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COVID-19, which broke out globally in 2019, is an infectious disease caused by a novel strain of coronavirus, and its spread is highly contagious and concealed. Environmental vectors play an important role in viral infection and transmission, which brings new difficulties and challenges to disease prevention and control. In this paper, a type of differential equation model is constructed according to the spreading functions and characteristics of exposed individuals and environmental vectors during the virus infection process. In the proposed model, five compartments were considered, namely, susceptible individuals, exposed individuals, infected individuals, recovered individuals, and environmental vectors (contaminated with free virus particles). In particular, the re-positive factor was taken into account (i.e., recovered individuals who have lost sufficient immune protection may still return to the exposed class). With the basic reproduction number R 0 of the model, the global stability of the disease-free equilibrium and uniform persistence of the model were completely analyzed. Furthermore, sufficient conditions for the global stability of the endemic equilibrium of the model were also given. Finally, the effective predictability of the model was tested by fitting COVID-19 data from Japan and Italy. [ABSTRACT FROM AUTHOR]

Grapevine 'Pinot gris' virus (GPGV) is a newly emergent virus associated with the appearance of grapevine leaf mottling and deformation disease (GLMD). The worldwide spreading of this virus, and sometimes of the associated disease, that has occurred in the last years, requests further epidemiological studies to verify the progress of natural infection in the field. In the present paper, GPGV infection and spatiotemporal spreading of GLMD, investigated in two vineyards with high disease occurrence, confirmed an elevated presence of the virus in vineyards of Northeastern Italy, and revealed an increasing of symptomatic plants over the time. At the same time, the progress of natural infection was monitored after the placement of new grafted plants near the symptomatic grapevines in the infected vineyards. After three years, 76 % of the plantlets that were initially GPGV-free became GPGV-infected, giving an evidence of the fast transmission of GPGV in the field. Only 14 % of the plantlets, all collocated inside a patch with diseased plants, showed typical GLMD-symptoms. Interestingly, some plantlets, which were already GPGV-infected with the "asymptomatic" GPGV variant before planting in the field, did not become infected with the "symptomatic" viral wild variant after three years and never showed GLMD symptoms. [ABSTRACT FROM AUTHOR]

Wisteria vein mosaic virus (WVMV) is a potyvirus infecting Wisteria spp. worldwide, making these largely used ornamental plants unattractive and even unsalable. In 2021, nine Wisteria sinensis plants in Sarzana (Liguria, Italy) showing WVMV symptoms like vein mosaic with irregular patterns, mottling, deformation and twisting margin on leaves were reported. This work describes research on symptomatic and asymptomatic leaves to confirm the identity of the virus infection. All plants tested resulted positive to WVMV. Sequencing of NIb/CP genomic region and comparison on GenBank revealed the presence of eight new genetic variants named Sar 5–12. The eight nucleotide sequences alignments revealed identity ranging between 87.13 and 99.85%. Negative selection (dN/dS < 1) was detected suggesting well adaptation in the area here examined and stability in population. Through a phylogenetic tree, WVMV isolates were grouped in four clades with high bootstrap values, two of which included the eight Italian variants here identified. Since the late 1950 and 1960s, the present study represents the first additional report of WVMV in Italy, as well as its first molecular characterization ever. Further research is required to strengthen our understanding of the movement and transmission of WVMV. Examining how virus infected plants can disseminate this pathogen could help forestall potential risks that neighbouring species may face in their environments. [ABSTRACT FROM AUTHOR]

Two dsRNAs from cherry trees affected with cherry chlorotic rusty spot (CCRS) in Italy and Amasya cherry disease (ACD) in Turkey were sequenced and found to be essentially identical. The larger dsRNA 1 (2021 or 2006 bp, respectively) potentially encoded a protein of 621 aa containing the conserved motifs of the RNA-dependent RNA polymerases (RdRp) of dsRNA mycoviruses, having highest similarity with those in the genus Partitivirus. The smaller dsRNA 2 (1841 or 1839 bp, respectively) had properties consistent with the second genomic component of a partitivirus and potentially encoded the coat protein (CP) of 504 aa. Phylogenetic analysis based on the RdRp and CP was coincidental and indicated that species in the genus Partitivirus could be separated into two subgroups. Because species of this genus only infect fungi, these observations suggest a fungal aetiology for CCRS and ACD, further substantiating a previous proposal (see accompanying paper by Covelli et al., 2004, in this issue).

Since its discovery in 2012, the role of the trichovirus named grapevine Pinot gris virus (GPGV) as the causative agent of grapevine leaf mottling and deformation (GMLD) syndrome, a grapevine disease for which symptoms had been observed in north Italy and western Slovenia a few years earlier, has been a matter of discussion. In the following 10 years of investigations, evidence has emerged of a role for the genetic diversity of the virus and for the varietal diversity of the host, as well as their interaction during antiviral defence (i.e. RNA silencing) and virus‐mediated defence suppression. In a context of wider research efforts, several relevant aspects of GPGV evolution and GMLD epidemiology were also clarified. Nevertheless, a complete understanding of the molecular events and the environmental conditions that could affect viral infection severity and symptom display remains a challenging puzzle. In the meantime, we are witnessing a large spread of the virus, which has almost completely permeated the regions where it first appeared, while spreading through most areas of grapevine cultivation. A deeper knowledge of the molecular context of the disease is key to establishing whether the impressive potential of GPGV to spread makes it a candidate as the next emerging threat for the grapevine industry. [ABSTRACT FROM AUTHOR]

Agrochemicals are generally used in agriculture to maximize yields and product quality, but their overuse can cause environmental pollution and human health problems. To reduce the off-farm input of chemicals, numerous biostimulant products based on beneficial symbiont plant fungi are receiving a great deal of attention. The evolution of plant diseases and the performance of insects are influenced by plant chemical defences, both of which are, in turn, influenced by below-ground symbionts. Direct and indirect plant defences mediated by belowground symbionts against plant diseases and insect herbivores were demonstrated in greenhouses experiments. However, little attention has been paid to the use of Trichoderma under open field conditions, and no data are available for zucchini (Cucurbita pepo L.) plants in the field. To determine the effects of a commercial Trichoderma harzianum strain T22 on plant viruses, powdery mildew, the arthropod community, and on the agronomic performance associated with zucchini plants, an experiment was conducted in 2022 under open field conditions in South Italy. Our results indicate that T. harzianum T22 makes zucchini plants more attractive to aphids and to Hymenoptera parasitoid but failed to control zucchini pathogens. The complex plant–disease–arthropod–microorganism interactions that occurred in the field during the entire plant cycle are discussed to enrich our current information on the possibilities of using these microorganisms as a green alternative in agriculture. [ABSTRACT FROM AUTHOR]

In this study, we analysed a total of 16 libraries from over 150 grapevine leaf and grape samples infected with Plasmopara viticola (downy mildew of grapevine) to characterise the virome associated to this oomycete. Samples were collected in five distinct regions in Italy and in four different regions in Spain, representative of different pedoclimatic conditions and different grapevine cultivars during 2018 growing season. Due to the metagenomics nature of the samples (containing at least both downy mildew hyphae and spores, and grapevine cells residues), we were able to assemble several plant viruses and a few possible novel plant virus genomes with our in silico analysis. We detected several plant virus variants already reported in grapevine, and a putative new ilarvirus previously unreported in grapevine. Furthermore, we characterised three new phenui‐like viruses (in the order Bunyavirales), one of which shares some commonalities with plant coguviruses. Finally, we report a new strict association of three viral segments (one flavi‐like and two virga‐like) that we propose to be a new virus taxon named jivivirus. [ABSTRACT FROM AUTHOR]

Garlic is an important crop cultivated worldwide and several different viruses have been associated with propagative material. Garlic is propagated from bulbs and/or from vegetative topsets of the inflorescences known as bulbils. The effects of the geographic origin and the type of the propagative material on the phylogenetic relationships and genetic variability of the coat protein genes of four allium viruses are presented here. Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV), Garlic virus X (GVX), and Garlic common latent virus (GCLV) were detected in single and mixed infections in plants grown either from bulbils and/or bulbs originating from Italy, China, Argentina, and the U.S.A. OYDV and LYSV fell into five and three well supported clades respectively whereas isolates of GVX and GCLV all clustered into one well-supported clade each. Some of the OYDV and LYSV clades presented evidence of host tissue selection while some phylogenetic structuring based on the geographic origin or host was also observed for some virus clades. Unique haplotypes and novel coat protein amino acid sequence patterns were identified for all viruses. An OYDV coat protein amino acid signature unique to Chenopodium quinoa, an uncommon host of the virus, was of particular interest. The type of propagative material affected the population dynamics of all of the viruses. The virus populations in plants propagated from bulbs were more diverse than in plants propagated from bulbils. [ABSTRACT FROM AUTHOR]

An abstract of the article "Sweet potato feathery mottle virus is the casual agent of sweetpotato virus disease in Italy" is presented. In early 2005, sweetpotato plants with virus-like symptoms were observed in many fields in Latina province. Diseased plants ranged from 30 to 60 percent. Initial symptoms consisted of vein clearing and leaf chlorotic spots, followed by general leaf yellowing, leafarea reduction, plant stunting, with a significant reduction of tuber size.

The article discusses the occurrence of Sweet potato leaf curl virus (SPLCV) in Catania, Sicily in Italy. In 199, cuttings of Ipomoea indica showing yellow vein symptoms were gathered in Catania. A clone of the begomoviruses associated with the disease was produced by polymerase chain reaction-mediated amplification. It was concluded that the isolate coming from Sicily is a strain of SPLCV which is provisionally designated SPLCV-Sicily. The presence of this begomovirus species in the country suggests that its geographical range extends further across the Mediterranean basin.

The article discusses the first report of a phytoplasma associated with abnormal proliferation of cladodes in cactus pear, Opuntia ficus-indica, in Italy. The cactus pears exhibited severe proliferation of cladodes with lack of flowers, fruits and spine production. Total DNA was extracted from both symptomatic and asymptomatic cactus pears. This was utilized as template for phytoplasma-specific 16S rDNA polymerase chain reaction amplification. The RFLP patterns acquired from analysis of rDNA amplicons were identical with the pattern obtained for reference strain faba bean phyllody phytoplasma.

Capparis spinosa plants in the Sicilian Islands, Italy, are frequently infected with Caper latent virus (CapLV). CapLV affects the vigour and longevity of caper plants and exacerbates the effect of other adverse biotic and abiotic factors. To have CapLV-free cuttings of caper for multiplication and new planting is therefore advantageous for a revival of this crop wherever it is cultivated. An improved procedure for the in vitro thermotherapy combined with the culture of the shoot tips of C. spinosa has been applied to caper material collected from Salina (Aeolian Archipelago) and Pantelleria. More than of 60% (Salina) and 90% (Pantelleria) of the shoot tips survived, and 89-93% of the regenerated plantlets were CapLV-free when tested by RT-PCR. This is the first report on eliminating CapLV from caper plants. [ABSTRACT FROM AUTHOR]

An unusual virus-like yellow leaf disorder associated with fruit marbling was observed during the winter of 2005 in some greenhouse tomato crops in the province of Ragusa Sicily (Southern Italy). Leaf samples from 250 symptomatic tomato plants were serologically tested by DAS-ELISA technique for 5 viruses: Tomato spotted wilt virus (TSWV), Impatiens necrotic spot virus (INSV), Tobacco mosaic virus (TMV), Cucumber mosaic virus (CMV) and Pepino mosaic virus (PepMV). PepMV was detected in 215 of the samples. The virus was mechanically transmitted to cucumber, wild metel, wild tobacco and 'Rio Grande' tomato. The experimental host range of PepMV-Ragusa differed from that of the PepMV found in Sardinia in 2001, which infected 'Camone' tomato. By applying RT-PCR to 25 PepMV-infected tomato plants, the expected 844 bp DNA fragment for PepMV and the expected 439 bp DNA fragment for Tomato chlororis virus (ToCV) were obtained from all the samples tested. Sequences of the obtained amplicons were used to study the phylogenetic relationships of the viruses with isolates from other countries. Nucleotide sequence alignments showed that the sequence CP-PepMV-Ragusa (Genbank acc. No. DQ 517884) were 99% homologous with both US2 and Spain-Murcia isolates, while those of ToCV-Ragusa (Genbank acc. No. DQ517885) isolate HSP70, were 99% homologous with the Florida isolate, and 98% with the Lebanon isolate. The results proved that the unusual disorder found in greenhouse tomatoes in Sicily can be associated with infections by PepMV and ToCV, reported for the first time in a mixed infection. [ABSTRACT FROM AUTHOR]

Examines the pepino mosaic virus in tomato in Italy. Presence of potexvirus-like particles in tomato fruits and leaves; Dissemination route of the virus; Use of antiserum in detecting the virus.

Abstract A one-step reverse transcription–polymerase chain reaction (RT–PCR) protocol was developed and used for the detection of Strawberry latent ring spot virus (SLRSV) in leaves of olive trees in Italy. The protocol was used to test for infection in samples from 87 trees and to correlate infection with leaf symptoms. SLRSV was found only in olives grown in Central Italy (the Marche and Umbria regions) and was detected in c. 15% of leaf samples. Most infected plants had narrow and twisted leaves, symptoms which seemed to occur in specific cultivars. The one-step RT–PCR protocol is very rapid and sensitive and has the potential to be used on a mass scale for the diagnosis of SLRSV in olive. This virus should be considered an important pathogen in olive trees, even if its distribution in the field seems to be limited to well defined areas. [ABSTRACT FROM AUTHOR]

Tomato yellow leaf curl Sardinia begomovirus (TYLCSV) appeared in Sicilia (IT) in 1988, creating great threats to agriculture and causing huge losses, especially in south-eastern areas of the island, where protected tomato cultivation is widespread. Towards the mid-1990s, a reduction occurred in the virus epidemics, probably due to new approaches which have been applied to rational control of its vector, the whitefly Bemisia tabaci. More recently, TYLCSV has increased again, creating great concern among local tomato producers and stimulating new research. Besides studies on natural enemies of the vector, aiming to investigate their role and distribution, the main current research lines in Sicilia concern the possibility of reducing both whitefly activity, using photoselective plastics as covers, and virus damage, by growing tolerant tomato genotypes. [ABSTRACT FROM AUTHOR]

A virus with filamentous particles was isolated from symptomless plants of Cynara scolymus cvs Romanesco and Terom obtained by in vitro meristem culture in northern Italy. The virus was characterized biologically, physico-chemically and serologically. The cytopathology induced by its infection in two artificial hosts (Chenopodium quinoa and Nicotiana benthamiana) was also investigated. The virus has slightly flexuous elongated particles measuring 12 X 664 nm; its sedimentation coefficient, RNA content, mol. wts. of RNA and coat protein subunits are 150 S, 6%, 2.2 X 10 and 2.9 X 10, respectively. In microprecipitation tests, it resulted serologically related to poplar mosaic virus (popMV) (SDI = 4-5). Cellular inclusions and cytopathology observed in both the artificial hosts conform to those of the carlavirus group. [ABSTRACT FROM AUTHOR]

Discusses the infection of Euphorbia eritrea and Asclepias curassavica by the tomato spotted wilt virus (TSWV) in Liguria, Italy. Detection of the disease by both enzyme-linked immunosorbent assay (ELISA) and immunochromatographic lateral flow assay; Transmission of the virus mechanically to common herbaceous test plant species.

Focuses on the first record of Parietaria mottle virus (PMoV) in Mirabilis jalapa reported in Italy. Confirmation of the spread of the virus into plant species other than Parietaria officinalis; Symptoms reproduced by the infected plants.