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Dwarf Viruses (dwarf + viruse)

Distribution by Scientific Domains
Life Sciences100%

Kinds of Dwarf Viruses

  • yellow dwarf viruse
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    Selected Abstracts

    Barley yellow dwarf viruses (BYDVs) preserved in herbarium specimens illuminate historical disease ecology of invasive and native grasses

    JOURNAL OF ECOLOGY, Issue 6 2007
    CAROLYN M. MALMSTROM
    Summary 1In plant invasion ecology, viruses and other pathogens are often considered in terms of the enemy release hypothesis, which predicts that plants become invasive in new ranges if they escape pathogens from their home range. However, pathogens may sometimes facilitate host spread rather than hinder it. 2Previously, we hypothesized that apparent competition mediated by barley and cereal yellow dwarf viruses (Luteoviridae: BYDVs, CYDVs) may have facilitated historical grassland invasion in California, USA, where Eurasian grasses displaced native grasses in the 18th and 19th centuries (the disease facilitation hypotheses). However, this could have happened only if the viruses were present during the invasion, which is unknown. 3To investigate the historical ecology of BYDVs in California grasses, we analysed preserved virus infections in herbarium specimens and used the historical virus sequences to determine rough time estimates of relevant phylogenetic events. 4The historical viral RNA sequences we identified in invasive and native grasses date from 1917 and are among the oldest recovered from plants thus far and the oldest from North America. 5Herbarium evidence and phylogenetic analysis suggest that BYDVs were likely to have been present in wild grasses during the California grassland invasion and to have shared some functional characteristics with present-day isolates, supporting the disease facilitation hypothesis. 6We found evidence of virus spread from California to Australia (or, less likely, from Australia to California) in the late 19th century, when much horticultural exchange occurred, as well as potential correspondence in the timing of virus diversification events and the beginning of extensive human exchange between the Old and New Worlds. 7Synthesis. Increasing evidence indicates that viruses are important in the ecology of grasslands and may, in some cases, mediate apparent competition among species. Historical data provide essential insight into plant virus ecology and suggest the need to examine human influence on plant virus diversification and spread within natural ecosystems. [source]

    Virus infection and grazing exert counteracting influences on survivorship of native bunchgrass seedlings competing with invasive exotics

    JOURNAL OF ECOLOGY, Issue 2 2006
    C. M. MALMSTROM
    Summary 1,Invasive annual grasses introduced by European settlers have largely displaced native grassland vegetation in California and now form dense stands that constrain the establishment of native perennial bunchgrass seedlings. Bunchgrass seedlings face additional pressures from both livestock grazing and barley and cereal yellow dwarf viruses (B/CYDVs), which infect both young and established grasses throughout the state. 2,Previous work suggested that B/CYDVs could mediate apparent competition between invasive exotic grasses and native bunchgrasses in California. 3,To investigate the potential significance of virus-mediated mortality for early survivorship of bunchgrass seedlings, we compared the separate and combined effects of virus infection, competition and simulated grazing in a field experiment. We infected two species of young bunchgrasses that show different sensitivity to B/CYDV infection, subjected them to competition with three different densities of exotic annuals crossed with two clipping treatments, and monitored their growth and first-year survivorship. 4,Although virus infection alone did not reduce first-year survivorship, it halved the survivorship of bunchgrasses competing with exotics. Within an environment in which competition strongly reduces seedling survivorship (as in natural grasslands), virus infection therefore has the power to cause additional seedling mortality and alter patterns of establishment. 5,Surprisingly, clipping did not reduce bunchgrass survivorship further, but rather doubled it and disproportionately increased survivorship of infected bunchgrasses. 6,Together with previous work, these findings show that B/CYDVs can be potentially powerful elements influencing species interactions in natural grasslands. 7,More generally, our findings demonstrate the potential significance of multitrophic interactions in virus ecology. Although sometimes treated collectively as plant ,predators', viruses and herbivores may exert influences that are distinctly different, even counteracting. [source]

    Virus-Vector Cell Interactions Regulating Transmission Specificity of Soybean Dwarf Luteoviruses

    JOURNAL OF PHYTOPATHOLOGY, Issue 6 2000
    F. E. Gildow
    Abstract Transmission of soybean dwarf viruses (SbDV) indigenous to Japan (SbDV-D) and to the eastern United States (SbDV-Va19) were compared in vector and nonvector aphid species. Absolute vector-specificity was maintained when Aulacorthum solani, Acyrthosiphon pisum, and Myzus persicae were allowed to feed on solutions of either virus (100 ,g/ml) through Parafil© membranes. SbDVD was transmitted only by A. solani, and SbDV-Va19 was transmitted only by A. pisum and M. persicae. Similar results were obtained when individual aphids were micro-injected with 2 ng virus and subsequently allowed to feed on healthy plants. Ultrastructural studies of A. solani and M. persicae indicated that both SbDV-D and SbDV-Va20 were acquired specifically through the aphid hindgut. No difference in hindgut acquisition specificity was observed, and both A. solani and M. persicae were able to transport SbDV-D and SbDV-Va20 into the haemocoel by endocytotic/exocytotic pathways. When injected, SbDV was shown to be associated with only the accessory salivary glands (ASG) in aphids, indicating a high level of tissue specificity. Two different interactions with the ASG were observed for SbDV-D and SbDV-Va20 in A. solani and M. persicae. SbDV-D penetrated the ASG basal lamina of A. solani, but was never observed in the basal lamina of M. persicae. The ASG basal lamina was a barrier to SbDV-D transmission by M. persicae. SbDV-Va19 penetrated the ASG basal lamina of both A. solani and M. persicae. However, SbDV-Va20 was not observed in the ASG cytoplasm in A. solani, indicating that the basal plasmalemma functioned as the transmission barrier. Observations indicated that capsid protein structure, aphid basal lamina composition and cell membrane components influenced virus-aphid interactions regulating SbDV transmission. Zusammenfassung Die Übertragung von Verzwergungsviren der Sojabohne (SbDV), die aus Japan (SbDV-D) bzw. dem Osten der USA (SbDV-Va20) stammten, wurde in Vektor und Nichtvektor-Blattlausarten geprüft. Eine absolute Vektorspezifität wurde stets festgestellt, wenn Aulacorthum solani, Acyrthosiphon pisum und Myzus persicae Lösungen mit einem der Viren (100 ,gml -1) durch Parafilm© Membranen aufnehmen konnten. SbDV-D wurde nur von A. solaniübertragen, SbDV-Va20 nur von A. pisum und M. persicae.Ähnliche Ergebnisse wurden erhalten, wenn einzelne Blattläuse Mikroinjektionen mit 2 ng Virus erhielten und anschließend an gesunden Pflanzen saugen konnten. Feinstrukturelle Untersuchungen von A. solani und M. persicae ergaben, daß SbDV-D und SbDV-Va20 spezifisch durch den Enddarm der Blattläuse aufgenommen wurden. Bei der Aufnahme durch den Enddarm wurde keine unterschiedliche Spezifität festgestellt; A. solani und M. persicae konnten SbDV-D und SbDV-Va20 durch Endo-/Exocytose in die Leibeshöhle aufnehmen. Nach Injektion wurde SbDV bei Blattläusen nur in Assoziation mit den akzessorischen Speicheldrüsen (ASG) beobachtet, was auf eine hohe Gewebsspezifität hindeutet. SbDV-D und SbDV-Va20 zeigten in A. solani und M. persicae zwei unterschiedliche Reaktionen mit den ASG. SbDV-D penetrierte die Basalmembran der ASG von A. solani, wurde in der Basalmembran von M. persicae jedoch in keinem Fall gefunden. Die Basalmembran der ASG fungierte bei M. persicae als Hindernis für eine Übertragung von SbDV-D. SbDV-Va20 penetrierte die Basalmembranen von A. solani und von M. persicae. SbDV-Va20 wurde im ASG-Cytoplasma von A. solani jedoch nicht festgestellt, was darauf hindeutet, daß das Basalplasmalemma als Übertragungshindernis fungierte. Unsere Beobachtungen zeigen, daß die Struktur des Hüllproteins, die Zusammensetzung der Basalmembranen der Blattläuse und die Zellwandbestandteile die Interaktionen zwischen Viren und Blattläusen beeinflussen, welche die SbDV-Übertragung regulieren. [source]

    Long-term changes of aphid vectors of Barley yellow dwarf viruses in north-eastern Italy (Friuli-Venezia Giulia)

    ANNALS OF APPLIED BIOLOGY, Issue 1 2009
    P.G. Coceano
    Abstract Migrations of aphid vectors of Barley yellow dwarf viruses (BYDV) were monitored using a Rothamsted Insect Survey suction trap in Friuli-Venezia Giulia (north-eastern Italy). Catches from 1983 to 2002 were studied for trends, correlations of total catches of each year with those of previous years, correlations between the autumn and the spring + summer catches of the same year and between spring + summer catches of one year with catches of the previous autumn. Infectivity of autumn alates was studied using biological tests, and infectivity indexes were calculated for all vector species and for Rhopalosiphum padi alone. Colonisation of barley and proportion of infected plants were checked in a field close to the suction trap from 1992 to 2002 and related to trap catches. Catches were also correlated to acreage dedicated to cereal and fodder crops in the region. During the 20 years, 15 BYDV vector species were caught in the trap, but only five species were found consistently colonising barley plants during autumn. R. padi was the most numerous species in catches, while Sitobion avenae was the predominant colonising species in the barley field. Relatively to R. padi, S. avenae colonies were about six times more numerous than expected from catches. The yearly abundance of catches of most species did not change significantly during the 20 years, with a few exceptions, significantly correlated to changes in the acreage dedicated to cereal and fodder crops. There was a significant decrease of the autumn catches of both R. padi and the total of BYDV vectors. [source]