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Wheat-rye translocations involving 1RS and 2RL of rye are the most useful sources of genes for disease resistance in wheat breeding. Rye genes are known to control resistance to biotic and abiotic stresses. Wheat-rye translocations have been widely used by breeders all over the world because genes located on translocated chromosome arms or fragments from the rye genome can determine a number of useful traits in wheat, such as high yield, wide adaptation, diseases and pest resistance. The wheat-rye translocation lines used in this study were derived from a cross between the Swedish bread wheat variety Topper and the line KR99-139 being homozygous for the two different wheat-rye translocations 1BL/1RS and 2RL/2BS. BC1F1 materials were obtained through one back-cross with either the line KR99-139 or the variety Topper. Thereafter, BC1F2 and BC1F3 were obtained by once and twice selfing. In the obtained material, it was thereafter possible to define four different possible homozygous translocation combinations. Thus, lines containing both 1RS and 2RL translocations, containing only 1RS or 2RL and without any translocation were identified. For identification of the four possible homozygous wheat-rye translocation lines mentioned above, three different methods were used. First, lines of different types were characterized and isolated based on a phenotypical marker, i.e. if the plant showed red or green coleoptile colour. Plants with homozygous presence of 2RL were known to develop red coleoptile, as a gene for red coleoptile has been verified to be present at 2RL in these lines. The analyses of coleoptile colours were done in the BC1F2 (obtained from selfed BC1F1 lines determined by molecular markers at BAZ, Germany to be 1RS– –/2RL+–) and BC1F3 (obtained from the BC1F2 lines having a red coleoptile) wheat-rye translocation lines, where the variety Topper had been used for backcrossing. Moreover, the BC1F2 (obtained from selfed BC1F1 lines determined by molecular markers

Tetraploid Bromus ciliatus L. is a North American bromegrass that has been placed in the Pnigma section of Bromus. The objective of this study was to characterize the genome of tetraploid B. ciliatus by cytogenetic methods and compare it to the genomes of other species included in the section Pnigma. All the plants of the accession (USDA PI 232214) selected for chromosome counting were tetraploids (2n = 28). The mean 2C nuclear DNA content for tetraploid B. ciliatus was 19.13 ± 0.07 pg as determined by flow cytometry which is significantly greater than the tetraploid DNA content of B. inermis Leyss. (11.74 ± 0.16 pg). C-banding procedures were used to identify individual mitotic chromosomes and to develop a karyotype for B. ciliatus. The genome of the tetraploid B. ciliatus consisted of 16 median chromosomes, eight submedian chromosomes, and four chromosomes with satellites which included one pair with a large satellite and one pair with a small satellite. The general pattern of the distribution of constitutive heterochromatin in B. ciliatus was quite different than the other bromegrasses that have been analyzed to date. Except for two pairs of chromosomes, all chromosomes in tetraploid B. ciliatus had telomeric bands on one or both arms. Some of the chromosomes with telomeric bands had centromeric bands that were located at one or both sides of the centromere and intercalary bands which were generally absent in the other bromegrass species. It was possible to identify all chromosomes of tetraploid B. ciliatus and to match the pairs of homologous chromosomes by using chromosome lengths, arm length ratios and C-banding patterns. The results of this study indicate that tetraploid B. ciliatus has different genomes than the European species evaluated to date in the section Pnigma.

The aim of this study was to describe mitotic and meiotic chromosomes of Cycloneda sanguinea using C-banding, flourescent in situ hybridization (FISH) rDNA probes, and sequential FISH/Ag-NOR staining. The chromosome number was 2n = 18 + XX for females and 2n = 18 + Xy for males. The X chromosome was metacentric and the Y chromosome was very small. During meiosis, the karyotypic meioformula was n = 9 + Xyp, and sex chromosomes configured a parachute at metaphase I. At the beginning of pachytene, bivalents were still individualized, and sex chromosomes were associated end-to-end through the heteropycnotic region of the X chromosome. Later in pachytene, further condensation led to the formation of a pseudo-ring by the sex bivalent. All chromosomes showed pericentromeric heterochromatin. FISH and sequential FISH/Ag-NOR staining evidenced the location of the nucleolar organizer region in one pair of autosomes (at spermatogonial metaphase). During meiosis, these genes were mapped to a region outside the sex vesicle by FISH, although Xyp was deeply stained with silver at metaphase I. These results suggest that these argyrophilic substances are of a nucleolar protein nature, and seem to be synthesized by a pair of autosomes and imported during meiosis (prophase I) to the sex pair, during the association of the sex chromosomes. Copyright by the Brazilian Society of Genetics.

The aim of this study was to describe mitotic and meiotic chromosomes of Cycloneda sanguinea using C-banding, flourescent in situ hybridization (FISH) rDNA probes, and sequential FISH/Ag-NOR staining. The chromosome number was 2n = 18 + XX for females and 2n = 18 + Xy for males. The X chromosome was metacentric and the Y chromosome was very small. During meiosis, the karyotypic meioformula was n = 9 + Xyp, and sex chromosomes configured a parachute at metaphase I. At the beginning of pachytene, bivalents were still individualized, and sex chromosomes were associated end-to-end through the heteropycnotic region of the X chromosome. Later in pachytene, further condensation led to the formation of a pseudo-ring by the sex bivalent. All chromosomes showed pericentromeric heterochromatin. FISH and sequential FISH/Ag-NOR staining evidenced the location of the nucleolar organizer region in one pair of autosomes (at spermatogonial metaphase). During meiosis, these genes were mapped to a region outside the sex vesicle by FISH, although Xyp was deeply stained with silver at metaphase I. These results suggest that these argyrophilic substances are of a nucleolar protein nature, and seem to be synthesized by a pair of autosomes and imported during meiosis (prophase I) to the sex pair, during the association of the sex chromosomes. Copyright by the Brazilian Society of Genetics.

Chromosomes of the short-tailed shrew Blarina brevicauda, which display the numerical polymorphism arisen from Robertsonian rearrangements, were analyzed with conventional and silver staining and G- and C-banding techniques. With respect to all specimens examined in the present study, the diploid chromosome number (2n) and fundamental autosomal arm number (FN) were 50 and 48, respectively. The karyotype consisted of 24 pairs of acrocentric autosomes, a large-sized metacentric X chromosome, and a small-sized submetacentric Y chromosome. The comparison with previous findings suggested the geographic polymorphism of Y chromosome in this species. All autosomes and the X chromosome carried slight centromeric constitutive heterochromatin, whereas the Y chromosome was entirely heterochromatic. On the satellites of short arms of two autosomal pairs, the nucleolus organizer regions (NORs) were recognized. The G- and C-banded and Ag-NOR-stained karyotypes presented in the present study could be useful cytogenetic characteristics for specification of chromosomes participating in Robertsonian rearrangements within this species and for karyo-systematic study of genus Blarina.

Chromosomes of the short-tailed shrew Blarina brevicauda, which display the numerical polymorphism arisen from Robertsonian rearrangements, were analyzed with conventional and silver staining and G- and C-banding techniques. With respect to all specimens examined in the present study, the diploid chromosome number (2n) and fundamental autosomal arm number (FN) were 50 and 48, respectively. The karyotype consisted of 24 pairs of acrocentric autosomes, a large-sized metacentric X chromosome, and a small-sized submetacentric Y chromosome. The comparison with previous findings suggested the geographic polymorphism of Y chromosome in this species. All autosomes and the X chromosome carried slight centromeric constitutive heterochromatin, whereas the Y chromosome was entirely heterochromatic. On the satellites of short arms of two autosomal pairs, the nucleolus organizer regions (NORs) were recognized. The G- and C-banded and Ag-NOR-stained karyotypes presented in the present study could be useful cytogenetic characteristics for specification of chromosomes participating in Robertsonian rearrangements within this species and for karyo-systematic study of genus Blarina.

Four minor rDNA loci have been mapped physically to barley (Hordeum vulgare L.) chromosomes 1 (7I), 2 (2I), 4 (4I), and 5 (1I) by a two-step in situ hybridization procedure including a GAA microsatellite sequence. Reprobing with the microsatellite resulted in a distinct banding pattern, resembling the C-banding pattern, which enabled unequivocal chromosome identification. This study suggests that gene mapping accuracy may be improved by using probes with well-characterized and narrow hybridization sites as cytological markers which are situated close to the gene locus. One of the rDNA loci is located about 54% out on the short arm of chromosome 4 and it has not previously been reported in barley. We have disignated the new locus Nor-16. rDNA loci on homoeologous group 4 chromosomes have not yet been reported in other Triticeae species. The origin of these 4 minor rDNA loci is discussed in relation to their equilocal distribution on the chromosomes.

Four minor rDNA loci have been mapped physically to barley (Hordeum vulgare L.) chromosomes 1 (7I), 2 (2I), 4 (4I), and 5 (1I) by a two-step in situ hybridization procedure including a GAA microsatellite sequence. Reprobing with the microsatellite resulted in a distinct banding pattern, resembling the C-banding pattern, which enabled unequivocal chromosome identification. This study suggests that gene mapping accuracy may be improved by using probes with well-characterized and narrow hybridization sites as cytological markers which are situated close to the gene locus. One of the rDNA loci is located about 54% out on the short arm of chromosome 4 and it has not previously been reported in barley. We have disignated the new locus Nor-16. rDNA loci on homoeologous group 4 chromosomes have not yet been reported in other Triticeae species. The origin of these 4 minor rDNA loci is discussed in relation to their equilocal distribution on the chromosomes.

Four minor rDNA loci have been mapped physically to barley (Hordeum vulgare L.) chromosomes 1 (7I), 2 (2I), 4 (4I), and 5 (1I) by a two-step in situ hybridization procedure including a GAA microsatellite sequence. Reprobing with the microsatellite resulted in a distinct banding pattern, resembling the C-banding pattern, which enabled unequivocal chromosome identification. This study suggests that gene mapping accuracy may be improved by using probes with well-characterized and narrow hybridization sites as cytological markers which are situated close to the gene locus. One of the rDNA loci is located about 54% out on the short arm of chromosome 4 and it has not previously been reported in barley. We have disignated the new locus Nor-16. rDNA loci on homoeologous group 4 chromosomes have not yet been reported in other Triticeae species. The origin of these 4 minor rDNA loci is discussed in relation to their equilocal distribution on the chromosomes.

[EN] The chromosome constitution and alterations and the meiotic behaviour in 35 plants of the F3, F4, and F6 progenies of hybrids between 6x-triticale (female) and Triticum aestivum L. (male) were analyzed. The C-banding pattern of twelve wheat meiotic chromosomes (2A, 4A, 5A, 7A, the seven of the B genome and one characterized but no identified pair) and seven of rye permitted their unequivocal recognition at first metaphase cells. Moreover, A and D chromosomes were genomically distinguished because of their morphological differences. C-banding in meiosis proved to be a good method to score the individual levels of pairing, to verify the chromosome constitution, and to detect structural variations and modifications. Among 35 plants examined at meiosis, the chromosome constitution varied in third genome (0-7 D and 8-13 R) having in common the A and B chromosome pairs. Rye chromosomes 3R, 4R, 5R, 6R and 7R were foun as more or less modified chromosomes in some plants. The modifications consisted in either a reduction or loss of both terminal and intercalary heterochromatin. Neither the balance between D an R chromosomes no the number of R chromosomes in the third genome seems to be an important factor affecting pairing levels in the segregant plants. [ES] Se estudian la contitución cromosómica y alteraciones y el comportamiento meiótico de 35 plantas de las generaciones F3, F4 y F6 procedentes de un híbrido entre Triticale-x6 (hembra) y Triticum aestivum L. (polen). El patrón de bandas-C de 12 cromosomas meióticos de trigo (2A, 4A, 5A, 7A, los siete del genomio B y uno caracterizado aunque no identificado) y los siete del centeno permitó su reconocimiento en células en primera metafase. Además, los cromosomas de los genomios A y D fueron reconocidos debido a sus diferentes morfologías. El bandeo C en meiosis resultó ser una buena técnica para el análisis de los niveles individuales de apareamiento, verificar la constitución cromosómica, y detectar variaciones estruc