Transmission of plant viruses by fungi

Adams, Michael J.

doi:10.1111/j.1744-7348.1991.tb05649.x

Cited by 78 publications

(37 citation statements)

References 45 publications

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“…bornovanus, and Olpidium transmission of several other small spherical plant viruses, have shown that the transmission process is highly specific (1,6). For example, O. bornovanus transmits CNV but not Tobacco necrosis necrovirus (TNV), and conversely, O. brassicae transmits TNV but not CNV (10,34).…”

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confidence: 99%

Identification of Specific Cucumber Necrosis Virus Coat Protein Amino Acids Affecting Fungus Transmission and Zoospore Attachment

Kakani

Sgro

Rochon

2001

J Virol

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Cucumber necrosis virus (CNV) is naturally transmitted in the soil by zoospores of the fungal vectorOlpidium bornovanus. Successful transmission requires that virus particles attach to the surface of zoospores prior to zoospore encystment on host roots. Mechanically passaged CNV was screened for mutants deficient in fungus transmission. We found six such mutants, exhibiting transmission efficiencies ranging from approximately 14 to 76% of that of wild-type (WT) CNV. Results of in vitro virus-zoospore binding assays show that each mutant binds to zoospores less efficiently than WT CNV (21 to 68%), suggesting that defects in transmission for these mutants are at least partially due to inefficient zoospore binding. Analysis of the structure of the CNV coat protein subunit and trimer indicates that affected amino acids in all of the mutants are located in the shell or protruding domain and that five of six of them are potentially exposed on the surface of the virus particle. In addition, several of the mutated sites, along with a previously identified site in a Efficient transmission of the majority of plant viruses requires distinct invertebrate or fungal vectors. In most cases, transmission has been shown to be a highly specific process in which only certain vectors can transmit certain viruses (for reviews, see references 4, 6, 13, 14, 23, and 35). These observations suggest that virus particles as well as vectors contain specific sites that mediate their recognition. The coat protein (CP) of a plant virus has been shown to play an important role in transmission, and particular amino acids within the CP have been shown to be essential for this process (for reviews, see references 4, 6, 13, 14, 23, and 35). However, for the most part, the exact role of these amino acids in transmission including their potential role in vector attachment, is not known. Recent work with cucumber necrosis virus (CNV) has suggested that attachment of virions to vector zoospores is an important aspect of the transmission process (24).CNV, a member of the genus Tombusvirus, is a 30-nm spherical virus with a monopartite positive-sense RNA genome (25). Transmission of CNV in nature occurs via zoospores of the Chytridiomycete fungus, Olpidium bornovanus (6, 9, 24). Zoospores and virus particles are released independently into the soil from the roots of infected plants. Virus is adsorbed onto the plasma membrane of zoospores and then enters into roots upon zoospore encystment. Studies of CNV transmission by O.bornovanus, and Olpidium transmission of several other small spherical plant viruses, have shown that the transmission process is highly specific (1, 6). For example, O. bornovanus transmits CNV but not Tobacco necrosis necrovirus (TNV), and conversely, O. brassicae transmits TNV but not CNV (10, 34). Moreover, different isolates of O. bornovanus transmit different viruses with varying efficiency (7), and different strains of TNV are transmitted with varying efficiency by the same O. brassicae isolate (17,33,34). Electron microscopy st...

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Identification of Specific Cucumber Necrosis Virus Coat Protein Amino Acids Affecting Fungus Transmission and Zoospore Attachment

Kakani

Sgro

Rochon

2001

J Virol

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“…Bound virus then enters the cells of plants following the encystment of zoospores on roots (1,4). Several studies have shown that the transmission process is highly specific (1,4). For example, O. brassicae transmits the necrovirus Tobacco necrosis virus (TNV-A) but not the tombusvirus Cucumber necrosis virus (CNV), and conversely, O. bornovanus transmits CNV but not TNV-A (7,30).…”

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“…It has been proposed that transmission occurs following the release of zoospores and virus from different plants into the soil and subsequent adsorption of virus particles onto the surfaces of zoospores. Bound virus then enters the cells of plants following the encystment of zoospores on roots (1,4). Several studies have shown that the transmission process is highly specific (1,4).…”

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Evidence that Binding of Cucumber Necrosis Virus to Vector Zoospores Involves Recognition of Oligosaccharides

Kakani

Robbins

Rochon

2003

J Virol

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“…O SBWMV apresenta genoma de RNA bipartido encapsulado em partículas alongadas retilíneas, de fita simples e senso positivo (Shirako, 1998). A transmissão do vírus ocorre pela colonização dos pêlos radiculares de plantas através dos zoosporos virulíferos de P. graminis, considerado um parasita obrigatório de raízes de gramíneas (Barr, 1979) que pode persistir por longos períodos em raízes em decomposição ou no solo (Adams, 1991). Os sintomas da virose variam de mosaico verde a mosaico amarelo, ocorrendo mais freqüentemente em plantas com desenvolvimento em áreas mais baixas, especialmente durante extensos períodos de frio e alta umidade do solo (Larsen et al, 1985).…”

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Incidência e índice de doença do mosaico do trigo em cereais de inverno e em gramíneas de verão, associados ao Polymyxa graminis

2002

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Incidence and disease index of Soil-borne wheat mosaic virus on winter cereals and summer grasses associated with the fungus Polymyxa graminisThe Soil-borne wheat mosaic virus (SBWMV) is transmitted by the fungus Polymyxa graminis. To evaluate the incidence and the disease index (DI%) and the presence of the vector in the root system, an experiment was carried out using: oat (Avena strigosa and A. sativa), barley (Hordeum vulgare), triticale (Triticum secale), wheat (Triticum aestivum), Lilium multiforum, mayze (Zea mays), sorghum (Sorghum bicolor), Pannisetum americanum, Digitaria sp. and Brachiaria sp. The experiment was conducted during two sowing periods. Incidence was calculated based on the percentage of the symptomatic plants and grades (0-5) were given INTRODUÇÃOO trigo (Triticum aestivum L.) é um dos cultivos mais afetados por doenças causadas por fungos, bactérias e vírus (Mehta, 1978). Entre as doenças de importância para a cultura, está a virose causada pelo vírus do mosaico do trigo (Soilborne wheat mosaic vírus, SBWMV) gênero Furovirus (Campbell, 1996), que tem como vetor o fungo Polymyxa graminis Ledingham (Campbell, 1996). O SBWMV apresenta genoma de RNA bipartido encapsulado em partículas alongadas retilíneas, de fita simples e senso positivo (Shirako, 1998). A transmissão do vírus ocorre pela colonização dos pêlos radiculares de plantas através dos zoosporos virulíferos de P. graminis, considerado um parasita obrigatório de raízes de gramíneas (Barr, 1979) que pode persistir por longos períodos em raízes em decomposição ou no solo (Adams, 1991). Os sintomas da virose variam de mosaico verde a mosaico amarelo, ocorrendo mais freqüentemente em plantas com desenvolvimento em áreas mais baixas, especialmente durante extensos períodos de frio e alta umidade do solo (Larsen et al., 1985).Os fatores que influenciam a transmissão do vírus são microscópio luminoso, atribuindo-se níveis de infestação pela quantidade de grupos de esporos de resistência de P. graminis. Em espécies de aveia, não foram observados sintomas e esporos de resistência do vetor. Na cultura da cevada, não foram observados sintomas, mas sim esporos de resistência no sistema radicular. Para o triticale e o trigo, na primeira época de plantio, a incidência e ID (%) foram mais elevados quando comparados à segunda época. Observou-se uma relação direta entre o ID (%) e a quantidade de esporos de resistência. Nas gramíneas de verão, não foram observados sintomas de SBWMV nem esporos de resistência no sistema radicular. Palavras-chave adicionais: SBWMV, Furovirus, esporos de resistência, virose.to determine the DI (%). Root segments were collected, then stained with solution of cotton blue-lactofenol and visualized in optical microscope. The quantity of resting spores groups was rated. No symptoms were observed on oat species, however, the presence of resting spores in moderate quantities was observed on barley. The incidence and DI (%) for the triticale and wheat in the first sowing period were higher than in the second one. A di...

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Transmission of plant viruses by fungi

Cited by 78 publications

References 45 publications

Identification of Specific Cucumber Necrosis Virus Coat Protein Amino Acids Affecting Fungus Transmission and Zoospore Attachment

Identification of Specific Cucumber Necrosis Virus Coat Protein Amino Acids Affecting Fungus Transmission and Zoospore Attachment

Evidence that Binding of Cucumber Necrosis Virus to Vector Zoospores Involves Recognition of Oligosaccharides

Incidência e índice de doença do mosaico do trigo em cereais de inverno e em gramíneas de verão, associados ao Polymyxa graminis

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