Cytomolecular identification of individual wheat-wheat chromosome arm associations in wheat-rye hybrids.

Chromosome pairing in the meiotic metaphase I of wheat-rye hybrids has been characterized by sequential genomic and fluorescent in situ hybridization allowing not only the discrimination of wheat and rye chromosomes, but also the identification of the individual wheat and rye chromosome arms involved in the chromosome associations. The majority of associations (93.8%) were observed between the wheat chromosomes. The largest number of wheat-wheat chromosome associations (53%) was detected between the A and D genomes, while the frequency of B-D and A-B associations was significantly lower (32 and 8%, respectively). Among the A-D chromosome associations, pairing between the 3AL and 3DL arms was observed with the highest frequency, while the most frequent of all the chromosome associations (0.113/cell) was found to be the 3DS-3BS. Differences in the pairing frequency of the individual chromosome arms of wheat-rye hybrids have been discussed in relation to the homoeologous relationships between the constituent genomes of hexaploid wheat.

A FISH karyotype to study chromosome polymorphisms for the Elytrigia elongata E genome.

Elytrigia elongata (Host) Nevski(= Agropyron elongatum, Thinopyrum elongatum, 2n = 2x = 14, EE) has long been used as a source of various types of resistance for wheat improvement, and numerous transfers have been made. However, despite heavy use, no high-resolution karyotype exists. We characterized the E. elongata karyotype of several accessions applying highly repetitive DNA sequences as mcFISH probes for chromosome identification. The complete E. elongata disomic chromosome addition series and 11 ditelosomic addition lines in Chinese Spring wheat were exposed to sequential GISH-mcFISH. Based on the mcFISH results, each complete chromosome and each telocentric studied was unambiguously identified. The validation of the karyotype in 4 E. elongata accessions with different geographical origins showed extensive variations in the probe hybridization patterns, but this did not prevent chromosome identification. The established karyotype will be useful for the rapid identification of potential donor chromosomes in wheat improvement programs, allowing appropriate alien transfer.

Characterization of a new 4BS.7HL wheat-barley translocation line using GISH, FISH, and SSR markers and its effect on the ß-glucan content of wheat.

A spontaneous interspecific Robertsonian translocation was revealed by genomic in situ hybridization (GISH) in the progenies of a monosomic 7H addition line originating from a new wheat 'Asakaze komugi' × barley 'Manas' hybrid. Fluorescence in situ hybridization (FISH) with repetitive DNA sequences (Afa family, pSc119.2, and pTa71) allowed identification of all wheat chromosomes, including wheat chromosome arm 4BS involved in the translocation. FISH using barley telomere- and centromere-specific repetitive DNA probes (HvT01 and (AGGGAG)(n)) confirmed that one of the arms of barley chromosome 7H was involved in the translocation. Simple sequence repeat (SSR) markers specific to the long (L) and short (S) arms of barley chromosome 7H identified the translocated chromosome segment as 7HL. Further analysis of the translocation chromosome clarified the physical position of genetically mapped SSRs within 7H, with a special focus on its centromeric region. The presence of the HvCslF6 gene, responsible for (1,3;1,4)-ß-D-glucan production, was revealed in the centromeric region of 7HL. An increased (1,3;1,4)-ß-D-glucan level was also detected in the translocation line, demonstrating that the HvCslF6 gene is of potential relevance for the manipulation of wheat (1,3;1,4)-ß-D-glucan levels.

Identification of new winter wheat - winter barley addition lines (6HS and 7H) using fluorescence in situ hybridization and the stability of the whole 'Martonvásári 9 kr1' - 'Igri' addition set.

A previous paper reported the development of disomic addition lines (2H, 3H, 4H, and 1HS isochromosomic) from hybrids between the winter wheat 'Martonvásári 9 kr1' and the two-rowed winter barley cultivar 'Igri'. The present paper describes the isolation of two new additions, the 7H disomic and 6HS ditelosomic additions, using fluorescence in situ hybridization with the repetitive DNA probes Afa-family and HvT01. The identification of the barley chromosomes in the wheat genome was confirmed with simple sequence repeat markers. The morphological characterization of the new addition lines is also discussed. Studies of the genetic stability of the whole set (2H, 3H, 4H, 7H, 1HS iso, 6HS) of 'Martonvásári 9 kr1' - 'Igri' additions revealed that the most stable disomic additions are 2H and 3H and the most unstable line is the 1HS isochromosomic addition.

Molecular cytogenetic evaluation of chromosome instability in Triticum aestivum-Secale cereale disomic addition lines.

The genetic stability of wheat/rye ('Chinese Spring'/'Imperial') disomic addition lines was checked using the Feulgen method and fluorescent in situ hybridization (FISH). Feulgen staining detected varying proportions of disomic, monosomic, and telosomic plants among the progenies of the disomic addition lines. The greatest stability was observed for the 7R addition line, while the most unstable lines were those with 2R and 4R additions. Chromosome rearrangements were also detected using FISH. Based on the specific hybridization patterns of repetitive DNA probes pSc119.2 and (AAC)(5), as well as ribosomal DNA probes (5S and 45S), isochromosomes were identified in the progenies of 1R and 4R addition lines. The results draw attention to the importance of continuous cytological checks on basic genetic materials by using FISH, because this method reveals chromosome rearrangements that could not be detected either with the conventional Feulgen staining technique or with molecular markers.

Physical mapping of a 7A.7D translocation in the wheat-Thinopyrum ponticum partial amphiploid BE-1 using multicolour genomic in situ hybridization and microsatellite marker analysis.

The absence of chromosome 7D in the wheat-Thinopyrum ponticum partial amphiploid BE-1 was detected previously by multicolour genomic in situ hybridization, sequential FISH (fluorescence in situ hybridization) using repetitive DNA probes, and SSR marker analysis. In the present study the previous cytogenetic and SSR marker analyses were expanded to include 25 other SSR markers assigned to wheat chromosomes 7A and 7D to confirm the presence of a 7A.7D translocation and to specify its composition. An almost complete chromosome 7A and a short chromosome segment derived from the terminal region of 7DL were detected, confirming the presence of a terminal translocation involving the distal regions of 7AL and 7DL. In both cases the position of the translocation breakpoint was different from that of known deletion lines. The identification of the 7AL.7DL translocation and its breakpoint position provides a new physical landmark for future physical mapping studies, opening up the possibility of more precise localization of genes or molecular markers within the terminal regions of 7DL and 7AL.

Mixing of maize and wheat genomic DNA by somatic hybridization in regenerated sterile maize plants.

Intergeneric somatic hybridization was performed between albino maize ( Zea mays L.) protoplasts and mesophyll protoplasts of wheat ( Triticum aestivum L.) by polyethylene glycol (PEG) treatments. None of the parental protoplasts were able to produce green plants without fusion. The maize cells regenerated only rudimentary albino plantlets of limited viability, and the wheat mesophyll protoplasts were unable to divide. PEG-mediated fusion treatments resulted in hybrid cells with mixed cytoplasm. Six months after fusion green embryogenic calli were selected as putative hybrids. The first-regenerates were discovered as aborted embryos. Regeneration of intact, green, maize-like plants needed 6 months of further subcultures on hormone-free medium. These plants were sterile, although had both male and female flowers. The cytological analysis of cells from callus tissues and root tips revealed 56 chromosomes, but intact wheat chromosomes were not observed. Using total DNA from hybrid plants, three RAPD primer combinations produced bands resembling the wheat profile. Genomic in situ hybridization (GISH) using total wheat DNA as a probe revealed the presence of wheat DNA islands in the maize chromosomal background. The increased viability and the restored green color were the most-significant new traits as compared to the original maize parent. Other intermediate morphological traits of plants with hybrid origin were not found.

Analysis of chromosomal polymorphism in barley (Hordeum vulgare L. ssp. vulgare) and between H. vulgare and H. chilense using three-color fluorescence in situ hybridization (FISH).

The aim of the present work was to study chromosomal polymorphism within cultivated barley (Hordeum vulgare ssp. vulgare) using three-color fluorescence in situ hybridization (FISH). The physical distribution of the most frequently used, highly repetitive DNA sequences (GAA)7 specific for pericentromeric heterochromatic regions, the ribosomal DNA clone pTa71, specific for the 45S rDNA, and the barley-specific telomere-associated sequence HvT01, was investigated to reveal genetic diversity in metaphase spreads of ten barley genotypes with diverse geographical origin, growth habit and row number. A wild relative of barley, Hordeum chilense was also studied in order to compare the polymorphism between and within Hordeum species. Significant differences in the hybridization patterns of all three DNA probes could be detected between the two related species, but only probes pTa71 and HvT01 showed variation in the intensity and/or position of hybridization sites among genotypes of H. vulgare ssp. vulgare. The extent of polymorphism was less than that earlier reported for molecular markers and was restricted to the long chromosome arms, with differences between the chromosomes. 1H and 3H proved to be the most variable chromosomes and 4H and 6H the most conserved.

Characterization of a leaf rust-resistant wheat-Thinopyrum ponticum partial amphiploid BE-1, using sequential multicolor GISH and FISH.

In situ hybridization (multicolor GISH and FISH) was used to characterize the genomic composition of the wheat-Thinopyrum ponticum partial amphiploid BE-1. The amphiploid is a high-protein line having resistance to leaf rust (Puccinia recondita f. sp. tritici) and powdery mildew (Blumeria graminis f. sp. tritici) and has in total 56 chromosomes per cell. Multicolor GISH using J, A and D genomic probes showed 16 chromosomes originating from Thinopyrum ponticum and 14 A genome, 14 B genome and 12 D genome chromosomes. Six of the Th. ponticum chromosomes carried segments different from the J genome in their centromeric regions. It was demonstrated that these alien chromosome segments did not originate from the A, B or D genomes of wheat, so the translocation chromosomes were considered to be J(s) type chromosomes carrying segments similar to the S genome near the centromeres. Rearrangements between the A and D genomes of wheat were detected. FISH using Afa family, pSc119.2 and pTa71 probes allowed the identification of all the wheat chromosomes present and the determination of the chromosomes involved in the translocations. The 4A and 7A chromosomes were identified as being involved in intergenomic translocations. The replaced wheat chromosome was identified as 7D. The localization of these repetitive DNA clones on the Th. ponticum chromosomes of the amphiploid was described in the present study. On the basis of their multicolor FISH patterns, the alien chromosomes could be arranged in eight pairs and could also be differentiated unequivocally from each other.

Development and molecular cytogenetic identification of new winter wheat--winter barley ('Martonvásári 9 kr1' - 'Igri') disomic addition lines.

This paper describes a series of winter wheat - winter barley disomic addition lines developed from hybrids between winter wheat line Triticum aestivum L. 'Martonvásári 9 kr1' and the German 2-rowed winter barley cultivar Hordeum vulgare L. 'Igri'. The barley chromosomes in a wheat background were identified from the fluorescent in situ hybridization (FISH) patterns obtained with various combinations of repetitive DNA probes: GAA-HvT01 and pTa71-HvT01. The disomic addition lines 2H, 3H, and 4H and the 1HS isochromosome were identified on the basis of a 2-colour FISH with the DNA probe pairs GAA-pAs1, GAA-HvT01, and pTa71-HvT01. Genomic in situ hybridization was used to confirm the presence of the barley chromosomes in the wheat genome. The identification of the barley chromosomes in the addition lines was further confirmed with simple-sequence repeat markers. The addition lines were also characterized morphologically.

Production and meiotic pairing behaviour of new hybrids of winter wheat (Triticum aestivum) x winter barley (Hordeum vulgare).

New winter wheat (Triticum aestivum L.) x winter barley (Hordeum vulgare L.) hybrids produced using cultivated varieties (wheat 'Martonvásári 9 krl'(Mv9 krl) x barley 'Igri', Mv9 krl x 'Osnova', 'Asakazekomugi' x 'Manas') were multiplied in tissue culture because of the high degree of sterility and then pollinated with wheat to obtain backcross progenies. Meiotic analysis of the hybrids Mv9 krl x 'Igri' and 'Asakazekomugi' x 'Manas' and their in vitro regenerated progenies with the Feulgen method revealed 1.59 chromosome arm associations per cell in both initial hybrids. The number of chromosome arm associations increased after in vitro culture to 4.72 and 2.67, respectively, in the two combinations. According to the genomic in situ hybridization (GISH) analysis, wheat-barley chromosome arm associations made up 3.6% of the total in the initial Mv9 krl x 'Igri' hybrid and 6.6% and 16.5% of the total in in vitro regenerated progenies of the 'Asakazekomugi' x 'Manas' and Mv9 krl x 'Igri' hybrids, respectively. The demonstration by GISH of wheat-barley chromosome pairing in the hybrids and especially in their in vitro regenerated progenies proves the possibility of producing recombinants between these two genera, and thus of transferring useful characters from barley into wheat. In vitro conditions caused an increase in chromosome arm association frequency in both combinations and in fertility in some regenerants.

Identification of wheat-barley translocations by sequential GISH and two-colour FISH in combination with the use of genetically mapped barley SSR markers.

Five wheat-barley translocations in a wheat background were characterized through the combination of cytogenetic and molecular genetic approaches. The wheat chromosome segments involved in the translocations were identified using sequential GISH and two-colour FISH with the probes pSc119.2 and pAs1. The barley chromatin in these lines was identified using SSR markers. A total of 45 markers distributed over the total barley genome were selected from a recently published linkage map of barley and tested on the translocation lines. The following translocations were identified: 2DS.2DL-1HS, 3HS.3BL, 6BS.6BL-4HL, 4D-5HS, and 7DL.7DS-5HS. Wheat-barley disomic and ditelosomic addition lines for the chromosomes 3HS, 4H, 4HL, 5H, 5HL, and 6HS were used to determine the correct location of 21 markers and the position of the centromere. An intragenomic translocation breakpoint was detected on the short arm of the barley chromosome 5H with the help of SSR marker analysis. Physical mapping of the SSR markers on chromosomes 1H and 5H was carried out using the intragenomic and the interspecific translocation breakpoints, as well as the centromere, as physical landmarks.

Analysis and sorting of rye (Secale cereale L.) chromosomes using flow cytometry.

Procedures for chromosome analysis and sorting using flow cytometry (flow cytogenetics) were developed for rye (Secale cereale L.). Suspensions of intact chromosomes were prepared by mechanical homogenization of synchronized root tips after mild fixation with formaldehyde. Histograms of relative fluorescence intensity obtained after the analysis of DAPI-stained chromosomes (flow karyotypes) were characterized and the chromosome content of the DNA peaks was determined. Chromosome 1R could be discriminated on a flow karyotype of S. cereale 'Imperial'. The remaining rye chromosomes (2R-7R) could be discriminated and sorted from individual wheat-rye addition lines. The analysis of lines with reconstructed karyotypes demonstrated a possibility of sorting translocation chromosomes. Supernumerary B chromosomes could be sorted from an experimental rye population and from S. cereale 'Adams'. Flow-sorted chromosomes were identified by fluorescence in situ hybridization (FISH) with probes for various DNA repeats. Large numbers of chromosomes of a single type sorted onto microscopic slides facilitated detection of rarely occurring chromosome variants by FISH with specific probes. PCR with chromosome-specific primers confirmed the identity of sorted fractions and indicated suitability of sorted chromosomes for physical mapping. The possibility to sort large numbers of chromosomes opens a way for the construction of large-insert chromosome-specific DNA libraries in rye.

Molecular cytogenetic analysis of Aegilops cylindrica host.

The genomic constitution of Aegilops cylindrica Host (2n = 4x = 28, DcDcCcCc) was analyzed by C-banding, genomic in situ hybridization (GISH), and fluorescence in situ hybridization (FISH) using the DNA clones pSc119, pAs1, pTa71, and pTA794. The C-banding patterns of the Dc- and Cc-genome chromosomes of Ae. cylindrica are similar to those of D-and C-genome chromosomes of the diploid progenitor species Ae. tauschii Coss. and Ae. caudata L., respectively. These similarities permitted the genome allocation and identification of the homoeologous relationships of the Ae. cylindrica chromosomes. FISH analysis detected one major 18S-5.8S-25S rDNA locus in the short arm of chromosome 1Cc. Minor 18S-5.8S-25S rDNA loci were mapped in the short arms of 5Dc and 5Cc. 5S rDNA loci were identified in the short arm of chromosomes 1Cc, 5Dc, 5Cc, and 1Dc. GISH analysis detected intergenomic translocation in three of the five Ae. cylindrica accessions. The breakpoints in all translocations were non-centromeric with similar-sized segment exchanges.