[Mapping of meiotic genes in rye (Secale cereale L.): localization of sy19 mutation, impairing homologous synapsis, by means of isozyme and microsatellite markers].

The sy19 mutation, which impairs the homology of meiotic chromosome synapsis in rye, were mapped using a specially created F2 population by means of isozyme Acph 1 locus and microsatellite (SSR) markers. The sy19gene was localized in the chromosome 7R in the pericentromeric region of long armbased on the linked inheritance with the Acph 1 locus. The locus was linked with five rye SSR markers, with the Xrems 1234 locus being located closest to the sy19 gene (6.4 cM). The genetic map of the analyzed chromosome 7R region includes ten markers and the sy19 locus. A possible function of the Sy1 and Sy19 genes based on the data on comparative genomics is discussed.

[Mapping of meiotic genes in rye (Secale cereale L.): localization of sy18 mutation with impaired homologous synapsis using microsatellite markers].

The recessive spontaneous sy18 mutation with nonhomologous synapsis was mapped in rye. The sy18 gene was located in the centromeric region of chromosome 2R in relation to three rye SSR (simple sequence repeats) loci, i.e., Xrems1130, Xrems1203, and Xscm43, and one wheat SSR locus Xgwm132. The desynaptic sy18 gene is located in the interval between Xrems1130 and Xrems1203 markers at a distance of 0.5 cM and 3.1 cM, respectively. The possible evolutionary relationships of the mapped gene with homologous loci of the related species are discussed.

[Genetic polymorphism of flax Linum usitatissimum based on use of molecular cytogenetic markers].

Using a set of approaches based on the use of molecular cytogenetic markers (DAPI/C-banding, estimation of the total area of DAPI-positive regions in prophase nuclei, FISH with 26S and 5S rDNA probes) and the microsatellite (SSR-PCR) assay, we studied genomic polymorphism in 15 flax (Linum usitatissimum L.) varieties from different geographic regions belonging to three directions of selection (oil, fiber, and intermediate flaxes) and in the k-37 x Viking hybrid. All individual chromosomes have been identified in the karyotypes of these varieties on the basis of the patterns of differential DAPI/C-banding and the distribution of 26S and 5S rDNA, and idiograms of the chromosomes have been generated. Unlike the oil flax varieties, the chromosomes in the karyotypes of the fiber flax varieties have, as a rule, pericentromeric and telomeric DAPI-positive bands of smaller size, but contain larger intercalary regions. Two chromosomal rearrangements (chromosome 3 inversions) were discovered in the variety Luna and in the k-37 x Viking hybrid. In both these forms, no colocalization of 26S rDNA and 5S rDNA on the satellite chromosome was detected. The SSR assay with the use of 20 polymorphic pairs of primers revealed 22 polymorphic loci. Based on the SSR data, we analyzed genetic similarity of the flax forms studied and constructed a genetic similarity dendrogram. The genotypes studied here form three clusters. The oil varieties comprise an independent cluster. The genetically related fiber flax varieties Vita and Luna, as well as the landrace Lipinska XIII belonging to the intermediate type, proved to be closer to the oil varieties than the remaining fiber flax varieties. The results of the molecular chromosomal analysis in the fiber and oil flaxes confirm their very close genetic similarity. In spite of this, the combined use of the chromosomal and molecular markers has opened up unique possibilities for describing the genotypes of flax varieties and creating their genetic passports.

[Molecular genetic mapping of the sy1 and sy9 asynaptic genes in rye (Secale cereale L.) using microsatellite and isozyme markers].

Studies of phenotypical expression of synaptic mutations in combination with the localization of corresponding genes on a genetic map permit individual stages of the meiotic process to be differentiated. Two rye asynaptic genes, sy1 and sy9, were mapped with the use of microsatellite markers (SSR) in the pericentromeric regions of the long chromosome arms 7R and 2R, respectively. The sy9 gene cosegregated with two SSR markers Xscm43 and Xgwm132. The asynaptic gene sy1 was mapped within the interval between the isozyme locus Aat2 and two cosegregating loci Xrems1188 and Xrems1135 that are located at a distance of 0.4 cM proximally and 0.1 cM distally with respect to the gene lous. Possible evolutionary relationships of the mapped genes with homeological loci of the Triticeae species and more distant cereal species, such as maize and rice, are discussed.

[Identification of leaf rust resistance genes in wheat (Triticum aestivum L.) cultivars using molecular markers].

A collection of 68 cultivars of common wheat has been screened for leaf rust resistance genes with the use of molecular markers. Markers of genes Lr1, Lr9, Lr10, Lr19, Lr20, Lr21, Lr24, and Lr26 have been used. It has been suggested that allele Xgwm295 be used as a marker for identifying the Lr34 gene. The genes originating from Triticum aestivum L., as well as the Lr26 gene contained in rye translocation 1RS, are the most frequent. Genes originating from wild wheats were rarer in the cultivars studied.

Genetic and physical mapping of homoeologous recombination points involving wheat chromosome 2B and rye chromosome 2R.

Wide hybrids have been used in generating genetic maps of many plant species. In this study, genetic and physical mapping was performed on ph1b-induced recombinants of rye chromosome 2R in wheat (Triticum aestivum L.). All recombinants were single breakpoint translocations. Recombination 2RS-2BS was absent from the terminal and the pericentric regions and was distributed randomly along an intercalary segment covering approximately 65% of the arm's length. Such a distribution probably resulted from structural differences at the telomeres of 2RS and wheat 2BS arm that disrupted telomeric initiation of pairing. Recombination 2RL-2BL was confined to the terminal 25% of the arm's length. A genetic map of homoeologous recombination 2R-2B was generated using relative recombination frequencies and aligned with maps of chromosomes 2B and 2R based on homologous recombination. The alignment of the short arms showed a shift of homoeologous recombination toward the centromere. On the long arms, the distribution of homoeologous recombination was the same as that of homologous recombination in the distal halves of the maps, but the absence of multiple crossovers in homoeologous recombination eliminated the proximal half of the map. The results confirm that homoeologous recombination in wheat is based on single exchanges per arm, indicate that the distribution of these single homoeologous exchanges is similar to the distribution of the first (distal) crossovers in homologues, and suggest that successive crossovers in an arm generate specific portions of genetic maps. A difference in the distribution of recombination between the short and long arms indicates that the distal crossover localization in wheat is not dictated by a restricted distribution of DNA sequences capable of recombination but by the pattern of pairing initiation, and that can be affected by structural differences. Restriction of homoeologous recombination to single crossovers in the distal part of the genetic map complicates chromosome engineering efforts targeting genes in the proximal map regions.

[Comparative molecular-genetic mapping of genomes of rye (Secale cereale L.) and other cereals]. / Sravnitel'noe molekuliarno-geneticheskoe kartirovanie genoma rzhi (Secale cereale L.) i drugikh zlakov.

The genetic map of rye consisting of 149 RFLP, 20 isozyme and 12 microsatellite markers was developed. Using the collection of cross-hybridizing probes, the presence of multiple translocations in rye genome with respect to wheat and barley genomes was shown. However, within large regions of genome a strict collinearity of marker order was observed that allow us to use the method of comparative mapping for an introduction of new genes. In the developed genetic map 18 morphological and breeding-valuable genes mapped in different rye populations were integrated. The comparative analysis of homeological loci in genomes of Triticeae species as well as in genomes of rice and maize was carried out. The genes controlling a number of morphological traits, plant height, photoperiodic response and winter/spring growth habit were shown to be conserve among cereals and to form clear homoeologous rows.

[The molecular genetic mapping of cereal crops]. / Molekuliarno-geneticheskoe kartirovanie zlakovykh kul'tur.

The application of modern methods of genetic mapping using RFLP and PCR technologies allowed to advance essentially in construction of rye genome genetic maps and mapping of some morphological and breeding-valuable genes. Genetic mapping of cereal genomes, such as rye, wheat, maize and rice using common set of DNA-probes permitted to reveal considerable evolutionary conservation in gene organization and localization. This allows to use more effectively method of comparative mapping for fast localization and tagging of genes in genomes of less investigated species.

Radioactive contamination in the environment of the nuclear enterprise 'Mayak' PA. Results from the joint Russian-Norwegian field work in 1994.

A brief overview of the radioactive waste inventory of the 'Mayak' PA reprocessing plant, Chelyabinsk Region, Russia is given together with a description of the environmental contamination caused by its activities and the origins of contamination. The joint Russian-Norwegian field work in 1994 is described, together with the major analytical results. The field work was of a limited extent, and was not designed to include a complete mapping of the environmental contamination around the plant. The results are, however, in good agreement with the very extensive previous Russian investigations. The highest concentrations of radioactivity were found in Reservoirs 10 and 11 and at the floodplain of the upper Techa River (Asanov Swamp). Also high concentrations are found in biota, especially fish from Reservoir 10.