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Fayziyev Vahid Bakhramovich, Candidate of biological sciences Associate Professor of Chirchik State Pedagogical Institute, Tashkent Region E-mail: [email protected] Vakhabov Abdurasul, Professor, National University of Uzbekistan named after Mirzo Ulugbek E-mail: [email protected]
THE STUDY OF THE BIOLOGICAL PROPERTIES OF POTATO VIRUS X IN COMMON ENVIRONMENTAL CONDITIONS OF UZBEKISTAN
Abstract. In recent years, PVX has been widely spread in Uzbekistan's climatic conditions, causing symptoms of the disease, like spotty mosaic and curling of potato leaves. The appearance of signs of this viral disease depending on environmental factors, especially temperature, contributes to the fact that it begins to meet in a latent state at a high temperature in the climatic conditions of Uzbekistan, remaining in the nodules of potatoes, causes a decrease in yields every year to 10-59%. Therefore, the extent of the spread of this virus in the climatic conditions of Uzbekistan, natural reserve reservoirs, have been studied by the highly sensitive ELISA method. Based on studies conducted in this direction it was found that the extent of the spread of this virus was initially 16.65%, and in subsequent studies it increased to 24.06%. At the same time, in the climatic conditions, reserve plants such as Solanum nigrum L., Rumex crispus L., Datura stramonium L., Solanum melongena L., Convolvulus arvensis L., Althaea officinalis L., Malva neglesta Wall were first established by the ELISA method.
Keywords: PVX, enzyme linked immunosorbent essays (ELISA), plant reservations, Tashkent, Uzbekistan.
1. Introduction remnants ofvarious organs of such plants in the soil layers can
Over 20 species of viruses have been identified world- serve as "natural foci" of viral diseases [4; 6]. A. L. Ambrosov, wide, causing potato diseases and each of them differs accord- I. T. Ergashev and a number of other authors have experimen-ing to the pathological symptoms observed in the plant and tally proved that such wild plants as S. nigrum, D. stramonium, economic damage [4]. A number of such pathogenic viruses C. arvensis [9], and in Uzbekistan N. N. Babrishev proved that can include the X-virus of potato, which, depending on potato L. esculentum and C. annum cultivated plants are hidden reservarieties, environmental conditions and strains of the virus, voirs of X, S and M (K) - potato viruses. The degree of their reduces the yield to 10-59% [2; 4; 11; 15]. This virus is con- spread, as well as natural reserves differ from each other in the sidered one of the dangerous viruses, seriously threatening type ofvirus, carrier and environmental conditions [7; 8; 18]. potato yields worldwide and planting resistant varieties of po- Therefore, a study ofthe extent of spread and natural reserve tatoes that lead to a minimum harm from the influence of the plants PVX using a highly sensitive, rapid and reliable method virus [13]. PVX belongs to the genus Potexvirus and known (ELISA) is important in developing measures to control the vistrains such as PVX HB [10; 12] and the newly discovered rus and eliminate inaccurate results obtained with low-sensitivity PVX [4; 21] and PVX Tula [12; 19]. The virus is in many methods. This article is aimed at studying this issue. cases stored in nodules, reduces yields year after year and is 2. Materials and Methods
distributed mechanically and with the help of carriers (vec- The main materials for the study - antibodies of potato
tors) - insects [5]. viruses (AT (IgG)), conjugate (IgG + enzyme), polystyrene
In many cases, it does not cause symptoms of the disease plates and chemical reagents were obtained from the organiza-
in plants and is latent, but can cause chlorosis, mosaic and a tion "International Center of Potato".
decrease in the size of the sheets. This virus is found with other To diagnose potato viruses using IFA, the following
viruses (PVY and PVA) and the disease can take a serious na- were used:
ture and this leads to a catastrophic decline in yields [4; 6; 17]. - a specific antiserum prepared on the X potato virus (IgG);
To combat such pathogenic viruses, the focus should be - Polystyrene boards;
on their "natural foci" [6; 7]. Various diseased plants and the - conjugate (IgG + enzyme);
- Buffers (phosphate buffer (composition for 1 liter of distilled water: 8 g NaCl, 0.2 g KH2PO4, 1.15 g Na2HPO4, 0.2 g KCI, 0.195 g NaN3) twin phosphate buffer PBS-T), buffer for grinding sample (0.4 g PVP-40.000, 2.0 g egg albumin), conjugate buffer (4.0 g PVP-40.000, 0.04 g egg albumin), substrate buffer;
- clean dishes;
- polyethylene bags for samples;
To determine the viruses, the organs of plants (leaves, stem, root) with the primary signs of the disease were separately packed into polyethylene bags and with the addition of phosphate buffer (composition for 1 liter of NaCl, KH2PO4, Na2HPO4, KCl, NaN3, pH-7.4) and a homogenate was prepared. Then, viral AT (igG) was immobilized in polystyrene plates at 37 °C for 3-4 hours or at room temperature for 5-6 hours, excess of AT (20 drops (0.5 ml) were added to 1 liter of the prepared phosphate buffer) Tween PBS-T) is washed off with Tween phosphate buffer, homogenate is added from the organs of the plant under study (AG) and stored for 3-4 hours in a
As a result of preliminary studies of samples obtained in Kibray district, the level of PVX distribution in the area was maximum 5%, and secondly, two years after repeated studies, it was found that the level ofvirus spread increased from 5 to 90%.
As a result of studies, conducted by the Parkent district, at first, the spread of the virus in this area was 5-20%; as a result of repeated studies, the virus was not detected.
thermostat at 37 °C. After a certain time, the vegetable juice is washed using a specially designed for washing Tween phosphate buffer and after the conjugate is placed in the microplate of the poly styrene plates, the latter are placed polyethylene bags and stored for 3-4 hours at 37 °C or can be left for 5-6 hours at room temperature 25 °C). The excess conjugate (IgG + enzyme) is washed with Tween Phosphate Buffer (RVS-T) and 50 ^l substrate (diethanoamine, 37% HCl), distilled water and substrate tablet (p-nitrophenyl phosphate) are poured into each well of polystyrene plates. When viruses are present in the plants under investigation for 30-60 min, they are detected by a change in the color of the reaction, and the results are taken into account.
3. Results аnd discussion
For investigation of PVX distribution level in Tashkent region samples (leaves) of potato plant were separately collected from Kibray, Parkent, Tashkent and Zangiota districts, for four in one district, from 15 village communities, checked by ELISA method in laboratory condition and obtained results given in the table (1 table).
In Tashkent district, in a preliminary check, the spread of the virus was 5-50%, after two years after repeated studies it was revealed that the level ofspread ofthe virus decreased by 5-15%.
In the Zangi-Ota area, in both studies, it can be observed that the spread of the virus has not changed much; detailed information about this is given in the table (1-table). Based on the obtained results, the average level of virus spread in
Table 1. - Determination of sickness rate of potato sorts in Tashkent region by PVX virus with the help of ELISA method
№ District Names of farms First assay Second assay
Potato kinds Area, ha Morbidity rate.,% potato varieties Area, ha Morbidity rate,%
1. Kibray Kibray agrocomplex Ditta 6.0 5.0 Desire 4.0 90.0
2. Jaydakbayev Edil Desire 3.5 0 Desire 1.0 70.4
3. Kibray Mixed 1.0 0 Ditta 8.0 5.4
4. Parkent Baykazam Jam-plus Santé 0.7 10.2 Santé 1.0 0
5. Baykazam Valid plus Santé 1.0 20.3 Santé 0.5 0
6. Baykazam tarnovi Romano 1.5 5.0 Santé 1.5 0
7. Oqul Orzu rivoji Ditta 1.0 35.0 Ditta 1.0 0
8. Tashkent Abdurakhmon Foody 1.5 15.5 Marphona 3.0 0
9. Gulnoza Fayz-baraka Foody 1.0 5.4 Foody 2.0 15.0
10. Murad agro-plus Foody 2.0 30.0 Nevsky 3.0 15.7
11. Batko agro-plus Foody 7.0 50.0 Nevsky 3.5 5.4
12. Zangi-ota Dustov Yuldash Foody 2.0 10.3 Foody 3.0 20.5
13. Yulchi Khamid Romano 1.0 0 Foody 4.0 20.3
14. Yunusov Bakhrom Foody 1.0 50.0 Foody 1.5 55.2
15. Okul Orzu rivoji Foody 1.5 30.6 Nevsky 1.5 25.0
Note: "0" means absence of virus in the table
the regions of the region was revealed and given in the form of a histogram (figure). The figure shows that in the Kibray region of the region, compared with the results of preliminary studies in subsequent studies, the spread of the virus increased dramatically, i.e. increased by 50%. According to a number of researchers who conducted research in this direction, the cultivation of potato-infected tubers for many years led to the wide spread of the virus in one field. The same situation is observed in this area, i.e. the re-cultivation ofvarieties such as
ditta and desire for three years (table 1) led to the large-scale spread of the virus in these farms. In Parkent and Tashkent, areas where a decrease in the spread of the virus was observed, phytosanitary measures were carried out in a timely manner in potato fields and potato seeds were annually updated (figure). In the total area studied (31.7%) of Tashkent region, 50.4% of the field (16.1 ha) were sown with the local variety Tuyimli, and foreign varieties such as Ditta, Desiree and Ramona were grown for the remaining 40.6%.
Fifure 1. The prevalence of PVX in areas of Tashkent region
Natural reserves play an important role in the spread of viruses. A number of wild and cultivated plants can be attributed to natural reserves of phytoviruses and these plants occupy an important place in the spread of viruses [6; 9]. Therefore, in
the following studies, the fields of rural farms with a high level of distribution and 27 species of wild and cultivated plants in the vicinity of these fields were studied using the ELISA method and the results are shown in the table (table 2).
Table 2.- Determination of PVX Reserve Plants by ELISA
№ Plant names Reaction rate
Species Family
1 2 3 4
1. Cynodon dactylon (L.) Pers. Gramineae -
2. Cyperus rotundus L. Сyperaceae -
3. Cucumis sativus L. Cucurbiteceae + + + +
4. Atriplex micrantha C. A. Mey. Chenopodiaceae -
5. Sorghum halepense L. Gramineae -
6. Solanum nigrum L. Solanaceae +
7. Artemisia vulgaris L. Compositae -
8. Chenopodium amaranticolor Chenopodiaceae +
9. Rumex crispus L. Poiygonaceae + + +
10. Datura stramonium L. Solanaceae ++
11. Solanum melongena L. Solanaceae + +
12. Capsicum annuum L. Solanaceae -
13. Brassica juncea Czern Cruciferae +
14. Mentha asiatica Boriss Labiatae +
15. Solanum tuberosum L. Solanaceae (Diyora kind) +
16. Solanum tuberosum L. Solanaceae (Umid kind) + + +
1 2 3 4
17. Solanum tuberosum L. Solanaceae (Aqrab kind) + + + +
18. Chenopodium quinoa L. Chenopodiaceae -
19. Convolvulus arvensis L. Convolvulaceae + + +
20. Ocimum basilicum L. Labiatae -
21. Amaranthus retroflexus L. Amaranthaceae +
22. Sinapsis arvensis L. Cruciferae +
23. Althaea officinalis L. Malvaceae + + + +
24. Lycopersicum esculentum Mill. Solanaceae + + + +
25. Alhagi adans Leguminosae -
26. Malva neglecta Wall. Malvaceae + + +
27. Artemisia vulgaris L. Composita -
Note: in the table means"-" - the reaction is absent, "+" - the and "++++" - the very strong reaction.
As can be seen from the table, the X virus can exist in addition to potatoes in plants such as Cucumis sativus L., Solanum nigrum L., Rumex crispus L., Datura stramonium L., Solanum melongena L., Petunia hybrida, Convolvulus arvensis Althaea officinalis L., Lycopersicum esculentum Mill., Malva neglesta Wall and these plants have a very high virus content (3+ and 4+). In addition, the virus can multiply in plants such as Solanum nigrum L, Ch. amaranticolor, Brassicajuncea Czern., Mentha asiatica Boriss, but in small quantities. In Cynodon dastylon (L.) Pers., Xanthium strumarium L., Sorghum halepense L., Capsicum annuum L., Ocimum basilicum L., Artemisia vulgaris L. In Artemisia vulgaris L., the virus was not detected (Table 2).
Based on the above data, under the climatic conditions of Uzbekistan, PVX infects single and perennial plants of the families Solanaceae, Malvaceous (Malvaceae), cruciferous (Cruciferae), amaranth (Amaranthaceae), complex flowers (Compositae) and accumulates in large quantities. This means that these plants undoubtedly serve as PVX reserve plants.
In general, potato viral diseases have been studied since 1916 in England, Holland, USA, Germany, Russia, Estonia by such scientists as Quiner, Boties, Schulz, Folsom, Cassanis, Martin, Yora, Morel and Ambros [4; 2; 3; 8], but studies conducted in the conditions of Uzbekistan were carried out only at the level of the plant-indicator, by the drop method and on the sensitivity of the ABC test (0.2 ^g / ml). Many reserve plants and a small amount of viruses in potato varieties remained outside the sensitivity level of the method. In this work, highly specific titrated antiserum was used [3], the sensitivity level of which is 0.01-1 ng and prepared only for this virus.
Many plants are asymptomatic and analyzed for the first time. For example, the plants first analyzed are Cucumis sativus
reaction is weak, "++" - the average reaction and "+++" - the strong
L., Rumex crispus L., Brassica juncea (L.) Czern., Althaea officinalis L., Malva neglesta Wall and their PVX content is high. It means, undoubtedly, these plants are introduced into a number of plants-reservers for PVX for the first time in phytoviru-sology in the climatic conditions of Uzbekistan.
On the basis of the identification of these plant-reserve plants, the regularity of the PVX-Uz cycle in nature and the type of "natural focus" were revealed. According to the theory of E. N. Pavlovsky on "Natural foci of vector-borne diseases" [22] the natural focal type of this virus belongs to the second type, i.e. to the type of "naturally focal diseases with a stable circulation within cultivated plants." Despite the existence of a number of plants that reserve the virus in nature, they are transmitted through nodules from generation to generation and there remains a strong link between the pathogen (virus) and the cultivated plant (potato).
4. Conclusions
Thus, in the climatic conditions of Uzbekistan, the presence of a number of natural plant-reserving agents, such as Cucumis sativus L., Rumex crispus L., Brassica juncea Czern., Althaea officinalis L., Malva neglesta Wall, D. stramonium L., D. metel L and with the fact that the virus belonged to natural foci, it was found that they belong to the type of "natural circulation within cultivated plants".
At the same time, the distribution of PXV in the Tashkent region was studied by ELISA, one of the most sensitive methods. According to the results of the study, the spread of the virus in the Kibray district of the Tashkent region increased to 50% compared with initial surveys, while in the Parkent region there was a noticeable decrease in the number of viruses.
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