Suchergebnisse

Results of monitoring of the population ofBlumeria graminisf.sp.hordeiin Latvia in 2009-2010In 2009-2010, random samples of the causal agent of barley powdery mildew were collected in Daugavpils (south-eastern Latvia, Latgale region), Stende (north-western Latvia, Kurzeme region) and Priekuļi (north-eastern Latvia, Vidzeme region). Virulence frequency, complexity and pathotypes were calculated in the pathogen populations. Significant differences of virulence detected by the genesVa1, Va3and Va13occurred among samples of the pathogen population collected in different parts of Latvia. Nei index, Müller's index, Kosman index, Shannon index and Simpson index showed considerably higher diversity in Daugavpils and Stende during 2009-2010. In Daugavpils, the population ofBlumeria graminisf.sp.hordei was particularly characterised by high diversity.

Implementation of a limited set of SSR markers for screening of genetic variability in Latvian and Swedish sour cherry (Prunus cerasusL.) genetic resources collectionsForty-one sour cherry (Prunus cerasusL.) accessions were evaluated using three SSR markers to characterise genetic diversity in the sour cherry genetic resource collections at the Latvia State Institute of Fruit-Growing (LIFG), Dobele, Latvia and the Division of Horticultural Genetics and Plant Breeding at Balsgård, Department of Crop Sciences, Swedish University of Agricultural Sciences (SLU-Balsgård), Sweden, and to test the usability and reliability of a small set of SSR markers for preliminary characterisation of sour cherry germplasm collections. The SSR loci were highly polymorphic with 7-14 alleles per locus. Heterozygosity and Polymorphic Information Content values ranged from 0.750 to 1.000 and 0.748-0.899, respectively, while discrimination power per locus varied from 0.716 to 0.965. Five to thirty genotypes were found in the sour cherry collections for the three tested SSR loci. The combined discrimination power of all loci was effectively 0.994 and 0.999 for the LIFG and SLU-Balsgård collections, respectively. The SSRs used were able to uniquely identify all accessions in the analysed genetic resources collections. The genotype data allowed estimation of genetic diversity and genetic characterisation of accessions in the collections. Genetic similarity analysis showed higher genetic similarity among the Baltic and Scandinavian sour cherry varieties, than between Baltic and Eastern European varieties.

Comparative analysis of sweet cherry (P. avium) genetic diversity revealed by two methods of SSR marker detectionThree previously described highly polymorphic SSR (microsatellite) primer pairs in 126 sweet cherry (Prunus aviumL.) accessions were tested using two microsatellite marker detection methods: ASCE (automated sequencer capillary electrophoresis) and PAGE (polyacrylamide gel electrophoresis) in screening of sweet cherry germplasm collections. It was determined that ASCE provided more precise genotyping. In the case of PAGE, due to possible manual scoring errors, a higher number of putative alleles was observed, which overestimated the level of polymorphism and hence the genetic diversity. This should be taken into account when comparing results obtained in different investigations. The ASCE detection method generally is considered as expensive, it requires more advanced and expensive equipment, and is available mostly in mid- to high-throughput laboratories. Nevertheless, the detection precision and possibility of complete unification of laboratory protocols among laboratories makes it a very useful tool in the identification and characterisation of sweet cherry breeding material, especially in large, diverse collecions.

Abstract
Samples of Limecola balthica with normal and deformed shells were collected from ten sites throughout the Gulf of Riga. Genetic diversity was evaluated by the retrotransposon-based iPBS method. Samples had close mutual genetic distances, which showed that all of them belong to one wider population of the Gulf of Rīga. No direct relationship between the activity of retrotransposons and deformation of shells was found.

Abstract
Sprouts of diploid red clover 'Stendes Agrais' were treated with 0.2% colchicine solution. The ploidy level of plants was detected by flow cytometry. Most of the treated plants were mixoploids and sterile. From progenies of fertile plants, mixoploids were selected that had a proportion of tetraploid cells higher than 60%. In the next generation, stable tetraploid plants were selected, and 49 lines were included in the breeding process.

Abstract
The paper presents the results of combined effects of an extremely low frequency electromagnetic field (50 Hz) (ELF EMF) and SiO2 nanoparticles on fluorescence of plant gametic cells (immature microspores). The data were recorded by a BD FACSJazz® cell sorter after cell irradiation by blue laser (488 nm). A significant difference of fluorescence was observed between gametic cells after 1 hour incubation in suspension of SiO2 nanoparticles and the control gametic cells. It was observed that fluorescence intensity of gametic cell was higher with ELF EMF treatment in comparison to control cells, but it was statistically significant only for cells treated with electromagnetic radiation field with density 100 μT (ρ < 0.01) and 400 μT (ρ < 0.01). A different effect of ELF EMF were observed in cells incubated in SiO2 nanoparticle suspension; interaction of the factors resulted in lower cell fluorescence in comparison to control cells. The present study showed that SiO2 nanoparticles may be a source of oxidative stress, but jointly with 50 Hz electromagnetic field they can serve as an efficient antioxidant

Accessions with no germinating seeds are a common problem in plant gene banks and research institutions. Our goal was to elaborate and apply an in vitro method of germination and multiplication of old aged seeds of red and alsike clover and alfalfa. Eighteen clover and five alfalfa accessions were used for germination in vitro. Most of the accessions had produced seeds more than 20 years ago and the seeds did not germinate in soil. Seed pre-treatment with different concentrations of potassium permanganate, as well as addition of phytohormones, AgNO3 and activated carbon to germinating media were tested. Plantlets for all germinated accessions were obtained, even in the case when seeds were 44-year-old (alfalfa). Germination rate in vitro not always correlated with seed age and ranged from 2 to 72%. Pre-treatment with potassium permanganate was effective both for seeds sterilisation and germination stimulation. Most germinated seeds formed phenotypically normal seedlings with all organs. In vitro multiplication of obtained clover plants was performed. Best results were achieved by micropropagation of stem segments approximately 2 mm in length. Number of finally obtained plants depended not only on seed germination ability, but also on micropropagation ability in relation to genotype, and on acclimatization success in soil after in vitro cultivation

Abstract
Mute swan Cygnus olor is the most abundant breeding swan species in Rīga and Latvia. Since manmade habitats are the preferred breeding habitats of this species - Cygnus olor is of particular interest in studies of urban biodiversity. The latest records show that 30-40 pairs breed annually in Rīga, 400-700 individuals migrate through the area, and 120-150 individuals stay over winter. The goal of our study was to determine the genetic variation of the mute swan population in Rīga. Blood samples were collected from 47 individual birds found in different sites in Rīga or elsewhere in Latvia. The universal retrotransposon based iPBS markers were used to estimate diversity. Three primers (2076, 2080, and 2415) amplified 64 DNA fragments; of these 18 (28%) were polymorphic. The average diversity index based on polymorphic markers for the studied individuals was 0.425. All individuals, with the exception of two pairs of individuals, could be separated by means of these markers. The grouping of individuals was not be associated with their sampling location, gender and age. The genetic diversity indexes were compared between these groups. The breeding individuals (including their cygnets) had bands not showing variation among breeding birds as compared to the not breeding ones.

Abstract
White clover (Trifolium repens L.) is well represented in the urban environment and wide areas. The goal of this study was to compare the genetic features and to determine the genetic distances and similarities between some populations of white clover using iPBS (inter primer binding sites) technique in a retrotransposon-based method in samples from ecologically different areas in Latvia. Comparisons were made between three plant groups: urban environment (different areas in Rīga), Latvian countryside territory (four different localities), and the commercial variety 'Daile'. The Shannon diversity index was not high (0.2974 for Rīga, 0.3079 in countryside territories, and 0.3367 for the variety 'Daile'), but the polymorphic bands present in all evaluated plant sets were higher than 89%. Using principal coordinates analysis the white clover formed three clusters. One cluster included plants from the variety 'Daile'. The plants from Rīga urban area and different sites of Latvia formed two clusters.

Genetic profiles and diversity of Baltic spring barley material
The objectives of this study were to generate molecular passport data for identification and differentiation of Baltic spring barley accessions (cultivars, landraces and breeding lines) and to estimate the genetic variation within and among these accessions. Allelic profiles of 21 microsatellite and 8 isoenzyme loci were obtained and analysed for 64 Baltic spring barley accessions. The microsatellite data was successfully used to separate all of the accessions by individual allelic pattern and frequencies, whereas only 30 of the studied accessions could be distinguished by isozyme data. Variation was detected both among and within the accessions and was significant. The variation within accessions accounted for 20.6% and 14.3% of the total variation, based on microsatellite and isozyme data, respectively. The six-rowed and two-rowed material was well differentiated by both types of marker data: according to AMOVA this differentiation accounted for 16.9% of the microsatellite variation and 26.8% of isozyme variation. Differentiation of accessions based on the country of origin could be detected only by isozyme markers and accounted for 9% of the total izozyme variation. Both isozyme and microsatellite data showed that accessions of Latvian origin had the highest total diversity values, while material from Estonia was the least diverse.

Abstract
The unique biological properties of amber are well known. Amber particles that penetrate into the cellular matrix can potentially be used as markers of plant cell biological activity by identification of living cells in flow cytometry. However, there have been no studies on effect of amber particles on plant cells. The aim of this study was to determine effect of amber nano- and micro- (5 nm-3 μm) particles on somatic and gametic cells and to assess the possibility to use amber particles as alive plant cells markers. To reach the aim, fluorescence of cells was determined in the presence of amber particles, and amber components - spirit of amber and sodium succinate dibasic hexahydrate. Cell fluorescence was measured using a BD FACSJazz® cell sorter for several plants species (Argyranthemum frutescens, Cyclamen persicum, Hordeum vulgare and Linum usitatissimum) with and without treatment of amber. Differences between a control cell group (without amber treatment) and treated cell group with amber particles depended on plant species. The presence of amber components (alcohol soluble amber fraction and sodium succinate) in cultivation media mostly had no influence on cell fluorescence. The study showed that amber particles (size 5 nm-3 μm) can be used as living plant cell markers, as the presence of amber particles in plant cell cultivation media resulted in substantially increased plant cell fluorescence in all investigated species, and there was no detrimental effect of amber particles on plant cells.

Haplotypic variability and population genetic structure of Garganey Anas querquedula and common pochard Aythyla ferina in the Western Palearctic
The mitochondrial DNA (D-loop of mtDNA) sequencing method was used for investigation of various populations of Garganey Anas querquedula and Common Pochard Aythya ferina in the Western Palearctic. Reconstructed phylogenetic relationships based on comparison of D-loop sequences enabled to identify genetic similarity on the level of individual birds and to designate populations with different genetic structure. Identified haplotypic variability indicated the existence of two populations of Garganey with a different genetic structure in Europe. Some genetic variability was also observed among populations of Common Pochard of different origin. Haplotypic variability at different levels was found in both investigated species, despite a considerable overlap in wintering sites used by Garganeys and Common Pochards breeding in various regions.

Abstract
According to the Global Strategy for Plant Conservation, 75% of endangered species should be preserved in ex situ collections till 2020. The genus Liparis has a lot of recognised taxons, but only one species, Liparis loeselii (L.) Rich., grows in Europe. L. loeselii is a rare and endangered orchid species occurring in Europe. In Latvia L. loeselii is classified as the third category of endangered and protected species. To develop the best conservation strategy, the knowledge concerning the genetic differences of protected plants in a particular area is crucial. For this purpose, the genetic diversity of L. loeselii populations from different Latvian habitats was tested. The inter-retrotransposon amplified polymorphism method (iPBS) was used for population genetic diversity evolution. In total, 54 accessions from nine habitats were collected and analysed. L. loeselii leaves have a high content of phenols that reduce the quality of extracted DNA. It was found that the percentage of polymorph loci varied among the populations of L. loeselii growing in different habitats; some of the populations were genetically homogeneous. The genetic diversity levels of L. loeselii populations are related with the population age and the growing conditions.

Abstract
Our goal was to improve the method of obtaining double haploids (DH) by anther culture from Latvian breeding material for several agriculturally important cereals in Latvia: barley, spring and winter wheat. Hybrids from Latvian breeders were initial material. It was found that copper (2.5 mg/l) added to barley anther pre-treatment media and to both barley (C3) and wheat (liquid AMC) induction media, resulted in a higher percentage of green plants-regenerants. In general, the winter wheat hybrids exhibited lower embryogenesis than spring wheat hybrids. Obtaining a large number of DH lines from barley and wheat hybrids with unknown androgenesis response can be organized in two stages: first - selection from breeding initial material hybrids responsive in anther culture, which enables production of green plants-regenerants, and second - production of DH lines in a large scale from selected hybrids.

Abstract
Spring barley breeding has been carried out for almost a century in all three Baltic countries. The efforts of breeders have resulted in many new improved varieties released. The goal of our project was to survey the effect of these efforts throughout the century on this crop. The material included in this study consisted of 64 accessions originating from Latvia, Estonia and Lithuania, representing landraces, varieties released from 1927 to 2001, and breeding lines. Six agronomic traits (days to heading, days to maturing, plant height, harvest index, volumetric weight and thousand kernel weight) were recorded during two years (2002 and 2003) at three locations - Priekuïi (Latvia), Landskrona (Sweden) and Bjørke (Norway). The differences between spring barley materials of different origin and from different breeding periods were assessed, and variation of their performance in different environments was discussed