post-discovery characterization studies.

Viruses influence plants in agroecosystems, where their pathogenic nature in crops is primarily studied. Within the same systems, their diversity in non-crop plants and role outside the disease perspective is less known. To better understand their diversity and ecology, we performed an extensive virome exploration focusing on tomatoes and diverse weed species within or surrounding tomato farms. We detected 126 viruses, wherein 80 were novel (70 exclusively from weeds), and demonstrated infectivity of a novel tobamovirus in solanaceous hosts. Diversities of predominantly detected tomato viruses were variable, in some cases, with patterns comparable to global isolates of same species. We phylogenetically analyzed and taxonomically classified novel viruses and showed links between a subgroup of phylogenetically-related rhabdoviruses and a group of taxonomically-related host plants. Around one-third of viruses (n=10) detected in tomatoes were also detected in weeds, which might indicate possible role of weeds as inoculum reservoirs. We showed that even in a relatively well studied agroecosystem, a large part of plant viromes can still be unknown. Extensive biological and ecological insights generated from such holistic agroecosystem virome exploration will aid in anticipating possible emergences of plant virus diseases, and would serve as baseline for post-discovery characterization studies.

Pepper (Capsicum annuum) and Tomato (Solanum lycopersicum) plants showing virus-like disease symptoms were collected in 2017, 2019, and 2020, in different parts of Slovenia (Supplementary Figure 1). Total RNA was extracted from leaf tissue of individual samples using RNeasy Plant Mini kit (Qiagen) and pooled in four composite samples as follows: 2 pepper plants from 2017 (D2017), 5 pepper and 4 tomato plants from 2019 (D2019_P1), 7 tomato plants (D2020_P1), and 2 pepper and 4 tomato plants (D2020_P3) from 2020. The pooled RNA samples were sequenced using Illumina platforms, details of the sequencing experiments are in Supplementary Table 1. Reads were analyzed using CLC Genomics Workbench (v. 20.0, Qiagen) following the pipelines for plant virus discovery (Pecman et al., 2017). Reads and contigs mapping to Ranunculus white mottle ophiovirus (RWMV, GenBank accession no. AY542957 or NC_043389) were detected in all pools. The longest contig (1,255 bp) was obtained from the 2019 composite sample, mapping to the coat protein-coding RNA 3 segment of the RWMV genome (accession no. AY542957). Details of mapping, genome coverage, and other viruses detected in the pools are summarized in the Supplementary Table 1. To identify individual RWMV-infected plants from the pools, primers were designed for detection by reverse transcription-polymerase chain reaction (RT-PCR) targeting the coat protein gene (see Supplementary Table 2). Two pepper samples from two different farms, collected in 2017 and 2019 in southwest Slovenia, and four tomato samples from two different farms, collected in 2020 in central Slovenia tested positive for RWMV in RT-PCR assays. To assess the diversity of RWMV isolates, amplicons were purified using QIAquick PCR purification kit (Qiagen) and sent for Sanger sequencing. Based on maximum likelihood phylogenetic analysis, RWMV Italian and Slovenian isolates form a monophyletic clade within the genus (see Supplementary Figure 2). Pairwise nucleotide identities of the Slovenian isolates (accession no. MZ507604-MZ507609), relative to the original Italian isolate coat protein (accession no. AY542957) range from 92-97%, indicating a moderate level of diversity among isolates (see Supplementary Figure 2). Since only RWMV, bell pepper alphaendornavirus (BPEV), and pepper cryptic virus 2 (PepCV2), were present in a pepper sample from 2017, and BPEV and PepCV2 infection in pepper are not known to be associated with any of the disease symptoms (Okada et al., 2011; Saritha et al., 2016), the symptoms observed on this plant might be associated with RWMV infection. We observed mottling with interveinal chlorosis or yellowing, slight to full curling of leaves from lamina inward, as well as necrotic and aborted flowers on this plant (see Supplementary Figure 1). We cannot easily associate observed symptoms with RWMV in RWMV-positive tomatoes, since several viruses were detected in the pools containing these samples. Nevertheless, the prominent symptoms in tomato were mottling with interveinal chlorosis and leaf curling, similar to those observed in pepper. RWMV was discovered and characterized in buttercup (Ranunculus asiaticus), and detected in anemone (Anemone coronaria), from Italy (Vaira et al., 1996, 1997, 2000, 2003). It was recently detected in pepper from Australia showing veinal yellowing (Gambley et al., 2019). Here, we detected RWMV for the first time in Slovenia, and reported its first detection in tomato and pepper from Europe. These findings call for further studies on the effects of RWMV infection on tomato and pepper production, and its monitoring in neighboring European countries. Acknowledgment This study received funding from the Administration of the Republic of Slovenia for Food Safety, Veterinary Sector and Plant Protection, Slovenian Research Agency (ARRS) core financing (P4-0165), and the Horizon 2020 Marie Skłodowska-Curie Actions Innovative Training Network (H2020 MSCA-ITN) project “INEXTVIR” (GA 813542), under the management of the European Commission-Research Executive Agency. References Gambley, C., et al. 2019. New Dis. Rep. 40:13. doi:10.5197/j.2044-0588.2019.040.013. Okada, R., et al. 2011. J. Gen. Virol. 92:2664-2673. doi:10.1099/vir.0.034686-0. Pecman, A., et al. 2017. Front. Microbiol. 8:1-10. doi:10.3389/fmicb.2017.01998. Saritha, R. K., et al. 2016. VirusDisease 27:327-328. doi:10.1007/s13337-016-0327-7. Vaira, A. M., et al. 2003. Arch. Virol. 148:1037-1050. doi:10.1007/s00705-003-0016-x. Vaira, A. M., et al. 1996. Acta Hortic., 432:36-43. doi:10.17660/ActaHortic.1996.432.3. Vaira, A. M., et al. 1997. Arch. Virol. 142:2131-2146. doi:10.1007/s007050050231. Vaira, A. M., et al. 2000. Plant Dis. 84:1046-1046. doi:10.1094/PDIS.2000.84.9.1046B.

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Tancik J., Seljak G. (2017): Occurrence of Scaphoideus titanus Ball and some other Auchenorrhyncha in the vineyards of western Slovakia. Plant Protect. Sci., 53: 95-100.A study of Auchenorrhyncha was carried out in 2014 and 2015 in 7 vineyard plots with different varieties and pest management strategies in the Nitra wine region and Lesser Carpathian wine region in western Slovakia. The aim of this study was to obtain information related to the presence of potential vector insects associated with grapevine yellows phytoplasmas from the Flavescence dorée and Bois noir groups. Insects were collected by sweeping with an entomological net. Thirty species of Auchenorrhyncha were identified as belonging to 6 families. Cicadellidae were the most abundant, comprising 20 species. Scaphoideus titanus was collected at 4 localities. Identification of the phytoplasma vector is critical to the national strategy for assessment and control of vectors spreading the phytoplasma disease in Slovakian vineyards. The first finding of Metcalfa pruinosa was noticed in vineyards in Slovakia.