1,721,046 research outputs found
Polymorphisms at the 3’end of the movement protein (MP) gene of grapevine Pinot gris virus (GPGV) affect virus titre and small interfering RNA accumulation in GLMD disease
No full textGrapevine Leaf Mottling and Deformation (GLMD) is a grapevine disease that has been associated with a trichovirus, the grapevine Pinot gris virus (GPGV). A wide diversity in the severity of GLMD disease symptoms has been recorded worldwide, but the relationship of this diversity to the sequence variation in the GPGV genome is still a matter of debate. Results from comparative analysis of GPGV genomic sequences have suggested an association of polymorphisms at the 3’-end of the movement protein (MP) with GLMD severity. Here, the 3’-terminus of the MP gene of a GPGV infectious clone derived from an isolate from grapevine showing severe symptoms (fvg-12), was substituted with a 356 bp synthetic DNA fragment having a sequence resembling that of another GPGV isolate (fvg-15), recovered from an asymptomatic grapevine. The clone containing this chimeric construct was root-inoculated in virus-free Kober rootstocks along with the clones containing the fvg-12 and fvg-15 full length sequence. Remarkable differences in virus titre, accumulation of GPGV-derived small interfering RNAs (siRNAs), alterations in the gene expression of boron transporters and, to a lesser extent, in symptom expression were recorded among plants infected with either one of the three GPGV derived clones. In particular, the chimeric clone behaviour was indistinguishable from that of the donor of the small 356 bp fragment and significantly different from the other. Thus, this work experimentally confirmed the critical role of the GPGV-MP C-terminus in determining the fate of the infection, as it had been previously hypothesized on the basis of comparative sequence analysis
Traditional Approaches and Emerging Biotechnologies in Grapevine Virology
Full text linkEnvironmental changes and global warming may promote the emergence of unknown viruses, whose spread is favored by the trade in plant products. Viruses represent a major threat to viticulture and the wine industry. Their management is challenging and mostly relies on prophylactic measures that are intended to prevent the introduction of viruses into vineyards. Besides the use of virus-free planting material, the employment of agrochemicals is a major strategy to prevent the spread of insect vectors in vineyards. According to the goal of the European Green Deal, a 50% decrease in the use of agrochemicals is expected before 2030. Thus, the development of alternative strategies that allow the sustainable control of viral diseases in vineyards is strongly needed. Here, we present a set of innovative biotechnological tools that have been developed to induce virus resistance in plants. From transgenesis to the still-debated genome editing technologies and RNAi-based strategies, this review discusses numerous illustrative studies that highlight the effectiveness of these promising tools for the management of viral infections in grapevine. Finally, the development of viral vectors from grapevine viruses is described, revealing their positive and unconventional roles, from targets to tools, in emerging biotechnologies
Volatile organic compounds as potential biomarkers of Cadophora luteo-olivacea presence on kiwifruits
No full textCadophora luteo-olivacea is the causal agent of the skin-pitting disease of kiwifruit, a syndrome that appears after 4–5 months of cold storage. However, it is assumed that the infection takes place in the field during fruit development. The present work takes into consideration the production of volatile organic compounds (VOCs) of Actinidia deliciosa ‘Hayward’ at different phenological phases as potential C. luteo-olivacea infection biomarkers. In vitro assays were conducted to gain knowledge on the effect of kiwifruit VOCs on pathogen conidial germination and mycelial growth. VOCs produced by kiwifruit either inoculated or not with C. luteo-olivacea were analysed at different phenological phases by SPME/GC–MS analysis. In particular, ethanol, o-xylene, d-limonene and acetic acid showed a significant increase in the presence of fungal inoculation. Ethanol and d-limonene were also detected as volatile metabolites of the pathogen. The effect of each compound (ethanol, o-xylene, d-limonene and acetic acid) was tested on the fungal conidial germination at different concentrations, showing a growth stimulation at lower amounts. These results show how the production of some VOCs can contribute to the knowledge of fruit–pathogen interaction in the field with the aim of developing future tools for early disease detection and consequent effective control
The conundrum of the connection of grapevine Pinot gris virus with the grapevine leaf mottling and deformation syndrome
No full textSince 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
Interactions between bois noir and the esca disease complex in a Chardonnay vineyard in Italy
Full text linkSpatiotemporal and quantitative monitoring of the fate of “candidatus phytoplasma solani” in tomato plants infected by grafting
Full text linkUnderstanding how phytoplasmas move and multiply within the host plant is fundamental for plant–pathogen interaction studies. In recent years, the tomato has been used as a model plant to study this type of interaction. In the present work, we investigated the distribution and multiplication dynamics of one strain of “Candidatus Phytoplasma (Ca. P.) solani”, (16SrXII-A) in tomato (Solanum lycopersicum L., cv. Micro-Tom) plants. We obtained infected plants by grafting, a fast and effective method to maintain phytoplasma infection. In planta spread and multiplication of “Ca. P. solani” was monitored over time using qualitative and quantitative qPCR. Root, apical shoot, lower leaves, and upper leaves were sampled at each sampling time. We hypothesized that “Ca. P. solani” from the grafting site reached firstly the highest leaf, the apex and the roots; subsequently, the phytoplasmas spread to the rest of the upper leaves and then progressively to the lower leaves. Significant differences were found in “Ca. P. solani” titer among different plant tissues. In particular, the concentration of phytoplasma in the roots was significantly higher than that in the other plant compartments in almost all the sampling dates. Since the roots show rapid colonization and the highest concentration of phytoplasmas, they represent the ideal tissue to sample for an early, sensitive and robust diagnosis
Trigger and suppression of antiviral defenses by grapevine Pinot gris virus (GPGV): novel insights into virus-host interaction.
Full text linkGrapevine Pinot gris virus (GPGV) is an emerging trichovirus that has been putatively associatedwith a novel grapevine disease known as grapevine leaf mottling and deformation (GLMD). Yet the role ofGPGV inGLMD disease is poorly understood, since it has been detected both in symptomatic and symptomless grapevines. Weexploited a recently constructed GPGV infectious clone (pRI::GPGV-vir) to induce an antiviral response in Nicotiana benthamiana plants. In silico prediction of virus-derived small interfering RNAs and gene expression analyses revealed the involvement of DCL4, AGO5, and RDR6 genes during GPGV infection, suggesting the activation of the posttranscriptional gene-silencing (PTGS) pathway as a plant antiviral defense. PTGS suppression assays in transgenic N. benthamiana 16c plants revealed the ability of the GPGV coat protein to suppress RNA silencing. This work provides novel insights on the interaction betweenGPGV and its host, revealing the ability of the virus to trigger and suppress antiviral RNA silencing
The Oxford Nanopore MinION as a Versatile Technology for the Diagnosis and Characterization of Emerging Plant Viruses
No full textThe emergence of novel viral epidemics that could affect major crops represents a serious threat to global food security. The early and accurate identification of the causative viral agent is the most important step for a rapid and effective response to disease outbreaks. Over the last years, the Oxford Nanopore Technologies (ONT) MinION sequencer has been proposed as an effective diagnostic tool for the early detection and identification of emerging viruses in plants, providing many advantages compared with different high-throughput sequencing (HTS) technologies. Here, we provide a step-by-step protocol that we optimized to obtain the virome of "Lamon bean" plants (Phaseolus vulgaris L.), an agricultural product with Protected Geographical Indication (PGI) in North-East of Italy, which is frequently subjected to multiple infections caused by different RNA viruses. The conversion of viral RNA in ds-cDNA enabled the use of Genomic DNA Ligation Sequencing Kit and Native Barcoding DNA Kit, which have been originally developed for DNA sequencing. This allowed the simultaneous diagnosis of both DNA- and RNA-based pathogens, providing a more versatile alternative to the use of direct RNA and/or direct cDNA sequencing kits
Expression of an apple LRR-protein kinase (LRPKm1) after Venturia inaequalis infection in apple leaves tissue
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