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Open AccessArticle

The Mechanism of Resistance of EUROPEAN Plum to Plum pox virus Mediated by Hypersensitive Response Is Linked to VIRAL NIa and Its Protease Activity

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Bernardo Rodamilans

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Johannes Hadersdorfer

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Plants 2023, 12(8), 1609; https://doi.org/10.3390/plants12081609 - 10 Apr 2023

Viewed by 361

Abstract

Plum pox virus (PPV) infects Prunus trees across the globe, causing the serious Sharka disease. Breeding programs in the past 20 years have been successful, generating plum varieties hypersensitive to PPV that show resistance in the field. Recently, a single tree displaying typical [...] Read more.

Plum pox virus (PPV) infects Prunus trees across the globe, causing the serious Sharka disease. Breeding programs in the past 20 years have been successful, generating plum varieties hypersensitive to PPV that show resistance in the field. Recently, a single tree displaying typical PPV symptoms was detected in an orchard of resistant plums. The tree was eradicated, and infected material was propagated under controlled conditions to study the new PPV isolate. Performing overlapping PCR analysis, the viral sequence was reconstructed, cloned and tested for infectivity in different ‘Jojo’-based resistant plums. The results confirmed that the isolate, named PPV-D ‘Herrenberg’ (PPVD-H), was able to infect all these varieties. Analyses of chimeras between PPVD-H and a PPV-D standard isolate (PPVD) revealed that the NIa region of PPD-H, carrying three amino acid changes, was enough to break the resistance of these plums. Experiments with single and double mutants showed that all changes were essential to preserve the escaping phenotype. Additionally, one of the changes at the VPg-NIapro junction suggested the involvement of controlled endopeptidase cleavage in the viral response. Transient expression experiments in Nicotiana benthamiana confirmed that NIa cleavage in PPVD-H was reduced, compared to PPVD, linking the observed behavior to an NIa cleavage modulation. Full article

(This article belongs to the Special Issue Advances in Plant Viral Diseases)

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Open AccessArticle

Comparative Analysis of Bioactive Compounds in Two Globe Artichoke Ecotypes Sanitized and Non-Sanitized from Viral Infections

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Maria Concetta de Pinto

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Tiziana Mascia

Plants 2023, 12(8), 1600; https://doi.org/10.3390/plants12081600 - 10 Apr 2023

Viewed by 535

Abstract

Globe artichoke ecotypes sanitized from plant pathogen infections are characterized by high vegetative vigor, productivity, and quality of capitula. The recent availability on the market of these plants has renewed the interest of farmers and pharmaceutical industries in the crop. Globe artichoke exhibits [...] Read more.

Globe artichoke ecotypes sanitized from plant pathogen infections are characterized by high vegetative vigor, productivity, and quality of capitula. The recent availability on the market of these plants has renewed the interest of farmers and pharmaceutical industries in the crop. Globe artichoke exhibits interesting nutraceutical properties due to the high content of health-promoting bioactive compounds (BACs), such as polyphenols, that could be extracted from waste biomass. The production of BACs depends on several factors including the plant portion considered, the globe artichoke variety/ecotype, and the physiological status of the plants, linked to biotic and abiotic stresses. We investigated the influence of viral infections on polyphenol accumulation in two Apulian late-flowering ecotypes “Locale di Mola tardivo” and “Troianella”, comparing sanitized virus-free material (S) vs. naturally virus-infected (non-sanitized, NS) plants. Transcriptome analysis of the two ecotypes highlighted that differentially expressed genes (DEGs), in the two tested conditions, were mainly involved in primary metabolism and processing of genetic/environmental information. The up-regulation of the genes related to the biosynthesis of secondary metabolites and the analysis of peroxidase activity suggested that their modulation is influenced by the phytosanitary status of the plant and is ecotype-dependent. Conversely, the phytochemical analysis showed a remarkable decrease in polyphenols and lignin accumulation in S artichokes compared to NS plants. This unique study analyzes the potential of growing vigorous, sanitized plants, in order to have high amounts of ‘soft and clean’ biomass, finalized for BAC extraction for nutraceutical purposes. This, in turn, opens new perspectives for a circular economy of sanitized artichokes, in line with the current phytosanitary standards and sustainable development goals. Full article

(This article belongs to the Special Issue Advances in Plant Viral Diseases)

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Open AccessArticle

A Novel and Highly Inclusive Quantitative Real-Time RT-PCR Method for the Broad and Efficient Detection of Grapevine Leafroll-Associated Virus 1

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Félix Morán

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Antonio Olmos

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Miroslav Glasa

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Marilia Bueno Da Silva

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Varvara Maliogka

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Thierry Wetzel

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Ana Belén Ruiz-García

Plants 2023, 12(4), 876; https://doi.org/10.3390/plants12040876 - 15 Feb 2023

Viewed by 856

Abstract

Grapevine (Vitis vinifera L.) is one of the most important crops in the world due to its economic and social impact. Like many other crops, grapevine is susceptible to different types of diseases caused by pathogenic microorganisms. Grapevine leafroll-associated virus 1 (GLRaV-1) [...] Read more.

Grapevine (Vitis vinifera L.) is one of the most important crops in the world due to its economic and social impact. Like many other crops, grapevine is susceptible to different types of diseases caused by pathogenic microorganisms. Grapevine leafroll-associated virus 1 (GLRaV-1) is a virus associated with grapevine leafroll disease and it is considered at the national and European level as a pathogen that must be absent in propagative plant material. For this reason, the availability of specific, sensitive and reliable detection techniques to ascertain the sanitary status of the plants is of great importance. The objective of this research was the development of a new GLRaV-1 detection method based on a TaqMan quantitative real-time RT-PCR targeted to the coat protein genomic region and including a host internal control in a duplex reaction. To this end, three new GLRaV-1 full genomes were recovered by HTS and aligned with all sequences available in the databases. The method has been validated following EPPO standards and applied for the diagnosis of field plant material and transmission vectors. The new protocol designed has turned out to be highly sensitive as well as much more specific than the current available methods for the detection and absolute quantitation of GLRaV-1 viral titer. Full article

(This article belongs to the Special Issue Advances in Plant Viral Diseases)

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Open AccessArticle

Grafting to Manage Infections of the Emerging Tomato Leaf Curl New Delhi Virus in Cucurbits

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Mariarosaria Mastrochirico

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Roberta Spanò

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Tiziana Mascia

Plants 2023, 12(1), 37; https://doi.org/10.3390/plants12010037 - 21 Dec 2022

Viewed by 886

Abstract

Tomato leaf curl New Delhi virus (ToLCNDV) is an emerging begomovirus (Geminiviridae family) listed in the EPPO Alert List 2, present in the Mediterranean area and in Italy, where it was reported in 2015 in Sicilian courgette. The virus is widespread in [...] Read more.

Tomato leaf curl New Delhi virus (ToLCNDV) is an emerging begomovirus (Geminiviridae family) listed in the EPPO Alert List 2, present in the Mediterranean area and in Italy, where it was reported in 2015 in Sicilian courgette. The virus is widespread in cucurbits where it causes up to 100% production losses. In 2018, ToLCNDV was isolated in Apulia (southern Italy) in commercial fields of zucchini squash and since then its recurrent outbreaks generated justified concern among growers. Thus, a sustainable and environmentally friendly approach must be adopted. Genetic resistances have been identified in Cucurbita moschata and Luffa cylindrica but, compared to genetic resistance, grafting could provide a faster and more flexible solution because the graft wounding induces tolerance rather than resistance against airborne virus infection. Compared to tolerance, the up-regulation of resistance genes requires energy resources mobilized at the expense of primary metabolism, plant growth, and development. Results of screening among twenty-one local cucurbit cvs. ecotypes and accessions to evaluate tolerance levels against rub-inoculation of ToLCNDV led to the identification of potential rootstocks to attain suitable levels of tolerance against the virus in commercial cucurbit varieties. Cucurbit plants were challenged by a ToLCNDV isolated in Apulia denoted ToLCNDV-Le and evaluated for disease symptoms development and viral DNA accumulation up to 28 days after inoculation. On the basis of disease symptoms developed, plants were classified as tolerant, moderately tolerant, moderately susceptible, and susceptible. Cucumis melo cv. Barattiere did not show any detectable disease symptoms and very low levels of viral DNA accumulation was recorded; thus, it was used as rootstock for some of the remaining cucurbit genotypes that were used as scions. The tolerance trait was transmitted to the otherwise susceptible and moderately susceptible cucurbit genotypes grafted onto the cv. Barattiere. The results of this study suggest practical implications of the approach described. Full article

(This article belongs to the Special Issue Advances in Plant Viral Diseases)

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Open AccessArticle

Adaptation of a Potyvirus Chimera Increases Its Virulence in a Compatible Host through Changes in HCPro

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Plants 2022, 11(17), 2262; https://doi.org/10.3390/plants11172262 - 30 Aug 2022

Viewed by 1052

Abstract

A viral chimera in which the P1-HCPro bi-cistron of a plum pox virus construct (PPV-GFP) was replaced by that of potato virus Y (PVY) spread slowly systemically in Nicotiana benthamiana plants and accumulated to levels that were 5−10% those of parental PPV-GFP. We [...] Read more.

A viral chimera in which the P1-HCPro bi-cistron of a plum pox virus construct (PPV-GFP) was replaced by that of potato virus Y (PVY) spread slowly systemically in Nicotiana benthamiana plants and accumulated to levels that were 5−10% those of parental PPV-GFP. We tested whether consecutive mechanical passages could increase its virulence, and found that after several passages, chimera titers rose and symptoms increased. We sequenced over half the genome of passaged chimera lineages infecting two plants. The regions sequenced were 5′NCR-P1-HCPro-P3; Vpg/NIa; GFP-CP, because of being potential sites for mutations/deletions leading to adaptation. We found few substitutions, all non-synonymous: two in one chimera (nt 2053 HCPro, and 5733 Vpg/NIa), and three in the other (2359 HCPro, 5729 Vpg/NIa, 9466 CP). HCPro substitutions 2053 AUU(Ile)→ACU(Thr), and 2359 CUG(Leu)→CGG(Arg) occurred at positions where single nucleotide polymorphisms were observed in NGS libraries of sRNA reads from agroinfiltrated plants (generation 1). Remarkably, position 2053 was the only one in the sequenced protein-encoding genome in which polymorphisms were common to the four libraries, suggesting that selective pressure existed to alter that specific nucleotide, previous to any passage. Mutations 5729 and 5733 in the Vpg by contrast did not correlate with polymorphisms in generation 1 libraries. Reverse genetics showed that substitution 2053 alone increased several-fold viral local accumulation, speed of systemic spread, and systemic titers. Full article

(This article belongs to the Special Issue Advances in Plant Viral Diseases)

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Open AccessArticle

Enhanced Apiaceous Potyvirus Phylogeny, Novel Viruses, and New Country and Host Records from Sequencing Apiaceae Samples

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Plants 2022, 11(15), 1951; https://doi.org/10.3390/plants11151951 - 27 Jul 2022

Cited by 2 | Viewed by 1364

Abstract

The family Apiaceae comprises approximately 3700 species of herbaceous plants, including important crops, aromatic herbs and field weeds. Here we report a study of 10 preserved historical or recent virus samples of apiaceous plants collected in the United Kingdom (UK) import interceptions from [...] Read more.

The family Apiaceae comprises approximately 3700 species of herbaceous plants, including important crops, aromatic herbs and field weeds. Here we report a study of 10 preserved historical or recent virus samples of apiaceous plants collected in the United Kingdom (UK) import interceptions from the Mediterranean region (Egypt, Israel and Cyprus) or during surveys of Australian apiaceous crops. Seven complete new genomic sequences and one partial sequence, of the apiaceous potyviruses apium virus Y (ApVY), carrot thin leaf virus (CaTLV), carrot virus Y (CarVY) and celery mosaic virus (CeMV) were obtained. When these 7 and 16 earlier complete non-recombinant apiaceous potyvirus sequences were subjected to phylogenetic analyses, they split into 2 separate lineages: 1 containing ApVY, CeMV, CarVY and panax virus Y and the other CaTLV, ashitabi mosaic virus and konjac virus Y. Preliminary dating analysis suggested the CarVY population first diverged from CeMV and ApVY in the 17th century and CeMV from ApVY in the 18th century. They also showed the “time to most recent common ancestor” of the sampled populations to be more recent: 1997 CE, 1983 CE and 1958 CE for CarVY, CeMV and ApVY, respectively. In addition, we found a new family record for beet western yellows virus in coriander from Cyprus; a new country record for carrot torradovirus-1 and a tentative novel member of genus Ophiovirus as a co-infection in a carrot sample from Australia; and a novel member of the genus Umbravirus recovered from a sample of herb parsley from Israel. Full article

(This article belongs to the Special Issue Advances in Plant Viral Diseases)

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Open AccessEditor’s ChoiceArticle

High-Throughput Sequencing Discloses the Cucumber Mosaic Virus (CMV) Diversity in Slovakia and Reveals New Hosts of CMV from the Papaveraceae Family

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Ana Belén Ruiz-García

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Miroslav Glasa

Plants 2022, 11(13), 1665; https://doi.org/10.3390/plants11131665 - 23 Jun 2022

Cited by 3 | Viewed by 1529

Abstract

Cucumber mosaic virus (CMV; Cucumovirus, Bromoviridae) is an omnipresent virus characterized by a large host range and high genetic variability. Using high-throughput sequencing, we have characterized near complete genomes of 14 Slovak CMV variants from different plant hosts. Of these, three variants [...] Read more.

Cucumber mosaic virus (CMV; Cucumovirus, Bromoviridae) is an omnipresent virus characterized by a large host range and high genetic variability. Using high-throughput sequencing, we have characterized near complete genomes of 14 Slovak CMV variants from different plant hosts. Of these, three variants originated from the Papaveraceae species (oilseed poppy, common poppy and great celandine), previously poorly described as CMV natural hosts. Based on a BLAST search and phylogenetic analysis, the Slovak CMV isolates can be divided into two genetically different Groups, Ia and II, respectively. The SL50V variant, characterized by a divergent RNA2 sequence, potentially represents a reassortant variant. In four samples (T101, SL50V, CP2, MVU2-21), the presence of satellite CMV RNA was identified along with CMV. Although mechanically transmitted to experimental cucumber plants, the role of satellite RNA in the symptomatology observed could not be established due to a complex infection of original hosts with different viruses. Full article

(This article belongs to the Special Issue Advances in Plant Viral Diseases)

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Open AccessArticle

The Virome of ‘Lamon Bean’: Application of MinION Sequencing to Investigate the Virus Population Associated with Symptomatic Beans in the Lamon Area, Italy

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Plants 2022, 11(6), 779; https://doi.org/10.3390/plants11060779 - 15 Mar 2022

Cited by 2 | Viewed by 1981

Abstract

‘Lamon bean’ is a protected geographical indication (PGI) for a product of four varieties of bean (Phaseolus vulgaris L.) grown in a specific area of production, which is located in the Belluno district, Veneto region (N.E. of Italy). In the last decade, [...] Read more.

‘Lamon bean’ is a protected geographical indication (PGI) for a product of four varieties of bean (Phaseolus vulgaris L.) grown in a specific area of production, which is located in the Belluno district, Veneto region (N.E. of Italy). In the last decade, the ‘Lamon bean’ has been threatened by severe virus epidemics that have compromised its profitability. In this work, the full virome of seven bean samples showing different foliar symptoms was obtained by MinION sequencing. Evidence that emerged from sequencing was validated through RT-PCR and ELISA in a large number of plants, including different ecotypes of Lamon bean and wild herbaceous hosts that may represent a virus reservoir in the field. Results revealed the presence of bean common mosaic virus (BCMV), cucumber mosaic virus (CMV), peanut stunt virus (PSV), and bean yellow mosaic virus (BYMV), which often occurred as mixed infections. Moreover, both CMV and PSV were reported in association with strain-specific satellite RNAs (satRNAs). In conclusion, this work sheds light on the cause of the severe diseases affecting the ‘Lamon bean’ by exploitation of MinION sequencing. Full article

(This article belongs to the Special Issue Advances in Plant Viral Diseases)

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Open AccessBrief Report

First Identification of Fig Virus A and Fig Virus B in Ficus carica in Italy

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Serafina Serena Amoia

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Michela Chiumenti

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Angelantonio Minafra

Plants 2023, 12(7), 1503; https://doi.org/10.3390/plants12071503 - 29 Mar 2023

Viewed by 476

Abstract

Extracts of double-stranded RNA from three fig cultivars from an Apulian (Southern Italy) germplasm collection were used for high-throughput sequencing and revealed the presence of two distinct, recently described closteroviruses. Sequences obtained from these Apulian isolates belong to fig virus A and fig [...] Read more.

Extracts of double-stranded RNA from three fig cultivars from an Apulian (Southern Italy) germplasm collection were used for high-throughput sequencing and revealed the presence of two distinct, recently described closteroviruses. Sequences obtained from these Apulian isolates belong to fig virus A and fig virus B and cover 38 and 25% of their RNA genome, respectively. Primer sets designed on selected contigs confirmed the presence of each virus in infected plants. A close phylogenetic relationship, investigated in a fragment of HSP70h protein, occurs among these isolates and the reference genomes. A nucleotide divergence (ranging from 10 to 30% along the different genes) was observed among our isolates and the reference genomes. This is the first finding of these virus species in autochthonous fig accessions in Europe. Full article

(This article belongs to the Special Issue Advances in Plant Viral Diseases)

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