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Fig. 3. Dynamics of the radionuclides content in Nyphar lutea L. from Glyboke Lake.

Fig. 4. Dynamics of the radionuclides content in Stratiotes aloides L. from Glyboke Lake.

It is obvious from Fig.10-12, that macrophytes from Glyboke Lake were most heavily contaminated with 90Sr. Other water objects from the point of view of radionuclide concentrations in aquatic plants could be ranged in following decreasing order: Daleke Lake and Krasnyans’ky Branch – Chornobyl NPP cooling pond – Prypyat’ river. Concerning decreasing of 137Cs concentrations that rank looked like Glyboke Lake – Daleke Lake – Krasnyans’ky Branch (except hornwort from cold section of cooling pond) – Chornobyl NPP cooling pond – Prypyat’ river.

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Fig. 8. Dynamics of the radionuclides content in Typha latifolia L. from Prypyat’ river (Chornobyl town).

Fig. 9. Dynamics of the radionuclides content in Ðotamogeton perfoliatus L. from Prypyat’ river (Chornobyl town).

Accumulation of radionuclides by different species of highest aquatic plants growing in water bodies of different types is affected by various factors. There is vegetation period, water pH etc. For example, while considering highest aquatic plants collected in August-September, it can be seen, that in isolated and stagnant water objects like Glyboke Lake and Krasnyans’ky Branch the maximal concentrations of 137Cs were observed in glyceria and the smallest ones were observed in reed mace. Maximal concentrations of 90Sr were found in Potamogeton Perfoliatus L. and Stratiotes aloides L. while minimal radionuclide concentrations were determined in sedge. High radiocaesium concentrations in glyceria could be explained with its growing in the water-bank line where according to our findings for isolated and

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macrophytes from these water objects was in the limits of (26 – 62)*103 and (24 – 58)*103 MBq correspondingly.

References

1.D.I. Gudkov, L. N. Zub, A.L. Savitskiy and others. Macrophytes of exclusive zone of Chernobyl NPP: formation of plant communities end peculiarities of radionuclide contamination under conditions of left riverbank floodplain of the Prypiat’ river. Hydrobiological Journal V.37, N 6, 2001, pp.64 -81 ( in Russian ).

2.A.E. Kaglyan, V.G.Klenus, V.V.Belyaev and others. Dynamic content of 90Sr and 137Cs in hydrobionts: higher aquatic plants of water bodies of the Chernobyl’ NPP 30km exclusive zone. Naukovi zapysky Ternopil’skogo peduniversytetu. Ser.: Biology, Special issue: Hydroecology. N4 (15), 2001, pp.14 -17 ( in Ukrainian )

EFFECTS OF RADIOACTIVE AND CHEMICAL POLLUTION ON PLANT VIRUS FREQUENCY DISTRIBUTION

V.P. POLISCHUK, T.P.SHEVCHENKO*, I.G. BUDZANIVSKA, A.V. SHEVCHENKO, F.P. DEMYANENKO, A.L. BOYKO

Virology Dpt., Taras Shevchenko’ Kyiv national university, 64 Volodimirska st., Kyiv 01033, UKRAINE

*Institute of Agroecology and Biotechnology of UAAS, 15 Metrologichna st., Kyiv, UKRAINE

e-mail: virus@biocc.univ.kiev.ua

1. Introduction

Remediation and exploration of soils in Chornobyl estrangement area also suppose growing of agricultural crops in the region. However, plants in this area are permanently under effect of the constant radioactive pressure [2]. Nowadays, it must be taken into account that stress might simultaneously have an abiotic (radioactive, chemical) nature and a biotic one as well. Virus infection can be an inducement of biotic stresses in plants. As we demonstrated in previous works, ionizing radiation can lead to mutations in plant organisms and in plant viruses, too. Owing to mutations’ accumulation, there is a possibility of new more pathogenic virus strains’ appearing. Arisen in Chornobyl region, these highly virulent strains can be spread over a large territory affecting agricultural crops’ yield [2, 3].

Similarly, increasing of heavy metals’ concentration as a factor of chemical pollution may lead to common, low-specific physiological and biochemical changes in plants, the most common from them could be membrane damages, changes in enzyme activity, inhibition of root growth, etc [1, 5]. The result of these interactions may be almost the same.

Research on the course of virus infections under the effects of radioactive and chemical pollution and monitoring for plant viruses circulation may reveal plants that are genetically resistant to virus infections, may help to explain the nature of plant virus strain diversity and allow to develop efficient protective measures.

2. Materials and methods

In our work we tested some local areas in Chornobyl region: Kopachy, Novoand Staro-Shepelichi (10-km zone), Chornobyl surroundings, Opatchichi, arid areas in Shepelichi and Buryakivka villages. Plants from the ecologically clean place in Shatsk National park were taken as controls . Gamma-radiation dose rates for regions to being compared were 300-520 µR/h and 5-10 µR/h for Chornobyl NPP contaminated area and ecologically clean territory of Shatsk National park, correspondingly. Plants were sampled on 15 points.

Also, we collected plant and soil samples for heavy metal content investigation using atomic absorbance spectroscopy (AAS) from two regions of Ukraine (Boguslav area in Kyiv region, and area of Zmiyivsky Power Plant in Kharkiv region) by the same procedure.

All samples were tested in indirect ELISA with polyclonal rabbit antiserums for the following viruses: TMV, PVX, PVY, PVM, PVS, PVF, PLRV, BYMV, AMV and

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CMV by the common method. Goat anti-rabbit IgGs conjugated with horseradish peroxidase were used as second antibodies, and H2O2 as a substrate [4, 9]. To stop reaction, we used 2Ɇ ɇ2SO4. Results were counted at the wavelength of 492 nm.

A spectrum of typical indicator plants was used to determine biological properties of viruses as follows: Chenopodium amaranticolor, Datura stramonium, Nicotiana tabacum cv. Samsun, N. glutinosa, N. tabacum cv. trapeson, N. debney³, N. sylvestris and Plantago major.

In order to study virus morphology, a JEM-1200 electronic transmission microscope was used.

3. Results and discussion

Our work was focused on the assessment of some plant virus distribution (TMV, PVX, PVY, etc.) in wild and cultural flora of Chornobyl NPP area in order to develop recommendations concerning the most efficient way of remediation of contaminated soils in this estrangement area.

Analysing some specimen of Elytrigia repens, Taraxacum officinale, Plantago major and Cirsium arvense, we could reveal serious differences between samples from Chornobyl and from other areas. Investigations in 2 fields near to the Opatchichi settlement showed that the plant virus frequency distribution was much higher in the case of Chornobyl samples comparing to control plants from Shatsk National park. It may be due to a decrease in protection reactions of plants growing under conditions of radioactive pollution, and to increase of virus infectivity as well. The most grim values were obtained for such pathogenic viruses as PVX, TMV and PVY which proves a need in careful monitoring for virus circulation to avoid their spreading over the agrocenoses of Ukraine.

Plant species diversity was much less abundant on the arid area comparing to normal forest. It was demonstrated that, similarly to Opatchichi area, plant virus frequency distribution was much higher in the case of Chornobyl NPP area samples comparing to control plants, which can reflect a level of radionuclide pollution or a seriously reduced quantity of plant species presented (Fig.1). It should be stated that previous sample analysis from different areas of the Chornobyl region (NovoShepelichi, Kopachi, Yanov, Buryakivka) proves the general tendency toward the increase of epiphytothic background (i.e. increased ability of viruses to infect plants) in agrocenoses and biocenoses as well. Moreover, viruses extracted from plants in this region developed non-typical symptoms on the corresponding indicator plants.

Frequency distribution was much higher for the majority of viruses investigated in Chornobyl samples even comparing to unexploited areas of other regions including Kharkiv with serious level of chemical pollution, especially with heavy metals pollution. The purpose was to check the dependence between increased heavy metals content in soil and its influence on the course of virus infection in plants growing on Ukrainian agrocenoses [6].

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Fig. 1. Virus antigens’ presence in regions differing in radioactivity pollution.

Experiments conducted in relation with heavy metal (cadmium, lead, copper, zinc and nickel) soil content have shown their different concentrations in the regions investigated (Fig.2). Contrary to Kyiv region and control area of Shatsk National park, Kharkiv region had remarkably high level of pollution with these heavy metals regardless of the almost similar absorbing capacity of soils of these regions [10]. Obviously, increased heavy metal concentration in the area of Zmiyivsky Power Plant (Kharkiv region) mainly is due to the activity of the power plant.

Much more frequent revealing of TMV, BMV, CMV and PVY antigens was typical for this region (Fig.3). Together with heavy metals, adsorption of virus particles also depends on the soil features such as mechanical structure, pH, etc [8]. The ecologically clean area of Shatsk National park was comparatively free from virus antigens possibly owing to differences in soil structure and to the less obvious anthropogenic pressure. Although, comparing distribution of virus antigens in Kyiv and Kharkiv regions we revealed their higher concentration in Kharkiv despite the same soil structure and its absorbing capacity [11].

Modeling experiments using TMV-Nicotiana tabacum system were conducted in order to determine the effect of virus infection on plants grown in soil with higher content of heavy metals (copper, lead and zinc soluble salts), which corresponded to the estimated level of Kharkiv region [11] and was higher in comparison to maximum permissible concentrations determined for these metals in Ukrainian soils [7, 12]. Visually, control plants grown in sterile non-polluted soil looked absolutely normal, whereas plants grown in soil with heavy metals added developed stunting (Fig.4). Virus-infected plants grown in non-polluted soil demonstrated the development of typical disease symptoms (leaves deformation, enations, yellowing) in two weeks post infection. Infected plants grown in the polluted soil clearly showed a disappearing of virus infection symptoms in 10 days post infection, and died in 20 days post infection (dpi).