Exogenous Application of dsRNA for Protection against Tomato Leaf Curl New Delhi Virus.

Tomato leaf curl New Delhi virus (ToLCNDV) is an emerging plant pathogen, fast spreading in Asian and Mediterranean regions, and is considered the most harmful geminivirus of cucurbits in the Mediterranean. ToLCNDV infects several plant and crop species from a range of families, including Solanaceae, Cucurbitaceae, Fabaceae, Malvaceae and Euphorbiaceae. Up to now, protection from ToLCNDV infection has been achieved mainly by RNAi-mediated transgenic resistance, and non-transgenic fast-developing approaches are an urgent need.

International Trade and Local Effects of Viral and Bacterial Diseases in Ornamental Plants.

Since the 1950s, there have been major changes in the scope, value, and organization of the ornamental plant industry. With fewer individual producers and a strong trend toward consolidation and globalization, increasing quantities of diverse plant genera and species are being shipped internationally. Many more ornamentals are propagated vegetatively instead of by seed, further contributing to disease spread.

[Campaign of labour inspections on the implementation of protection measures against carcinogenic agents in fuel station workers].

Following the reduction in levels of exposure to benzene over the last few decades, the cancer risk of refuelers currently represents an occupational hygiene issue potentially underestimated by employers and workers themselves. Based on the literature data, the occurrence of adverse effects of neoplastic nature can not actually be excluded in this professional category, since it is not possible to define a threshold dose. In the period 2016 - 2019, an extensive focused campaign of labour inspections was conducted in the province of Bari by the OSH inspection services of the Health Local Authority in order to verify the compliance with the legislation on the workers' protection from carcinogenic agents at fuel stations.

The Induction of an Effective dsRNA-Mediated Resistance Against Tomato Spotted Wilt Virus by Exogenous Application of Double-Stranded RNA Largely Depends on the Selection of the Viral RNA Target Region.

Tomato spotted wilt virus (TSWV) is a devastating plant pathogen, causing huge crop losses worldwide. Unfortunately, due to its wide host range and emergence of resistance breaking strains, its management is challenging. Up to now, resistance to TSWV infection based on RNA interference (RNAi) has been achieved only in transgenic plants expressing parts of the viral genome or artificial microRNAs targeting it.

Arbuscular Mycorrhizal Symbiosis Primes Tolerance to Cucumber Mosaic Virus in Tomato.

Tomato plants can establish symbiotic interactions with arbuscular mycorrhizal fungi (AMF) able to promote plant nutrition and prime systemic plant defenses against pathogens attack; the mechanism involved is known as mycorrhiza-induced resistance (MIR). However, studies on the effect of AMF on viral infection, still limited and not conclusive, indicate that AMF colonization may have a detrimental effect on plant defenses against viruses, so that the term "mycorrhiza-induced susceptibility" (MIS) has been proposed for these cases. To expand the case studies to a not yet tested viral family, that is, Bromoviridae, we investigated the effect of the colonization by the AMF on cucumber mosaic virus (CMV) infection in tomato by phenotypic, physiological, biochemical, and transcriptional analyses.

ICTV Virus Taxonomy Profile: .

The family includes viruses with flexuous filamentous virions that are 470-800 nm in length and 12-13 nm in diameter. Alphaflexiviruses have a single-stranded, positive-sense RNA genome of 5.5-9 kb.

Nondestructive Raman Spectroscopy as a Tool for Early Detection and Discrimination of the Infection of Tomato Plants by Two Economically Important Viruses.

Global population forecasts dictate a rapid adoption of multifaceted approaches to fulfill increasing food requirements, ameliorate food dietary value and security using sustainable and economically feasible agricultural processes. Plant pathogens induce up to 25% losses in vegetable crops and their early detection would contribute to limit their spread and economic impact. As an alternative to time-consuming, destructive, and expensive diagnostic procedures, such as immunological assays and nucleic acid-based techniques, Raman spectroscopy (RS) is a nondestructive rapid technique that generates a chemical fingerprinting of a sample, at low operating costs.

Arbuscular Mycorrhizal Symbiosis: Plant Friend or Foe in the Fight Against Viruses?

Plant roots establish interactions with several beneficial soil microorganisms including arbuscular mycorrhizal fungi (AMF). In addition to promoting plant nutrition and growth, AMF colonization can prime systemic plant defense and enhance tolerance to a wide range of environmental stresses and below-ground pathogens. A protective effect of the AMF against above-ground pathogens has also been described in different plant species, but it seems to largely rely on the type of attacker.

Virus-mediated export of chromosomal DNA in plants.

The propensity of viruses to acquire genetic material from relatives and possibly from infected hosts makes them excellent candidates as vectors for horizontal gene transfer. However, virus-mediated acquisition of host genetic material, as deduced from historical events, appears to be rare. Here, we report spontaneous and surprisingly efficient generation of hybrid virus/host DNA molecules in the form of minicircles during infection of Beta vulgaris by Beet curly top Iran virus (BCTIV), a single-stranded DNA virus.

The interaction of Lolium latent virus major coat protein with ankyrin repeat protein NbANKr redirects it to chloroplasts and modulates virus infection.

The Lolium latent virus (LoLV) major coat protein sequence contains a typical chloroplast transit peptide (cTP) domain. In infected Nicotiana benthamiana leaf tissue, LoLV coat proteins can be detected at the chloroplast. In transient expression, several N-terminal deletions of the CP sequence, increasing in length, result in disruption of the domain functionality, markedly affecting intracellular localization.

Deep Sequencing Data and Infectivity Assays Indicate that Chickpea Chlorotic Dwarf Virus is the Etiological Agent of the "Hard Fruit Syndrome" of Watermelon.

(CpCDV), a polyphagous mastrevirus, family , has been recently linked to the onset of the "hard fruit syndrome" of watermelon, first described in Tunisia, that makes fruits unmarketable due to the presence of white hard portions in the flesh, chlorotic mottling on the rind, and an unpleasant taste. To investigate the etiological agent of this disease, total RNA extracted from symptomatic watermelon fruits was subjected to small RNA sequencing through next generation sequencing (NGS) techniques. Data obtained showed the presence of CpCDV and two other viral species.

ICTV Virus Taxonomy Profile: Ophioviridae.

The Ophioviridae is a family of filamentous plant viruses, with single-stranded negative, and possibly ambisense, RNA genomes of 11.3-12.5 kb divided into 3-4 segments, each encapsidated separately.

The coat protein of Alternanthera mosaic virus is the elicitor of a temperature-sensitive systemic necrosis in Nicotiana benthamiana, and interacts with a host boron transporter protein.

Different isolates of Alternanthera mosaic virus (AltMV; Potexvirus), including four infectious clones derived from AltMV-SP, induce distinct systemic symptoms in Nicotiana benthamiana. Virus accumulation was enhanced at 15 °C compared to 25 °C; severe clone AltMV 3-7 induced systemic necrosis (SN) and plant death at 15 °C. No interaction with potexvirus resistance gene Rx was detected, although SN was ablated by silencing of SGT1, as for other cases of potexvirus-induced necrosis.

First Report of Freesia sneak virus Associated with Foliar Necrosis of Freesia refracta in Bulgaria.

In the early spring of 2011 and 2012, severe necrotic leaf symptoms were observed on freesia (Freesia refracta, family Iridaceae) in several greenhouses around Plovdiv (south central Bulgaria). The disease spread and symptom severity in several cultivars (Medeo, Calvados, and Pink Fountain) led to nearly complete production failure for some growers. Initial symptoms consisted of scattered pale, chlorotic, interveinal lesions that coalesced.

From immunity to susceptibility: virus resistance induced in tomato by a silenced transgene is lost as TGS overcomes PTGS.

Tomato line 30.4 was obtained engineering the nucleocapsid (N) gene of tomato spotted wilt virus into plant genome, and immunity to tomato spotted wilt virus infection of its self-pollinated homozygous progeny was observed. Despite the presence of a high amount of transgenic transcripts, transgenic proteins have not been detected, suggesting a mechanism of resistance mediated by RNA.

Lolium latent virus (Alphaflexiviridae) coat proteins: expression and functions in infected plant tissue.

The genome of Lolium latent virus (LoLV; genus Lolavirus, family Alphaflexiviridae) is encapsidated by two carboxy-coterminal coat protein (CP) variants (about 28 and 33 kDa), in equimolar proportions. The CP ORF contains two 5'-proximal AUGs encoding Met 1 and Met 49, respectively promoting translation of the 33 and 28 kDa CP variants. The 33 kDa CP N-terminal domain includes a 42 aa sequence encoding a putative chloroplast transit peptide, leading to protein cleavage and alternative derivation of the approximately 28 kDa CP.

Mutation of a chloroplast-targeting signal in Alternanthera mosaic virus TGB3 impairs cell-to-cell movement and eliminates long-distance virus movement.

Cell-to-cell movement of potexviruses requires coordinated action of the coat protein and triple gene block (TGB) proteins. The structural properties of Alternanthera mosaic virus (AltMV) TGB3 were examined by methods differentiating between signal peptides and transmembrane domains, and its subcellular localization was studied by Agrobacterium-mediated transient expression and confocal microscopy. Unlike potato virus X (PVX) TGB3, AltMV TGB3 was not associated with the endoplasmic reticulum, and accumulated preferentially in mesophyll cells.

Efficiency of VIGS and gene expression in a novel bipartite potexvirus vector delivery system as a function of strength of TGB1 silencing suppression.

We have developed plant virus-based vectors for virus-induced gene silencing (VIGS) and protein expression, based on Alternanthera mosaic virus (AltMV), for infection of a wide range of host plants including Nicotiana benthamiana and Arabidopsis thaliana by either mechanical inoculation of in vitro transcripts or via agroinfiltration. In vivo transcripts produced by co-agroinfiltration of bacteriophage T7 RNA polymerase resulted in T7-driven AltMV infection from a binary vector in the absence of the Cauliflower mosaic virus 35S promoter. An artificial bipartite viral vector delivery system was created by separating the AltMV RNA-dependent RNA polymerase and Triple Gene Block (TGB)123-Coat protein (CP) coding regions into two constructs each bearing the AltMV 5' and 3' non-coding regions, which recombined in planta to generate a full-length AltMV genome.

Pathogenicity of Alternanthera mosaic virus is affected by determinants in RNA-dependent RNA polymerase and by reduced efficacy of silencing suppression in a movement-competent TGB1.

Four biologically active cDNA clones were derived from the Alternanthera mosaic virus (AltMV; genus Potexvirus) isolate, AltMV-SP, which differ in symptoms in infected Nicotiana benthamiana plants. Two clones induced necrosis and plant death; a mixture of all four clones induced milder symptoms than AltMV-SP. Replication of all clones was enhanced by a minimum of fourfold at 15 degrees C.

First Report of Freesia sneak virus in Freesia sp. in Virginia.

In the spring of 2008, freesia, cvs. Honeymoon and Santana, with striking virus-like symptoms similar to freesia leaf necrosis disease were received by the Virginia Tech Plant Disease Clinic from a cut-flower nursery in Gloucester, VA and forwarded for analysis to the USDA-ARS Floral and Nursery Plants Research Unit in Beltsville, MD. Approximately 25% of the plants had coalescing, interveinal, chlorotic, whitish, necrotic or dark brown-to-purple necrotic spots on leaves.