[en] A reliable protocol for regenerating barley from seedling explants, including leaf bases with a complete apical meristem, has been developed at the Institute of Genetic Engineering. The system was established with Bulgarian barley cultivars (Ruen, Karnobat, Obzor and Yubilei) and reconstructed genotypes (K. Gecheff IG). Pretreatment of the mature embryos with a high concentration of 2.4D generated valuable and stable genetic deviations in the regenerants. The brewery cultivar Ruen was selected as the model genotype. It has been demonstrated that genetic variations, such as higher yield, earlier maturation and lower protein content, have been induced and maintained for 5 years. Comparative experiments, including treatment of barley mature seeds with ⁶⁰Co gamma rays (10 and 20 krad) and sodium azide (1.10^-3 M and 5 x 10^-4 M), were also carried out. The results obtained showed that both treatments stimulated calusogenesis and regeneration of the plants. Molecular markers such as proteins, restriction fragment length polymorphisms (RFLPs) and random amplified polymorphic DNAs (RAPDs) were applied in studies on the mutagenic effects of 2.4D, gamma rays and sodium azide, and a combination threof, on the quality and quantity of the genetic diversification generated in tissue culture of the Bulgarian barley cultivars Ruen, Karnobat, Obzor and Yubilei and the reconstructed genotypes

[en] Barley, Hordeum vulgare L., is one of the most important crop species for Bulgaria. The characterisation of the genetic pool is of great necessity for the Bulgarian barley breeding programme which is directed toward improving quantitative and qualitative traits. Molecular markers [protein, restriction fragment length polymorphisms (RFLP) and randomly amplified polymorphic DNA (RAPD)] have been applied to characterise the Bulgarian barley cultivars and their regenerants. The changes in DNA loci coding for 26S, 5.8S and 18S rRNA repeats, C hordein locus and mitochondrial DNA organisation have been investigated. The potential for ribosomal DNA length polymorphism in Bulgarian barley cultivars appear to be limited to three different repeat lengths (10.2, 9.5 and 9.0kb) and three plant rDNA phenotypes. Polymorphism was not observed in ribosomal DNA repeat units in somaclonal variants. Variation concerning C hordein electrophoretic pattern was observed in one line from cultivar Jubiley. Analysis of the HorI locus reveals RFLPs in sequences coding for C hordeins in this line. Mitochondrial molecular markers are convenient for detection of DNA polymorphisms in the variant germplasm as well as for the somaclonal variants derived from it. Two lines from Ruen revealed polymorphic bands after hybridisation with mitochondrial DNA probe. RAPD assays have been carried out by using 20 different 10-mer primers. Heritable polymorphism in several tissue culture derived (TCD) lines was observed. RAPD assay is a sensitive and representative approach to distinguish the variability created by tissue culture and mutagenesis

[en] Avian influenza (AI) is a highly contagious viral disease affecting several species of food producing birds (chickens, turkeys, quails, guinea fowl, etc.), as well as pet birds and wild birds. The AI viruses are divided in two groups based on their ability to cause disease (pathogenicity). Highly pathogenic avian influenza (HPAI) virus spreads rapidly, may cause serious disease and result in high mortality rates (up to 100% within 48 hours). The low pathogenic avian influenza (LPAI) can causes mild disease that may be undetected or no symptoms at all in some species of birds. Since 1997 millions of chicken have been reported to have died due to HPAI H5N1 in countries of South-East Asia. In 2003 AI virus H7N7 affected poultry farms in Netherlands, then penetrated to Belgium and Germany. It had been considered that among human community there were circulating A viruses of 3 subtypes of H type (H1, H2 and H3) and 2 subtypes of N type (N1 and N2). However, for the recent years it has established that AI viruses as a result of mutation have changed their biological features and acquired a capacity of overcoming an interspecies barrier and affecting humans, mostly with lethal outcome. Once domestic birds are infected, avian influenza outbreaks can be difficult to control and often cause major economic impacts for poultry farmers in affected countries, since mortality rates are high and infected fowl generally must be destroyed -- the technical term is 'culled' -- in order to prevent the spread of the disease. Anatidae (ducks, geese and swans) is a group of water birds that is ecologically dependent on wetlands for at least some aspects of their annual cycle. Anatidae species use a wide range of wetlands, from the high arctic tundra, rivers and estuaries, freshwater or saline lakes, and ponds or swamps to coastal lagoons and inter-tidal coastal areas such as mud-flats, bays and the open sea. They also utilize man-made wetlands such as rice fields and other agricultural areas. Many of the Anatidae populations migrate between wetlands in the northern breeding areas and southern non-breeding areas and in doing so, regularly cross the borders of two or more countries. During the expansion of HPAI (H5N l) outbreaks from Asia to Europe, 2 events implicated wild birds, particularly waterbirds, as long-distance virus vectors. First, virus outbreaks in 2005 rapidly spread westward from Russia and Kazakhstan in July and August to Turkey, Romania, and Ukraine in October.There have been further reports of H5N1 avian influenza infection in birds in Russia, the Middle East, the Caspian Sea, Azerbaijan, a swan in Maribor, Slovenia, wild fowl in Krasnodar and Dagestan,, and further cases in swans in Italy. There have been reports of H5 avian influenza infection in swans in Slovenia, Austria, and Hungary. It is not yet known whether these swans were infected with the H5N1 strain. Wild water birds were suggested as a vector because the virus spread through areas that had no record of any virus presence and coincided with the fall migration of wild water birds between these areas. Second, at the beginning of 2006, HPAIV (H5N1) was detected in many wild water birds in East Europe, often in areas where no outbreaks had been detected among intensively surveyed poultry; this event overlapped with unusual water bird movements associated with cold weather in the Black Sea area. Quantitative analysis of the global spread of HPAIV (H5N1) also supports the potential role of migratory wild birds in virus spread. migratory path of wild birds and the Black Sea cost, The national early warning and surveillance system also was adapted and covered these risk areas on the basement of periodic risk assessment. Two well equipped laboratories in Sofia and Varna covered the needs of samples investigation and research activities for AI of the whole territories of the country. The national surveillance plan includes domestic and wild bird populations and domestic (back yards) and producing big farm livestock populations as well. Based on the risk analysis, we think that future research studies should focus on the populations of several species wild migratory ducks, wintering at Shabla Lake (district of Dobrich), Varna- Beloslav Lake (district of Varna) and the wetlands Poda connected with Mandra Lake (district of Burgas). This surveillance will include marking of the caught birds in order to monitor their AI status in case they are caught again. The three lakes have been selected based on the advice extended by the Bulgarian Society for the Protection of Birds (BSPB) Varna. The selection of the lakes was based on their hydrologic features so that placing of ornithological nets for catching ducks to be possible (Some lakes do not allow access by boat or freeze in the winter)

[en] Effective use of experimentally induced mutants in breeding programs is highly dependent on the type of the induced mutations. The main goal of the present study is to reveal the molecular nature of ionizing radiation-induced mutational alterations in a stock of originally produced barley structal mutants. Biochemical and molecular tools were applied for obtaining more detailed information about the nature of gamma-rays induced genetic variation in the structural mutant forms (T-16, T-20, T-26, T-48, T-58, T-59, T-63, T-66, T-67, T-68, T-169 and RK 88-4) and their initial parental lines (cv. Freya and T1586). Among the marker systems used (PAGE, RFLP, CAPs, RAPD, REMAP, S-SAP, SSR and AFLP) SSRs and AFLPs have proven to be the most promising markers for evaluation of the ionizing radiation-induced mutational alterations in structural barley mutant forms. AFLP polymorphisms were observed in 2 cases using PstI/MseI and in one case using EcoRI/MseI, out of 20 selective AFLP primer combinations tested. Microsatellite analysis using 26 markers selected from the published barley genetic maps showed new allele variants in mutant lines T-20 and T-68 at the HVM 04 - 7HS locus and in mutant line RK 88-4 at the HVM 03 - 4HL locus. The observed polymorphisms in the above mentioned mutant lines are most probably caused by point mutations either in the respective restriction sites or in the microsatellite repeat or in the vicinity of the adjacent DNA sequences. (author)

[en] This report describes the history and current status of avian influenza (AI) infection and control in Bulgaria. The country has a unique geographic position in Europe with regard to wild bird populations and their migration routes which pass through its territory. In recent years, Bulgaria did not remain free from AI. The region with the highest rate of isolation of H5N1 virus strains were the Black Sea coast and wet territories connected with the Via Pontica migration pathway in the administrative districts of Dobrich, Varna and Bourgas. Low pathogenic (LP) AI strains isolated from ducks were subtypes H3, H4 and H6 from the areas of Plovdiv, Pazardjik, St. Zagora, Yambol, Sliven and Haskovo. Raising ducks for liver production is a popular practice in south and southeast Bulgaria. From an epidemiological standpoint, controlling circulation of AI viruses among duck flocks, especially before their gathering in larger farms for fattening is a mandatory requirement of official authorities. To prevent the spread of highly pathogenic (HP) AI, surveillance of domestic poultry as well as wild birds should be strengthened in countries at risk, especially along bird migration routes. Monitoring, sampling and analysis of the viral subtypes of AI found in wild birds needs to be carried out to fully understand their role in the propagation and spread of HPAI viruses. (author)

[en] Single Sequence Repeat (SSR) and Amplified Fragment Length Polymorphism (AFLP) markers were used to survey gamma ray induced genetic variation in a set of 13 originally produced structural barley (H. vulgare L.) mutants from cv. Freya; including 8 single translocation lines, 3 double translocation lines and 2 multiple reconstructed karyotypes. Both marker systems contributed to the evaluation of the radiation induced DNA alterations and revealed in general 0.49% polymorphisms in the studied genotypes. AFLPs were observed with 3 out of 10 PstI/MseI primer combinations. Transmissible microsatellite instability at loci with perfect (AT)n repeats located in the introns of the rubisco activase and waxy was documented in three mutant lines. The results emphasize that in addition to point mutations, small indels (2bp) form the major group of the gamma induced DNA alterations. (author)

[en] The response of tobacco plants (Nicotiana tabacum L.)-non-transformed and transformed with a metallothionein gene MThis from Silene vulgaris L. - to increase cadmium supply in the nutrient solution was compared. The transgenic plants accumulated significantly more Cd both in the roots and the leaves. Visual toxicity symptoms and disturbance in water balance were correlated with Cd tissue content. Treatment with 300 μM CdCl₂ resulted in inhibition of photosynthesis and mobilization of the ascorbate-glutathione cycle. Treatment with 500 μM CdCl₂ led to irreversible damage of photosynthesis and oxidative stress. An appearance of a new peroxidase isoform and changes in the leaf polypeptide pattern were observed at the highest Cd concentration. The level of non-protein thiols gradually increased following the Cd treatment both in transgenic and non-transformed plants. - Genetic transformation of Nicotiana tabacum L. by metallothionein gene improved phytoaccumulation of cadmium