Spread of Citrus tristeza virus in an area of Sicily.

Molecular analysis suggests that recent Citrus tristeza virus outbreaks in Italy were originated by at least two independent introductions

Citrus tristeza virus (CTV) is the causal agent of the most important virus disease of citrus. Numerous CTV isolates differing in biological and molecular characteristics have been reported worldwide. Recently, CTV was detected in Italy in several citrus crops from three separate areas: (1) Cassibile, province of Syracuse; (2) Massafra, province of Taranto; and (3) Belpasso, province of Catania. CTV isolates from Massafra and Cassibile were mild, whereas isolates from Belpasso induced severe symptoms. To study the genetic variation of CTV populations of these areas, 150 samples per area were examined by single strand conformation polymorphism (SSCP) and nucleotide sequence analysis of CTV g…

Genetic variation and evolutionary analysis ofPepino mosaic virusin Sicily: insights into the dispersion and epidemiology

Pepino mosaic virus (PepMV) is a highly infectious potexvirus that causes a severe disease in tomato (Solanum lycopersicum) crops worldwide. In Sicily, the first outbreak was detected in a single greenhouse in 2005 and it was promptly eradicated. However, in 2008, a large number of greenhouses were simultaneously affected, and it was impossible to eradicate or control the virus. This study addressed the dispersion and the genetic diversity of PepMV isolates obtained from the outbreak in Sicily, in comparison with worldwide PepMV isolates, to gain insight into the factors determining the evolution and epidemiology of the virus. A total of 1800 samples from plants with and without symptoms we…

La tristeza degli agrumi..

Begomoviruses Infecting Tomato Crops in Panama

The key regions in Panama involved in open field- and greenhouse-grown commercial tomato production, including the Chiriquí, Veraguas, Herrera, Los Santos, Coclé and Panama Oeste provinces, were surveyed for the incidence and distribution of begomoviruses in the growing seasons of 2011 and 2012. The surveys took place in 14 of the 51 districts of the above-mentioned provinces and comprised all relevant tomato production areas of the provinces. A total of 28 tomato plots were surveyed. The exact location of each plot was geo-referenced using a hand-held Global Positioning System unit. In total, 319 individual tomato plants (181 in 2011 and 138 in 2012) were sampled. Plants displayed diverse …

First report of Tomato leaf curl New Delhi virus affecting zucchini squash in an important horticultural area of southern Italy

Tomato leaf curl New Delhi virus (ToLCNDV) is a bipartite begomovirus (family Geminiviridae) which infects species in the families Cucurbitaceae and Solanaceae (Padidam et al., 1995; Mizutani et al., 2011). Begomoviruses are transmitted by the whitefly Bemisia tabaci in a persistent manner (Rosen et al., 2015). In October 2015, severe symptoms not previously reported by growers in the horticultural area of the Province of Trapani (Sicily, Italy) were observed on zucchini squash (Cucurbita pepo) in open fields. The symptoms included yellow mosaic, severe leaf curling, swelling of veins of young leaves, shortening of internodes, roughness of the skin of fruit and reduced fruit size; the sympt…

Variability Among Italian Citrus tristeza virus Isolates Revealed by SSCP Analysis, Cloning and Sequencing

Malattie da virus, viroidi e fitoplasmi degli agrumi in Italia e metodi di diagnosi

First report of Tomato leaf curl Sinaloa virus infecting tomato crops in Panama

In April 2011 and September 2012, virus-like symptoms were observed in open field- and greenhouse-grown tomato crops (Solanum lycopersicum) in Chiriquí, the westernmost province of Panama. Samples from symptom-bearing plants (127 in all) were collected and tested for the presence of begomoviruses by polymerase chain reaction (PCR) assays with sets of degenerated primers designed to amplify parts of the DNA-A and DNA-B components (Rojas et al., 1993; Table 1). Products of the expected sizes, obtained with both DNA-A- and DNA-B-specific primers for 49 samples, suggested infection with New World bipartite begomoviruses. This corresponds to an incidence of 26% (8 plants) in open field, and 43% …

Population genetics of cucumber mosaic virus infecting medicinal, aromatic and ornamental plants from northern Italy

An epidemiological survey carried at the Herb Garden of Casola Valsenio (Emilia Romagna region; Northern Italy) from 2006 to 2009 resulted in finding Cucumber mosaic virus (CMV) as the infectious agent of several ornamental, medicinal and aromatic plants. All CMV-infected plant species showed leaf symptoms followed, in some cases, by flower colour-breaking and stunting. Genetic analysis consisted in the characterization of movement protein gene of each CMV-isolate by single strand polymorphism analysis and sequencing. Phylogenetic trees identified only two isolates as member of subgroup II, while all other isolates were part of subgroup IA. This survey confirms an unexpected increment of CM…

Characterization of p20 and p23 genes in Corsican isolates of Citrus tristeza virus.

Tristeza disease, caused by the Citrus tristeza virus (CTV), is the most important viral disease for almost all the citrus species. Main syndromes are quick decline, stem pitting, vein clearing and seedlings yellows but expression and intensity of symptomatology depends on the interactions of the factors involved in the pathosystem such as host-strain-rootstock-climate-vector. Several isolates of CTV have been studied all over the world. Two Corsican isolates have been previously characterized, the K strain from Marumi kumquat, known to be symptomless on Mexican lime, and the CaL -1 from calamondin inducing stem pitting, but no sequences of p20 gene are published or available in GenBank. Tw…

First report of Southern tomato virus in tomato crops in Italy

Twenty-five tomato plants (Solanum lycopersicum) showing symptoms of viral disease were sampled from different greenhouses in the Ragusa province (Southern Italy) in summer 2015. Plants showed chlorosis on leaves and fruits and deformation and depressed spots of dark colour which later evolved into necrosis (Fig. 1). These symptoms were observed on the entire cluster of fruit making the product unsaleable. Based on these symptoms, samples were analysed for Cucumber mosaic virus, Pepino mosaic virus (PepMV), Potato virus Y (PVY), Tomato mosaic virus and Tomato spotted wilt virus by DAS-ELISA with polyclonal antibodies (Loewe Phytodiagnostica, Germany), and for the emerging Southern tomato vi…

Diffusione del virus della “Tristeza” degli agrumi (CTV) in Sicilia.

High genetic stability of potato yellow mosaic Panama virus infecting tomato in Panama

The relevant regions in Panama involved in commercial tomato production, including the Chiriqui, Veraguas, Herrera, Los Santos and Panama Oeste provinces, were surveyed for the distribution and genetic diversity of potato yellow mosaic Panama virus (PYMPV) in the growing seasons of 2011 and 2012. A total of 28 tomato plots were surveyed and 314 individual tomato plants were sampled. DNA was extracted from each plant for a subsequent rolling circle amplification (RCA) analysis, to confirm the presence of begomovirus infections. The samples displaying a positive RCA reaction were subsequently analysed by PCR with a specific primer pair to identify PYMPV. This virus was detected in samples col…

Gravi malformazioni in melanzana in Sicilia associate alla presenza di fitoplasmi

Stunting and leaf malformation were repeatedly observed during vegetative growth in eggplant cultivations located in Sicily (Ragusa). Symptoms appear during first weeks after transplantation, and modify normal shape of plants as well as decrease their production, in several cases stunting was present but only in half of the plant. The disease was scattered distributed in the fields and with percentages below 10%. Samples were collected from symptomatic and asymptomatic plants, and shoots and midribs were used for nucleic acid exstraction to verify possible phytoplasma presence and identity. Nested PCR assays with primers P1/P7 followed by R16mF1/R16mR1 (Gundersen and Lee, 1996) allow to obt…

Basil (Ocimum basilicum), a new host of Pepino mosaic virus.

Pepino mosaic virus (PepMV), a member of the genus Potexvirus , was first described in 1980 on pepino ( Solanum muricatum ) and was later isolated from different wild species of the genus Solanum (formerly Lycopersicon ) (Soler et al ., 2002). PepMV has been reported in several European countries and in North America, causing disease in tomato. In July 2008, plants of basil ( Ocimum basilicum ) showing interveinal chlorosis on young leaves were observed in three greenhouses in Sicily, in the area where tomato plants were found to be infected by PepMV in 2005 (Davino et al ., 2006). The disease was transmitted mechanically to Nicotiana benthamiana , producing chlorotic spots and leaf deforma…

Recombination profiles between Tomato yellow leaf curl virus and Tomato yellow leaf curl Sardinia virus in laboratory and field conditions: evolutionary and taxonomic implications

Tomato yellow leaf curl Sardinia virus and Tomato yellow leaf curl virus have co-existed in Italian tomato crops since 2002 and have reached equilibrium, with plants hosting molecules of both species plus their recombinants being the most frequent case. Recombination events are studied in field samples, as well as in experimental co-infections, when recombinants were detected as early as 45 days following inoculation. In both conditions, recombination breakpoints were essentially absent in regions corresponding to ORFs V2, CP and C4, whereas density was highest in the 3′-terminal portion of ORF C3, next to the region where the two transcription units co-terminate. The vast majority of brea…

Genetic variation and evolutionary analysis of Cucumber mosaic virus in medicinal, aromatic and ornamental plants from Northern Italy

The genetic variation and evolution of Cucumber mosaic virus (CMV) (1) infecting aromatic, medicinal and ornamental plants in Northern Italy were studied by sequence analysis of the movement protein gene and comparison with equivalent sequences of isolates from other countries. Comparison of nonsynonymous and synonymous substitutions at each codon suggested that 30% of amino acid sites were under negative selection and only one was under positive selection. Phylogenetic inference, nucleotide diversity estimation, neutrality tests and genetic differentiation analysis revealed a high nucleotide diversity of CMV in Northern Italy with respect to areas of other countries [1,2] and suggested tha…

First Report of Tomato torrado virus Infecting Tomato in Italy.

In 2009 and 2010, approximately 2% of plants had disease symptoms, including initial leaflet chlorosis that later developed into necrotic spots and general necroses along the leaflet. Fruit production on affected plants was substantially reduced and necroses were also present. Total RNA was extracted from five symptomatic plant samples using the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and analyzed by reverse transcription (RT)-PCR with specific primer pair: TR2F (5′ GAAGGACGAAGAGCGACTG 3′), and TR2R (5′ AAGGTAGGTATGCGTTTGC 3′) (1). The primers amplified a 575-bp fragment within the coat protein Vp23 of Tomato torrado virus (ToTV). No RT-PCR products were observed when water or asym…

Survey on virus disease affecting Poligala myrtifolia in Liguria.

First outbreak of Pepper vein yellows virus infecting sweet pepper in Italy

Sweet pepper (Capsicum annum) is an economically important crop worldwide, including Sicily where about 4,000 hectares are grown each year. In October 2015, severe symptoms not previously reported by growers in the horticultural area of the province of Trapani (Sicily, Italy) were observed on sweet pepper plants in eight different greenhouses. Symptoms included upward leaf curling, internodal shortening and interveinal yellowing. Symptoms were more evident in the upper part of the plants. These symptoms were reminiscent of those caused by poleroviruses. In the greenhouse, symptoms were evident in about 35% of the plants. Three samples per greenhouse (24 in total) were collected for analysis.

Tristeza degli agrumi e portinnesti.

Pepino mosaic virus and Tomato chlorosis virus causing mixed infection in protected tomato crops in Sicily.

Tomato Yellow Leaf Curl: one disease, many viruses.

Simultaneous detection of the seven main tomato-infecting RNA viruses by two multiplex reverse transcription polymerase chain reactions

Cucumber mosaic virus, Tomato spotted wilt virus, Tomato mosaic virus, Tomato chlorosis virus, Pepino mosaic virus, Torrado tomato virus and Tomato infectious chlorosis virus cause serious damage and significant economic losses in tomato crops worldwide. The early detection of these pathogens is essential for preventing the viruses from spreading and improving their control. In this study, a procedure based on two multiplex RT-PCRs was developed for the sensitive and reliable detection of these seven viruses. Serial dilutions of positive controls were analysed by this methodology, and the results were compared with those obtained by ELISA and singleplex versions of RT-PCR. The multiplex and…

Emergence and Phylodynamics of Citrus tristeza virus in Sicily, Italy

Citrus tristeza virus (CTV) outbreaks were detected in Sicily island, Italy for the first time in 2002. To gain insight into the evolutionary forces driving the emergence and phylogeography of these CTV populations, we determined and analyzed the nucleotide sequences of the p20 gene from 108 CTV isolates collected from 2002 to 2009. Bayesian phylogenetic analysis revealed that mild and severe CTV isolates belonging to five different clades (lineages) were introduced in Sicily in 2002. Phylogeographic analysis showed that four lineages co-circulated in the main citrus growing area located in Eastern Sicily. However, only one lineage (composed of mild isolates) spread to distant areas of Sici…

Citrus tristeza virus: ten years of investigation in Sicily

Cucumber mosaic viurus infecting Thevetia nereifolia and Nandina domestica.