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Chlorosis Virus (chlorosis + virus)
Kinds of Chlorosis Virus Selected AbstractsStylet penetration behavior resulting in inoculation of a semipersistently transmitted closterovirus by the whitefly Bemisia argentifoliiENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2002D.D. Johnson Abstract The electrical penetration graph (EPG) technique was used to determine what part of stylet penetration behavior by the whitefly vector, Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae), is lettuce chlorosis virus (LCV) inoculated in the host plant Malva parviflora L. LCV is a semipersistently-transmitted closterovirus. Since closteroviruses generally are found in the phloem of their plant hosts, this study tested the hypothesis that virus inoculation occurs during the phloem phase of stylet penetration behavior. Virus-exposed whiteflies were allowed to feed on uninfected host plants, and the whiteflies were divided into two experimental groups: group 1 attained phloem phase on the uninfected plants, and group 2 did not attain phloem phase. Two series of tests were conducted, one where whiteflies were manipulated so that the amount of time spent in non-phloem phase stylet penetration behaviors was similar between group 1 and group 2, and a second series of tests where whiteflies were manipulated so that the number of intracellular punctures made during stylet penetration was similar between group 1 and group 2. Both series of tests indicated that virus inoculation took place primarily during phloem phase. Considering only individual whiteflies shown to be capable of transmitting virus, 11 of 23 whiteflies (48%) in the phloem phase treatment successfully inoculated the virus whereas only one of 19 whiteflies (5%) in the non-phloem phase treatment successfully inoculated the virus (P= 0.00008). [source] Situation of the whiteflies Bemisia tabaci and Trialeurodes vaporariorum in protected tomato crops in Algarve (Portugal),EPPO BULLETIN, Issue 1 2002N. E. Ramos Protected tomato is the most important horticultural crop in the Algarve (south of Portugal). However, the growing area has decreased by almost 48% since 1995, mainly as a result of the pests Bemisia tabaci and Trialeurodes vaporariorum and the epidemics of Tomato yellow leaf curl virus (TYLCV), a Begomovirus transmitted by B. tabaci. Both whiteflies are vectors of economically important viruses. Recently, Tomato chlorosis virus (ToCV), a member of the genus Crinivirus, transmitted by both B. tabaci and T. vaporariorum, was reported infecting tomato crops in Algarve. A study was carried out to evaluate the dynamics of whitefly populations on tomato crops in Algarve. Population counts of B. tabaci were high in the first months of autumn, then decreased until January, when numbers of T. vaporariorum became higher. Counts of B. tabaci then increased again. [source] A generic RT-PCR assay for the detection of LuteoviridaePLANT PATHOLOGY, Issue 3 2010A. Chomi This study, using RT-PCR, is the first comprehensive assessment since 1991 of a generic detection method for the Luteoviridae. Thirteen Luteoviridae species were detected using three separate sets of low-degeneracy generic primers with RT-PCR to amplify 68-, 75- and 129/156-bp regions of the Luteoviridae coat-protein gene. Species detected include all members of the genus Luteovirus [Barley yellow dwarf virus (BYDV) -PAV, BYDV-PAS, BYDV-MAV (129 and/or 156 bp amplicons), Soybean dwarf virus, Bean leafroll virus (68 bp amplicon)] and eight of nine species from the genus Polerovirus [Beet western yellows virus, Beet chlorosis virus, Beet mild yellowing virus, Turnip yellows virus, Potato leafroll virus, Cucurbit aphid-borne yellows virus, Cereal yellow dwarf virus-RPV (68-bp amplicon) and Sugarcane yellow leaf virus (75-bp amplicon)]. These primers were not able to detect Carrot red leaf virus, Sweet potato leaf speckling virus (both belong to unassigned Luteoviridae) and Pea enation mosaic virus-1 (genus Enamovirus). A synthetic positive control containing all primer sequence priming sites was designed to facilitate this method as a generic tool for use with a variety of host plants. The Luteoviridae primers described in this study present a simple infection-detection tool of benefit to biosecurity authorities in nursery-stock surveillance, disease management or outbreak prevention, and may also be useful in detection of as-yet undiscovered species within the Luteovirus and Polerovirus genera. [source] Ultrastructural aspects of tomato leaves infected by Tomato torrado virus (ToTV) and co-infected by other virusesPLANT PATHOLOGY, Issue 2 2010A. Alfaro-Fernández Optical and electron microscopy studies were carried out to investigate the cytopathology induced in tomato leaves infected by Tomato torrado virus (ToTV), a new picorna-like virus associated with the ,Torrado' disease. Infected leaves, showing typical Torrado disease symptoms were surveyed in commercial greenhouses in the main tomato production areas of Spain. The effect of the co-infection of ToTV with other viruses which commonly infect tomato crops was also studied. Ultra-thin sections of ToTV-infected tomato leaves did not show a strong cellular alteration. However, crystalline arrays of isometric virus-like particles (VLPs) of 20,30 nm in the inclusion bodies were observed in phloem parenchyma cells of the infected tissues. Tissues co-infected by ToTV and either Tomato chlorosis virus (ToCV) or Pepino mosaic virus (PepMV) presented more severe cellular alterations. The most deleterious consequences for tomato cells were found in triple infections of ToTV, PepMV and Tomato spotted wilt virus (TSWV), where characteristic cell wall overgrowth was distinguishable, together with a large amount of necrotic cells. [source] Serological and molecular detection of Tomato chlorosis virus and Tomato infectious chlorosis virus in tomatoPLANT PATHOLOGY, Issue 2 2009M. Jacquemond Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV) are two criniviruses inducing similar yellowing symptoms in tomato. An approximately 4 kb central region of the genomic RNA2 of French ToCV and TICV isolates was sequenced. TICV, for which no other sequences were available, appeared as a distant species in the genus, being close only to LIYV (Lettuce infectious yellows virus) for some, but not all, proteins. ToCV has more than 98% nucleotide identity with isolates from the US and Spain, and sequencing the CP gene of several isolates collected in different regions in southern France during 2 years suggested a unique origin. Polyclonal antisera were produced using capsid proteins of both viruses expressed in Escherichia coli. DAS-ELISA assays were developed for routine diagnosis and conditions for preparing samples for an optimized detection were determined. No cross-reactions were observed. However, some false-negative results, corresponding to samples giving ELISA readings close to the detection limit were regularly detected, particularly for ToCV (approximately 5% of the samples). A triplex RT-PCR assay was thus developed, which allowed detection of both viruses in a one-step protocol. An internal PCR control was included, which in addition showed that it could be used as a control for the entire RT-PCR procedure. Finally, combining DAS-ELISA in a first round, and triplex RT-PCR for doubtful samples, appeared the best way to achieve a reliable diagnosis of these viruses. [source] Comparative whitefly transmission of Tomato chlorosis virus and Tomato infectious chlorosis virus from single or mixed infectionsPLANT PATHOLOGY, Issue 2 2009A. Dalmon Tomato chlorosis virus (ToCV) and Tomato infectious chlorosis virus (TICV) are two criniviruses that are emerging worldwide, and induce similar yellowing diseases in tomato crops. While TICV is transmitted only by Trialeurodes vaporariorum, ToCV is transmitted by three whitefly species in two genera Trialeurodes vaporariorum, T. abutilonea and Bemisia tabaci. The efficiency of transmission by T. vaporariorum from plants infected by one virus or by both was compared, and the probability of virus transmission by a single whitefly was derived from group testing experiments. The estimated transmission probabilities ranged from 0ˇ01 to 0ˇ13, and were not significantly different between ToCV and TICV, or between single and mixed infections. Experiments using B. tabaci as a vector and source plants infected by TICV and ToCV did not reveal any functional trans-complementation for transmission of TICV by ToCV, suggesting that if this phenomenon occurs in nature, it is at a very low frequency. Possible reasons why TICV did not establish in southern France while ToCV is now endemic are discussed. [source] Distribution and properties of geographically distinct isolates of sugar beet yellowing virusesPLANT PATHOLOGY, Issue 2 2005M. Stevens From a total of 261 yellow sugarbeet leaves collected from 10 countries representing three continents, the incidence and distribution of strains of Beet mild yellowing virus (BMYV), Beet chlorosis virus (BChV) and Beet yellows virus (BYV) were analysed using serological and molecular methods. BMYV was found in all countries except Greece, and more frequently in the northern and western areas of Europe, whereas BYV predominated in Turkey, Spain, Greece, the USA and Chile. BChV, originally found in the USA and the UK in 1989, was identified in France, Spain, the Netherlands and Chile. Nine sugar beet poleroviruses, plus a reference isolate of Turnip yellows virus (TuYV, syn. Beet western yellows virus), were further characterized and compared. Isolates obtained from sugar beet infected this species, but not oilseed rape or lettuce; all isolates except one infected Capsella bursa-pastoris. The coat-protein sequences of these isolates were highly similar, with the consensus sequence representing 89% of nucleotide residues. Within the coat-protein gene, two regions were identified that could represent specific epitopes to which monoclonal antibody BYDV-PAV-IL-1 could bind; this antibody is used to distinguish beet poleroviruses in ELISA. Comparison of the sequences at the 5, end showed that sequence homology existed only between isolates with the same host range. The first sequence data of polerovirus isolates from Chile are presented, showing that the coat protein and the 5, end of their genomes are highly similar to those of BMYV isolates found in Europe. Chilean polerovirus isolates may have been imported from the northern hemisphere in sugar beet breeding material. [source] Epidemics of Tomato torrado virus, Pepino mosaic virus and Tomato chlorosis virus in tomato crops: do mixed infections contribute to torrado disease epidemiology?ANNALS OF APPLIED BIOLOGY, Issue 3 2010P. Gómez Torrado disease was first observed in protected tomato crops in the Murcia province of Spain in spring 2001, causing serious concern to regional tomato producers. The disease-causing agent was initially identified as a picorna-like bipartite plant RNA virus, now known as Tomato torrado virus (ToTV), but several additional torradoviruses inducing similar disease symptoms have been described more recently. We studied the incidence of torradoviruses between 2005 and 2008 in two parts of Murcia (Spain) where tomato crops are grown commercially. We also analysed the potential association among ToTV, Pepino mosaic virus (PepMV) and Tomato chlorosis virus (ToCV) in samples showing torrado symptoms of varying severity. ToTV was the only torradovirus found in the samples (predominantly as single infections), but double and triple infections comprising ToTV, PepMV and/or ToCV were also detected. There was no evidence of a specific association among the viruses as the frequencies of mixed infections did not deviate from those expected to occur by chance. Statistical analysis of the potential association between torrado symptoms and the type of infection (single or multiple) was inconclusive. To determine whether co-infections with ToTV and PepMV have any marked influence on the torrado disease, we analysed torrado symptom severity and virus accumulation in tomato plants experimentally infected with ToTV-CE, PepMV-Sp13 and PepMV-PS5 in single and mixed infections. The severity of the torrado symptoms was not affected by the presence of PepMV. In single infections, the ToTV titre remained very low, reaching its maximum in the early stages of infection and declining rapidly thereafter, whereas the disease symptoms became more severe over the same timescale. In mixed infections, the accumulation of both ToTV and PepMV was altered with respect to single infections, and the magnitude of this alteration appeared to be virus and strain specific. Therefore, ToTV and PepMV mixed infections may modulate the epidemiology of both viruses in a complex way by altering virus fitness. The impact of our studies on efforts to track and prevent the spread of torrado disease is discussed. [source] The effects of Beet mild yellowing virus and Beet chlorosis virus on the yield of UK field-grown sugar beet in 1997,1999 and 2000ANNALS OF APPLIED BIOLOGY, Issue 1 2004MARK STEVENS Summary The separate effects of the aphid-transmitted poleroviruses; Beet mild yellowing virus (BMYV) and Beet chlorosis virus (BChV), on the yield of field-grown sugar beet were studied following different inoculation dates from May to July in 1997,1999 and 2000. Each sugar beet plant within the appropriate plots was infected with virus using at least 10 wingless viruliferous Myzus persicae per plant. In all 3 years, overall yield losses caused by BMYV were negatively correlated with time of infection with early season (May) inoculations causing 18,27% losses in sugar yield but late season losses only 4,15%. BChV decreased the sugar yield and sugar content of beet following early season inoculations, although the effects on sugar yield were more variable (range 8,24%) and the virus appeared to be less damaging compared to BMYV. However, inoculations with BChV in July of each year caused greater root and sugar losses than inoculations with BMYV at that time. Both poleroviruses increased the sodium content of the roots early in the season, although neither virus had an effect on potassium levels at any stage. [source] | ||||||||||