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Two wheat-infecting isolates of WDV-WDV-B and WDV-F- were collected in the field of Martonvásár and Nagykovácsi. The complete genomes were amplified by PCR, cloned into pBKS+ plasmid and sequenced. The nucleotide divergence in the total genome of the five isolates-WDV- Fra, WDV-Cz, WDV-Swe, WDV-B and WDV-F-originating from different part of Europe were found to be 0.44-1.69%. The four genes- MP, CP, RepA and Rep-and two non-coding region-LIR and SIR- were compared and a phylogenetic tree was constructed.

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Last year pepper growers observed symptoms referring to virus-infection in pepper plantations in plastic tunnels. Infected plants showed mosaic symptoms or mottling of the leaves, while on the fruits necrotic spots developed. These symptoms referred to a tobamovirus infection. Collected samples were examined by serological and pathological methods, followed by the biological characterisation of the isolates. For serological studies the DAS-ELISA method was used, in which the pathogen was identified as pepper mild mottle tobamovirus. During the pathological examination different host-plants have been used including some pepper varieties containing different L genes (L + –L 4). It was found, that the Hungarian isolates belonged to the P 1,2 pathotype and were closely related to the Spanish isolate (PMMV-S). PCR- studies proved the presence of the PMMoV P 1,2 pathotype in Hungary as well.

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Maize dwarf mosaic is the most widespread virus disease affecting corn production in Hungary and Bulgaria. Samples from virus infected maize were collected from different part of Bulgaria and employed test plants, ELISA serological method and RT-PCR in order to identify the viral pathogen. Maize dwarf mosaic virus (MDMV) was detected in all tested samples. For further investigation three MDMV isolates were selected and cloned. Cloned cDNAs representing the coat protein gene of the virus have been sequenced. The coat protein genes of Bulgarian and Hungarian isolates of MDMV were compared. The nucleotide sequence identity and amino acid sequence similarity of the coat protein region varied from 88% to 99.1% and from 95.1% to 99.6%, respectively. The N-terminal region of coat protein was compared with other members SCMV subgroup and phylogenetic tree was constructed.

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The prevalence of gastric Helicobacter infection in finishing pigs and the influence of this infection on gastric lesions was studied. Stomachs of 89 finishing pigs from 27 randomly selected herds were sampled at the slaughterhouse. Forty cases (Group A) were selected based upon the presence of gross pathological lesions in the pars oesophagea, and further 49 cases were obtained at random (Group B). Three samples of gastric tissue (junction of pars oesophagea and pars cardiaca, fundic area, and pyloric area) were collected from each stomach for histological and immunohistochemical examination. Helicobacter antigen was detected in 76 cases (85.4%). No association was found between the presence of Helicobacter in the stomach and the occurrence of gross pathological lesions in the pars oesophagea or gastritis detected on histological examination. However, a significant association was found between the occurrence of Helicobacter in the pyloric area and the presence of erosions/ulcers in the pars oesophagea (OR: 7.01, p = 0.022) in Group B. A significant association was also evident between the presence of Helicobacter and glandular lesions (dilatation of the glands + glandular abscess + degeneration of glandular epithelial cells). In conclusion, Helicobacter infection seems to be a contributing factor to pathological changes in the stomach of finishing pigs.

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Zucchini yellow mosaic potyvirus (ZYMV)was isolated in Hungary from cucumber for the first time in 1995 and now it is widespread causing devastating epidemics in cucurbit crops. Four isolates were chosen from different cucurbit plants collected in 1995 and 1999 and mole- cular variability of N-terminal region of coat protein was studied.Hungarian isolates show lower molecular variability within themselves than with ZYMV isolates from other geographical origins.Hungarian isolates have amino acid sequences specific only to them that suggest common ancestor.

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Nucleotide and amino acid sequences of the helper component protease (HC-Pro) and the coat protein (CP) of two Hungarian Potato virus Y (PVY) isolates, differing in aphid transmissibility were determined. Isolate PVY-5 belongs to the common “O” strain (PVY O ), whereas isolates PVY-98 and PVY-111 belong to the “N” (PVY N ) and the PVY-NTN and PVY-H to the “NTN” (PVY NTN ) strains, respectively. The PVY-5 isolate varied significantly from the others in aphid transmission and in the ability to systemically infect potato plants. To elucidate whether these differences were due to mutations affecting known functional motifs, the corresponding cistrons of the two proteins were sequenced and aligned. Our analysis showed that none of the well-known motifs, responsible for aphid transmission in the two proteins had been affected. However, the defective isolate had two natural mutations in the HC-Pro in the vicinity of the PTK motif, and a number of mutations in the CP, distributed both in the N-terminus and the central region. As these two proteins are the only known viral participants in the aphid transmission mechanism, it is likely that some of the observed mutations might be involved in this process. Thus, our results indicate that other, previously unidentified sequences or factors may influence virus-vector interactions and transmission of PVY.

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Barley-infecting isolates of Wheat dwarf virus (WDV) were collected in the field in the vicinity of the cities Dunakiliti, Heves and Siófok, in Hungary. Viral genomic DNA was amplified by the rolling circle amplification technique, digested with Hind III, cloned into pBSK+ plasmid and sequenced. The clones were of the same size and showed above 99% identity to each other. Based on DNA sequences WDV-D01, WDV-H1 and WDV-H07 isolates showed high identity (94–99%) to isolates of WDV barley strain and Barley dwarf virus and lower identity to Oat dwarf virus (71% identity) and WDV wheat strains (85% identity).

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Erwinia amylovora (Burrill, Winslow et al.) is one of the most important pathogens of pear and apple and subject to strict quarantine regulations worldwide. Fire blight disease causes serious damages in pear orchards in Hungary. The aim of our experiment was to test the susceptibility of pear cultivars to Hungarian E. amylovora isolates under laboratory conditions. For inoculation test isolates were chosen from different host plants, areas and years. Seven traditional pear cultivars were chosen for testing. Fruit infection was rated according to the diameter of spots produced by the pathogen around the inoculation puncture. Cultivars and isolates were assigned to five susceptibility groups (symptomless, low susceptibility, moderate susceptibility, susceptible and very susceptible). The Hungarian Erwinia amylovora isolates showed different results. We found different susceptibility of traditional pear cultivars. The cultivars Alexander Lucas and Stössel tábornok represented the less susceptible category. Eldorado, Serres Olivér, Diel vajkörte were moderately susceptible. Thus, the most susceptible cultivars were Téli esperes and Drouard elnök. In conclusion, these results can be used for the classification of Erwinia amylovora isolates and in future breeding programmes for resistance.

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In May 2011, young Impatiens walleriana Hook. f. plants showing downy mildew symptoms were collected from a greenhouse (Kecskemét, Hungary). The upper surface of affected leaves turned yellow and white fungal-like growth was observed on the underside. Diseased plants wilted and rapidly collapsed, resulting in losses of nearly 100%. Downy mildew of impatiens can be caused by two pathogens, Plasmopara obducens or Plasmopara constantinescui (syn: Bremiella sphaerosperma), which can be distinguished by the symptoms and by morphology of sporangiophores and sporangia. For molecular identification the 5′-end of the large subunit of ribosomal RNA gene was amplified by PCR using NL1 and NL4 primers and cloned and sequenced. The nucleotide sequence of the Hungarian isolate showed highest identity (99.72%) with two isolates of Plasmopara obducens from the United Kingdom and Serbia. On the basis of the symptoms, molecular and morphological characters, the pathogen was identified as P. obducens. The appearance of the pathogen in Hungary seriously endangers the production of I. walleriana, which is a popular ornamental in gardens and city parks. The chemical plant protection is not effective against the pathogen, by the occurrence of the first symptoms the diseased plants should be removed from the plantlet and must be destroyed.

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A destructive seed-borne pathogen, formerly described as Pleospora papaveracea affects opium poppy (Papaver somniferum L.) plants, grown in Hungary, causing considerable qualitative and quantitative losses. The symptoms of the disease were frequently observed in the field between 1999 and 2006. Seventeen Hungarian isolates were obtained from poppy and cultures were established on malt extract agar from naturally infected seeds, diseased foliage, pods and stem. The pathogens proved to be Crivellia papaveracea and a distinct taxon, Brachycladium papaveris based on morphological characterization of conidia, conidiophores and cultures, moreover molecular investigation of the ITS region. Significant morphological differences were observed among the isolates originating from distinct plant parts, however, cultural characteristics were similar. Molecular studies revealed that morphological and cultural differences or similarities do not correspond with taxonomic position of the isolates. Morphological variation of the isolates mainly depended on their origin and might be explained with the differences of microclimatic conditions.

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