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Viral cross-protection in plants is a phenomenon, where a mild virus isolate can protect plants against damage caused by a severe challenge isolate of the same virus. It has been used on a large scale in cases where no resistant plants are available. We examined differences in cross-protection between pathotypes of Pepino mosaic virus representing Chilean 2 genotype. The potential of a mild PepMV-P22 isolate to protect tomato against more aggressive challenge isolates causing yellowing and necrotic symptoms was established. The challenge isolates were PepMV-P5-IY (yellowing), PepMV-P19 (necrotic) and PepMV-P22 K67E (artificial necrotic mutant of PepMV-P22 which differ from PepMV-P22 only by a point mutation). Efficient cross-protection was obtained using mild PepMV-P22 against PepMV-P5-IY. After a challenge inoculation with PepMV-P19 or PepMV-P22 K67E symptoms severity were significantly reduced in comparison to non-protected plants; however, necrotic symptoms appeared two months after coinfection. The real-time PCR analysis revealed that the level of accumulation of the necrotic isolate in tomato plants was even 5–7 times higher than that of PepMV-P22.
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.
The aim of the presented studies was to determine a casual agent of zucchini soft rot under the field conditions in the region of Kujawy. In 2009 and 2010, after heavy rain and high temperatures, a mass occurrence of soft rot on the zucchini stems was recorded, leading to a significant reduction in the yield. From zucchini diseased tissue with the soft rot symptoms, some cultures of bacteria were isolated. The isolates giving a positive reaction in pathogenicity test were marked as C1, C2 and C3. Phenotypic characterization of the C1 and C3 isolates allowed to classify them into Erwinia genus and the isolate C2 into Corynebacterium. The further identification using BIOLOG system and sequencing 16S rDNA partial genes, allowed finally to identicate the isolates C1 and C3 as Pectobacterium carotovorum ssp. carotovorum and isolate C2 as Corynebacterium. Studied isolates caused strong soft rot on cucumber and zucchini slices in less than 24 hours after inoculation. The same isolates were reisolated from rotting tissue what confirmed their identity with those ones used for inoculation.
In 2013 and 2014 in the Plant Disease Clinic of Institute of Plant Protection – National Research Institute in Poznań, chrysanthemum plants showing symptoms of stunted growth, mosaic and malformation of leaves and abnormal pigmentation of flowers were tested. All plants were analyzed using biological, electron microscopy and molecular biology methods. The plants were examined for the presence of the following pathogens: Chrysanthemum virus B (CVB), Tomato aspermy virus (TAV), Chrysanthemum stunt viroid (CSVd) and Chrysanthemum chlorotic mottle viroid (CChMVd). The presence of CVB was confirmed in the samples collected from 15 plants. The isolates were genetically identical and shared high level of similarity with isolates from India and Japan.
Globalization resulted in increased international movement of both people and plant material or plant products, including seeds. It is estimated that up to one third of all plant viruses might be seed-borne in at least one of their hosts. In this way viruses may be comparatively easy spread to regions where they have not previously been reported. Dissemination of viruses by seeds might be minimized by using the molecular diagnostic tools. In this paper a problems connected with the detection of viruses in seeds are presented.
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.
Wirus żółtej mozaiki cukinii (Zucchini yellow mosaic virus, ZYMV) oraz mozaiki arbuza (Watermelon mosaic virus, WMV) są bardzo powszechne i należą obecnie do najgroźniejszych patogenów wirusowych roślin dyniowatych, powodujących duże straty ekonomiczne w uprawach cukinii. W latach 2003-2008 zebrano kilka izolatów ZYMV, różniących się między sobą zarówno biologicznie, jak i genetycznie. Porównywane przez nas izolaty porażały różny zakres roślin wskaźnikowych. Dodatkowo, przeprowadzając charakterystykę dwóch regionów genomu: białka płaszcza oraz białka Nib wykazano, że polskie izolaty należą do różnych grup filogenetycznych i nie tworzą jednej grupy z izolatami europejskimi. W roku 2008, w 15 roślinach cukinii z objawami mozaiki na liściach stwierdzono obecność WMV. Sekwencja nukleotydów polskiego izolatu WMV, w porównaniu z sekwencjami dostępnymi w Banku Genów, wykazała 98% podobieństwa z sekwencjami izolatów z Chin i z Korei i tylko 93% z izolatami z Francji i Pakistanu.
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.
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