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Diversity of three isolates of Zucchini yellow mosaic virus (ZYMV) was analyzed by the biological and genetic characterization. Two isolates were collected from zucchini plants and one from cucumber. The symptoms induced on most hosts were different. In addition, analysis of the coat protein (CP) and nuclear inclusion protein b (Nib) of the ZYMV genome revealed high level of nucleotide variability among the isolates. Comparison of the DNA sequences of 22 isolates from different geographical regions worldwide revealed that the Polish isolates belong to different groups and they do not form a monophyletic cluster with European isolates.
Tomato black ring virus (TBRV) is a serious pathogen of many plants worldwide. TBRV has single stranded RNA genomes divided into two genomic RNAs. In Institute of Plant Protection – National Research Institute we collected different isolates of TBRV from zucchini, cucumber, tomato, potato, Robinia pseudoaccacia L. and Sambucus nigra. Using ELISA test and Dot blot immunoassay we were able to distinguish two serologically related viruses (TBRV and Beet ringspot virus). Results from serological tests were confirmed by RT-PCR. The expected product about 1200 bp was amplified for all isolates tested.
Tomato black ring virus is a quarantine pathogen of many plants worldwide. In Institute of Plant Protection – National Research Institute we collected several TBRV isolates from zucchini, tomato, potato and Robinia pseudoaccacia L. They have single stranded RNA genomes of positive polarity that are divided into two genomic RNAs. Moreover, the presence of defective RNA (D-RNA) associated TBRV was observed. Defective RNAs arise from some viral genomes during prolonged incubation into a host species. In addition, defective interfering RNA (DI-RNA) can modulate virus symptoms, accumulation and replication as well as other important functions therefore influence virus evolution. The serial passage in Chenopodium quinoa of two TBRV isolates TBRV-L1 (obtained from robinia) and TBRV-KC (from zucchini) resulted in arising small RNA in case of TBRV-L1. It was also associated with milder symptoms induced by virus. It indicated the interfering character of small RNA observed. In case of TBRV-KCV after 24 passages no additional bands were observed in gel electrophoresis.
In 2007, a new virus Tomato torrado virus (ToTV) was identified. The occurrence and spread of the virus were reported in many parts of the world. Taking into consideration a low concentration and stability of the virus in plant sap, its poor mechanical transmission as well as effective transmission by whiteflies , the issue that should be solved is the way of virus transmission for very long distances. ToTV belongs to the family Secoviridae including several viruses transmitted by seeds were described, what may be expected also in the case of ToTV. In the preliminary study on the transmission ToTV by seeds a special emphasis was paid to the detection of virus in tomato plants. Antiserum prepared against ToTV was not specific enough for the enzyme-linked immunosorbent assay test (ELISA) but it was useful for immunomolecular techniques for the trapping virus particles (immunocapture – IC) from plant sap. The immunocapture real-time reverse transcription – polymerase chain reaction (IC real-time RT-PCR) techniques were developed for the detection of ToTV in tomato plants grown from seeds.
The diversity of Zucchini yellow mosaic virus (ZYMV) isolates from cucumber and zucchini plants growing in different regions of Poland was analyzed using biological tests and molecular biology techniques. The isolates differed in their host range and symptoms induced by them on a series of plant species. In addition, the analysis of the genetic diversity of the coat protein (CP) gene revealed high level of nucleotide variability among the isolates. Comparison of the CP gene sequences of 70 isolates from different geographical regions worldwide showed that the Polish isolates belong to different groups and they do not form a monophyletic cluster with European isolates. Interestingly, among the central European ZYMV isolates lower variability has been observed previously. The ratio of nonsynonymous to synonymous polymorphic sites showed a dominant negative selection however codons which might undergo positive selection were also identified. Moreover, the evidences for recombination in analyzed sequences of the CP gene of the analyzed ZYMV isolates were provided.
 The complete nucleotide sequence of a Polish isolate of Beet soil-borne virus was determined for the first time. The genome organization was identical with those previously established for isolates from Germany and China. A comparison of the Polish isolate with others deposited in GenBank reveled high level of nucleotide identity, about 98-100%, throughout the genome analyzed. The ratio between non-synonymous and synonymous substitutions was rather low suggesting a negative selective pressure. The non-synonymous mutations were particulary frequent in triple gene block.
Tomato plants are often infected by viral pathogens belonging to different families. As a result of virus‐host interaction numerous mechanisms in plants are induced, such as appearance of additional structures and inclusions in the cytoplasm, or changes in a structure of organelles. For this reason, the analyses of cytological changes within the leaf of tomato, induced by Tomato torrado virus (ToTV) and Pepino mosaic virus (PepMV) were performed. The presence of viral particles in various compartments of individual cell types, arranged specifically for each type of virus was observed. Moreover, in both cases we observed changes in activity of the organelles responsible for the metabolic processes (chloroplasts, mitochondria) and thickened of the cell wall.
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