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Trees of prune (Prunus domestica L.), cv. Jojo, were inoculated by chip budding with three different strains of PPV isolated from European plum in the Czech Republic. These isolates included Plum pox virus M strain (PPV-M), Plum pox virus D strain (PPV-D) and a PPV-recombinant both strains (PPV-Rec). The results of the evaluation of the inoculated trees over 2 years are presented. Trees of plum cv. Jojo behaven differently to infection with the three PPV strains. A strong hypersensitive reaction appeared a year after inoculation with PPV-M and PPV-Rec strains, although not all inoculated tree died. PPV must have been present in the tissue of cv. Jojo because the virus was transferred to the rootstock St. Julien. Plants of the rootstock became systemically infected with the PPV-M and PPV-Rec strains, showing severe PPV symptoms. The presence of PPV was proved by ELISA in leaves of rootstock St. Julien, but not in leaves of cv. Jojo. Inoculation with strain PPV-D resulted in partial hypersensitive reaction of plants of cv. Jojo, but after initial stunting and partial death of shoots recovering of plants was observed.

Cherry leaf roll virus (CLRV), Myrobalan latent ringspot virus (MLRSV) and Strawberry latent ringspot virus (SLRSV) were transferred by budding to woody trees, hybrid Ishtara, peach cv. GF 305 and cv. Lesiberian. Three buffers with antioxidants and stabilisers: 0.01M phosphate with 1% caffeine; 0.007M phosphate-0.01M veronal with 0.01M cysteine hydrochloride and 0.007 EDTA; 0.015M phosphate with 1% nicotine and 0.066M phosphate buffer without additives were compared for their efficiency in mechanical transmission from woody sources to herbaceous hosts (Chenopodium quinoa and C. amaranticolor). 0.007M phosphate-0.01M veronal buffer with 0.01M cysteine hydrochloride, and 0.007 EDTA and 0.015M phosphate buffer with 1% nicotine were found to be the best buffers for the three nepoviruses. Both biological transmission to herbaceous assay hosts and detection by ELISA in the investigated tree are necessary to reliably detect the three nepoviruses. Biological detection is reliable from April to June, and in September and October. ELISA detection is also more difficult in July and August. The suitability of C. quinoa and C. amaranticolor to maintain CLRV, MLRSV and SLRSV was compared. C. amaranticolor plants were found to be more suitable for CLRV and SLRSV, infected plants grow over 6 months after mechanical inoculation by the nepoviruses. C. quinoa plants proved to be most suitable for maintenance of MLRSV, while C. amaranticolor is a symptomless host of MLRSV. Reinoculation with the nepoviruses is recommended in intervals of 4 to 6 months.

So far, the identification of the nematode species Xiphinema vuittenezi relied mainly on time-consuming morphological and morphometrical studies. Therefore, a polymerase chain reaction (PCR) protocol was optimised that both reliably and rapidly identifies X. vuittenezi. The internal transcribed spacer (ITS) species-specific primer of ribosomal DNA gene of X. vuittenezi was used. Nine populations of this species from Central Bohemia were investigated by means of PCR.

The suitability of different apple tissues for Apple stem grooving virus (ASGV) detection throughout the year was checked by RT-PCR and ELISA. Detectable amounts of ASGV were generally found in all tissues (bark, dormant buds, petals and leaves) tested by RT-PCR from January to mid-June. Leaves during flowering (in May) were the most suitable tissues for the virus detection by both methods (RT-PCR and ELISA). The leaves collected in summer (June, July and August) or other tissues such as bark, dormant buds and petals were not reliable for ASGV detection by ELISA.

Twenty-eight American peach cultivars were screened for their reaction to Plum pox virus (PPV). The cultivars were evaluated for the presence and intensity of PPV symptoms in leaves and fruits, and the relative concentration of PPV protein in flowers was determined by ELISA. The results allowed to divide the cultivars into four groups: cultivars Flame Prince, Cotender, Newhaven, Ruby Prince, Sun Prince, Jefferson, Camden and Jersey Queen were characterised as medium resistant to PPV; cultivars Loring, Blaze Prince, June Prince and Legend were classified as tolerant; cultivars Quachita Gold, O'Henry, Crest Haven, Biscos, Sentry, Fire Prince, Carogem, Carolina Belle, Redglobe and Harvester were rated as medium susceptible; and cultivars Bounty, Summer Prince, Gold Prince, Redhaven, Gala and Sunbrite were characterised as highly susceptible to PPV.

The incidence of Zucchini yellow mosaic virus (ZYMV) was monitored in the south Moravian region of the Czech Republic during 1997-2001. Crops of gherkin, squash, zucchini and cucumbers were found infected with ZYMV, manifested by symptoms of severe stunting and yellowing with deformed leaves and fruits. Twenty to eighty percent of infected plants were recorded. Six isolates of ZYMV from four localities were differentiated on indicator plants; three of them were maintained as being typical for differences in pathogenicity. Overwintered weed species were tested for the presence of the virus. ZYMV was detected by ELISA in one plant of Tripleurospermum maritimum out of 46 tested, and in two plants of Stellaria media out of 29 tested in 2001. Such tests were repeated in 2002, and ZYMV was detected in three plants of T. maritimum out of 45 tested, in three plants of S. media out of 52, and in two plants of Trifolium repens out of 17 tested. The virus was successfully transmitted from T. maritimum, S. media and T. repens to indicator plants of Cucurbita pepo convar. giromontiina. Back-transmission of ZYMV was proved by ELISA, electron microscopy and symptoms. T. maritimum was found to be a new natural host of ZYMV.

Plum pox virus (PPV) is widely distributed in plums and myrobalans in western, central and easternBohemia, in north-western, central and north-easternMoravia of theCzechRepublic. In southernBohemia and partly also in southernMoravia there is only a low and sporadic incidence. Naturally growing plums and myrobalans, and plums growing along roads were found to be the main sources and reservoirs of PPV infection. This high incidence in naturally growing plum and myrobalan trees makes it impossible to grow plum cultivars that are susceptible to PPV; only resistant cultivars can be grown in this country. In blackthorns the occurrence of PPV is limited to the regions with high and long-term presence of the virus. Therefore, we can conclude that blackthorn is not the primary, but a secondary source of PPV. On the other hand, sweet and sour cherries at localities of central and westernBohemia, and of southernMoravia are PPV-free. Till now the presence of strain PPV-C was not proved in theCzechRepublic. Strain PPV-M was proved only in two plum and one damson trees. It was also found in one apricot and one peach orchard planted with imported nursery material. Strain PPV-M appears to have been introduced recently and is absent from or has a very low incidence in spontaneous PPV hosts, while the widespread and long-term dissemination of strain PPV-D may indicate that it originated in the Czech Republic.

From 1997 to 2000 the distribution of Apple stem grooving virus (ASGV) in selected intensive apple orchards was investigated at six sites in the Czech Republic. Detection of ASGV was by ELISA. The virus was found to be commonly distributed; it was detected in over 50 % of the tested trees. Some cultivars were infected up to 100 %, while several were found to be virus-free. A high incidence of infected trees appeared in both older (20 years) and younger (7 to 8 years) orchards. This emphasizes the necessity to initiate the certification of the health condition of nursery material according to the system recommended by the EPPO.

In 1999, split vegetation tops in onions, cv. Stutgartska, grown in the surroundings of Prague, Bohemia, were observed. Such plants developed two or more bulbs from one originally planted. In addition, irregular and asymmetrical drying of the apical parts of outer skirts and in some cases scaling of the outer parts of divided bulbs occurred. Such divided bul bs suffered su bstantially higher damage during storage in winter; premature budding and grow the of individual parts was frequent. Further splitting of the vegetation tops into two to five parts and followed by premature budding was observed in individual parts of divided bulbs. Ultrathin sections were prepared from roots and leaves of divided bulbs. Phytoplasma bodies were found in tissues of both roots and leaves. Such bodies were not found in roots and leaves of healthy looking and undivided bulbs.

Myrobalan latent ringspot virus (MLRSV) was purified from the extract of infected Chenopodiumquinoa Willd., using n-octanol, differential centrifugation, and saccharose gradient centrifugation. Electron microscopy showed 28 nm large isometric particles in a sample of purified virus. Antiserum to MLRSV was prepared by immunisation of rabbits with intravenous injections of antigen in combination with intramuscular injections of antigen with Freund's adjuvant. The antibody titer of the obtained antiserum was determined by drop-precipitation method to be 1:1024. Immunoglobulins against MLRSV were isolated from antiserum with ammonium acetate, caprylic acid, and precipitation with ammonium sulphate. The isolated immunoglobulins (IgG) were conjugated with alkaline phosphatase. The optimal dilution of IgG for detection of MLRSV using ELISA was 1×10-3μg/ml which was also the optimal dilution of conjugated IgG. Using this dilution of antibodies, the absorbance of samples from MLRSV-infected plants of C. quinoa varied between 0.71 and 1.45, while absorbance of samples from healthy plants (control) was 0.01 to 0.07.

An important parameter for the characterization of microstructural changes in nickel base superalloys is the misfit - the relative difference between lattice parameters of γ matrix and γ′ precipitates. The misfit in IN738LC superalloy was examined at POLDI time-of-flight (TOF) neutron diffractometer both at room temperature and in situ at elevated temperatures using a high-temperature furnace. A careful out-of-furnace measurement yielded the lattice parameters of both γ and γ′ phase at room temperature (aγ=3.58611(10) Å, aγ′=3.58857(17) Å) as well as the misfit (equal to 6.9(6)×10-4). The in situ measurement at elevated temperatures provided the temperature dependence of the lattice parameters of γ (up to 1120°C) and γ′ (up to 1000°C). Using these data, the evolution of the misfit with temperature was calculated. The misfit decreases with increasing temperature until it reaches zero value at a temperature around 800°C. Above 800°C, it becomes negative.

Precipitation of γ’ phase in nickel-base superalloy IN792-5A was studied using in-situ Small Angle Neutron Scattering (SANS). It was found that additional precipitates are formed after reheating above 600 °C when the material is previously fast cooled (100 K/min) from 900 °C. The size distribution and volume fraction of the additional γ’ precipitates as well as of the already present medium-size precipitates in dependence on temperature were evaluated. The small precipitates can influence mechanical properties of the alloy, which exhibits an anomaly in the temperature dependence of the yield stress. Volume fraction of all precipitate populations above 900 °C was estimated as well.

Commercialisation of Biotech/GM (Biotech) crops started in 1995. Not only field crops, but also horticultural transgenic crops are under development and are beginning to be commercialised. Genetic engineering has the potential to revolutionise fruit tree breeding. The development of transgenic fruit cultivars is in progress. Over the past 20 years an international public sector research team has collaborated in the development of HoneySweet plum which is highly resistant to Plum pox virus (PPV) the most devastating disease of plums and other stone fruits. HoneySweet was deregulated in the USA in 2010. HoneySweet (aka C5) has been evaluated for eleven years (2002-2012) in a regulated field trial in the CzechRepublic for the resistance to PPV, Prune dwarf virus (PDV), and Apple chlorotic leaf spot virus (ACLSV), all of them being serious diseases of plum. Even under the high and permanent infection pressure produced through grafting, PPV has only been detected in HoneySweet trees in several leaves and fruits situated close to the point of inoculum grafting. The lack of infection spread in HoneySweet demonstrates its high level of PPV resistance. Co-infections of PPV with PDV and/or ACLSV had practically no influence on the quantity and quality of HoneySweet fruit which are large, sweet, and of a high eating quality. In many respects, they are superior to the fruits of the well-known cultivar Stanley. Many fruit growers and fruit tree nurseries in the CzechRepublic are supportive of the deregulation of HoneySweet plum to help improve the plum production and control the spread of PPV.

Results of research aiming at monitoring of climate changes impact on plant pathogens distribution such as Zucchini yellow mosaic virus (ZYMV), quarantine Plum pox virus (PPV) and quarantine phytoplasma European stone fruit yellows (ESFY) are presented here. ZYMV has spread from Northern Italy across Austria up to Central Moravia and Bohemia. PPV has been continuously spreading from the lowlands of Central Bohemia and Moravia up to plains. Later, from the sixties and seventies of the last century, due to climate warming and human activities the virus quickly spread to uplands, foothills and mountains of the Czech Republic. Phytoplasma ESFY was spreading in a manner similar to ZYMV in the eighties of the twentieth century from Northern Italy and currently is affecting mainly apricot and peach trees in Southern Moravia.

A survey on the occurrence of plum pox virus (PPV) in plums, myrobalans, blackthorns, apricots and peaches was carried out in the South Moravian region along the Austrian border. Results of tests by ELISA and evaluation of PPV symptoms showed only scattered or isolated occurrence of PPV. This situation can be used for gradual elimination of PPV in the South Moravian region.