Molecular cytogenetic analysis of durum wheat × tritordeum hybrids

Genome ◽  
1997 ◽  
Vol 40 (3) ◽  
pp. 362-369 ◽  
Author(s):  
J. Lima-Brito ◽  
H. Guedes-Pinto ◽  
G. E. Harrison ◽  
J. S. Heslop-Harrison

Southern and in situ hybridization were used to examine the chromosome constitution, genomic relationships, repetitive DNA sequences, and nuclear architecture in durum wheat × tritordeum hybrids (2n = 5x = 35), where tritordeum is the fertile amphiploid (2n = 6x = 42) between Hordeum chilense and durum wheat. Using in situ hybridization, H. chilense total genomic DNA hybridized strongly to the H. chilense chromosomes and weakly to the wheat chromosomes, which showed some strongly labelled bands. pHcKB6, a cloned repetitive sequence isolated from H. chilense, enabled the unequivocal identification of each H. chilense chromosome at metaphase. Analysis of chromosome disposition in prophase nuclei, using the same probes, showed that the chromosomes of H. chilense origin were in individual domains with only limited intermixing with chromosomes of wheat origin. Six major sites of 18S–26S rDNA genes were detected on the chromosomes of the hybrids. Hybridization to Southern transfers of restriction enzyme digests using genomic DNA showed some variants of tandem repeats, perhaps owing to methylation. Both techniques gave complementary information, extending that available from phenotypic, chromosome morphology, or isozyme analysis, and perhaps are useful for following chromosomes or chromosome segments during further crossing of the lines in plant breeding programs.Key words: In situ hybridization, molecular cytogenetics, plant breeding, Hordeum chilense, Southern hybridization, durum wheat, hybrids.

1990 ◽  
Vol 95 (3) ◽  
pp. 335-341
Author(s):  
A.R. Leitch ◽  
W. Mosgoller ◽  
T. Schwarzacher ◽  
M.D. Bennett ◽  
J.S. Heslop-Harrison

In situ hybridization using biotinylated total genomic DNA and avidin detection systems was adapted for examination of thin-sectioned plant material in the light and electron microscopes. Root tip material was preserved prior to sectioning, so that the in vivo disposition of the chromatin was maintained. Use of total genomic DNA from Secale africanum as a probe enabled the chromatin from the two parental genomes in the grass hybrid Hordeum chilense × S. africanum to be distinguished. The biotinylated probe preferentially labelled the chromosomes of S. africanum origin. DNA-DNA hybrids were visualized at the light-microscope level by Texas Red fluorescence and at the electron-microscope level by the enzymic precipitation of DAB (diaminobenzidine) or by colloidal gold particles. The use of thin sections allowed the location of probe hybridization to be established unequivocally in both metaphase and interphase nuclei. Analysis of interphase nuclei showed that chromatin originating from the two parental genomes did not intermix but occupied distinct domains.


Genome ◽  
1995 ◽  
Vol 38 (5) ◽  
pp. 946-950 ◽  
Author(s):  
Juan Zhang ◽  
Bernd Friebe ◽  
Bikram S. Gill

Genomic in situ hybridization to somatic metaphase chromosomes of hexaploid wheat cv. Chinese Spring using biotinylated maize genomic DNA as a probe revealed the existence of amplified maize DNA sequences in five pairs of chromosomes. The in situ hybridization sites were located on chromosomes 1A, 7A, 2B, 3B, and 7B. One pair of in situ hybridization sites was also observed in hexaploid oat. The locations and sizes of in situ hybridization sites varied among progenitor species.Key words: Triticum aestivum, Zea mays, shared DNA sequences, genomic in situ hybridization.


Genome ◽  
2006 ◽  
Vol 49 (9) ◽  
pp. 1057-1068 ◽  
Author(s):  
Jiming Jiang ◽  
Bikram S. Gill

Fluorescence in situ hybridization (FISH), which allows direct mapping of DNA sequences on chromosomes, has become the most important technique in plant molecular cytogenetics research. Repetitive DNA sequence can generate unique FISH patterns on individual chromosomes for karyotyping and phylogenetic analysis. FISH on meiotic pachytene chromosomes coupled with digital imaging systems has become an efficient method to develop physical maps in plant species. FISH on extended DNA fibers provides a high-resolution mapping approach to analyze large DNA molecules and to characterize large genomic loci. FISH-based physical mapping provides a valuable complementary approach in genome sequencing and map-based cloning research. We expect that FISH will continue to play an important role in relating DNA sequence information to chromosome biology. FISH coupled with immunoassays will be increasingly used to study features of chromatin at the cytological level that control expression and regulation of genes.


Genome ◽  
1995 ◽  
Vol 38 (6) ◽  
pp. 1163-1169 ◽  
Author(s):  
Qin Chen ◽  
R. L. Conner ◽  
A. Laroche

Labelled total genomic DNA from four alien species, Thinopyrum ponticum (Host) Beauv. (2n = 70, genomes J1J1J1J2J2), Th. bessarabicum (Savul. &Rayss) Love (2n = 14, genome J), Th. elongatum (Host) Beauv. (2n = 14, genome E), and Haynaldia villosa (L.) Schur. (2n = 14, genome V), were used as probes in combination with blocking wheat DNA for in situ hybridization of the chromosomes of Agrotana, a wheat–alien hybrid (2n = 56) of unknown origin. The results showed that genomic DNA probes from Th. ponticum and Th. bessarabicum both clearly revealed 16 alien and 40 wheat chromosomes in Agrotana, indicating that the J genome present in these two species has a high degree of homology with the alien chromosomes in Agrotana. Biotinylated genomic DNA probe from Th. elongatum identified 10 chromosomes from Agrotana, while some regions of six other chromosomes yielded a weak or no signal. The probe from H. villosa produced no differential labelling of the chromosomes of Agrotana. The genomic formula of Agrotana was designated as AABBDDJJ. We suggest that the alien parent donor species of Agrotana is Th. ponticum rather than Th. bessarabicum. Genomic relationships of the three Thinopyrum species are discussed in relation to the distribution of GISH signals in the chromosomes of Agrotana.Key words: Thinopyrum species, wheat–alien amphiploid, genomic DNA probing, in situ hybridization, molecular cytogenetics.


Genome ◽  
1994 ◽  
Vol 37 (5) ◽  
pp. 717-725 ◽  
Author(s):  
Jiming Jiang ◽  
Bikram S. Gill

Nonisotopic in situ hybridization (ISH) was introduced in plants in 1985. Since then the technique has been widely used in various areas of plant genome mapping. ISH has become a routine method for physical mapping of repetitive DNA sequences and multicopy gene families. ISH patterns on somatic metaphase chromosomes using tandemly repeated sequences provide excellent physical markers for chromosome identification. Detection of low or single copy sequences were also reported. Genomic in situ hybridization (GISH) was successfully used to analyze the chromosome structure and evolution of allopolyploid species. GISH also provides a powerful technique for monitoring chromatin introgession during interspecific hybridization. A sequential chromosome banding and ISH technique was developed. The sequential technique is very useful for more precise and efficient mapping as well as cytogenetic determination of genomic affinities of individual chromosomes in allopolyploid species. A critical review is made on the present resolution of the ISH technique and the future outlook of ISH research is discussed.Key words: in situ hybridization, physical mapping, genome mapping, molecular cytogenetics.


1999 ◽  
Vol 112 (23) ◽  
pp. 4397-4404 ◽  
Author(s):  
A. Castilho ◽  
N. Neves ◽  
M. Rufini-Castiglione ◽  
W. Viegas ◽  
J.S. Heslop-Harrison

Triticale (2n=6x=42) is a hybrid plant including rye (R) and wheat (A and B) genomes. Using genomic in situ hybridization with rye DNA as a probe, we found the chromosomes of the R genome were not intermixed with the wheat chromosomes in 85% of nuclei. After treatment of seedlings with low doses of the drug 5-azacytidine (5-AC), leading to hypomethylation of the DNA, the chromosomes became intermixed in 60% of nuclei; the next generation showed intermediate organization. These results correlate with previous data showing that expression of R-genome rRNA genes, normally suppressed, is activated by 5-AC treatment and remains partially activated in the next generation. The distribution of 5-methylcytosine (5-mC) was studied using an antibody to 5-mC. Methylation was detected along the lengths of all chromosomes; there were some chromosome regions with enhanced and reduced methylation, but these were not located at consistent positions, nor were there differences between R and wheat genome chromosomes. After 5-AC treatment, lower levels of methylation were detected. After 5-AC treatment, in situ hybridization with rye genomic DNA sometimes showed micronuclei of rye origin and multiple translocations between wheat and rye chromosomes. Genomic DNA was analysed using methylation-sensitive restriction enzymes and, as probes, two rDNA sequences, two tandemly organised DNA sequences from rye (pSc200 and pSc250), and copia and the gypsy group retrotransposon fragments from rye and wheat. DNA extracted immediately after 5-AC treatment was cut more by methylation-sensitive restriction enzymes than DNA from untreated seedlings. Each probe gave a characteristic restriction fragment pattern, but rye- and wheat-origin probes behaved similarly, indicating that hypomethylation was induced in both genomes. In DNA samples from leaves taken 13–41 days after treatment, RFLP (Restriction Fragment Length Polymorphism) patterns were indistinguishable from controls and 5-AC treatments with all probes. Surprising differences in hybridization patterns were seen between DNA from root tips and leaves with the copia-fragment probes.


Genome ◽  
1995 ◽  
Vol 38 (5) ◽  
pp. 850-857 ◽  
Author(s):  
Esther Ferrer ◽  
Yolanda Loarce ◽  
Gregorio Hueros

Genomic DNA from 19 species and subspecies representing the four basic genomes (H, I, X, and Y) of Hordeum was restricted with HaeIII and hybridized with two repeated DNA sequences of Hordeum chilense. The potential use of repeated sequences in ascertaining genomic affinities within the genus Hordeum was studied by comparing restriction fragment patterns. The study demonstrated the following: (i) species that shared a basic genome showed more similar hybridization fragment patterns than species with different genomes, whether with pHchl or pHch3; (ii) hybridization with pHchl revealed the presence of certain fragments limited to the species with a H genome; and (iii) the alloploid nature of species like H. jubatum was confirmed. The chromosomal distribution of the two repeated sequences was studied in species representing each basic genome and in the amphiploid tritordeum using fluorescent in situ hybridization. No interspecific differences were found between the diploid species. In situ experiments indicated the alloploid nature of H. depressum. Both sequences allow H. chilense chromatin to be distinguished from wheat chromosomes in tritordeum.Key words: repeated DNA sequences; in situ hybridization, Hordeum, tritordeum.


Author(s):  
H. J. Tanke ◽  
J. Vrolijk ◽  
A. K. Raap

In situ hybridization allows the detection of specific nucleic acid sequences in morphologically intact cells and chromosomes. Presently, fluorescence in situ hybridization (FISH) has reached a high detection sensitivity (defined as the smallest DNA target detectable, high DNA resolution (defined as the smallest distance in kilobasepairs between two DNA targets that can be resolved microscopically and a high multiplicity (defined as the number of different probes that can be identified simultaneously. The current status of FISH methodology:*several direct and indirect nucleic acid modifications*sensitivity: unique DNA sequences 1-5 kb*DNA resolution: metaphase ~ > 1-3 Mbp (light microscopy) interphase ~50 kbp DNA halos ~ 1 kbp*multiplicity: at least 12Progress in in situ hybridization and related technology has caused molecular cytogenetics to become an established. In particular the ability of ISH techniques to detect chromosomes and/or chromosome parts in interphase nuclei (interphase cytogenetics) has significantly contributed to this acceptance of ISH, since this technique provides statistically reliable means to study the genetic composition of cells that can not, or only by complicated techniques, be brought in mitosis.


Genome ◽  
2002 ◽  
Vol 45 (2) ◽  
pp. 431-441 ◽  
Author(s):  
Evgueni V Ananiev ◽  
M Isabel Vales ◽  
Ronald L Phillips ◽  
Howard W Rines

DNA gel-blot and in situ hybridization with genome-specific repeated sequences have proven to be valuable tools in analyzing genome structure and relationships in species with complex allopolyploid genomes such as hexaploid oat (Avena sativa L., 2n = 6x = 42; AACCDD genome). In this report, we describe a systematic approach for isolating genome-, chromosome-, and region-specific repeated and low-copy DNA sequences from oat that can presumably be applied to any complex genome species. Genome-specific DNA sequences were first identified in a random set of A. sativa genomic DNA cosmid clones by gel-blot hybridization using labeled genomic DNA from different Avena species. Because no repetitive sequences were identified that could distinguish between the A and D gneomes, sequences specific to these two genomes are refereed to as A/D genome specific. A/D or C genome specific DNA subfragments were used as screening probes to identify additional genome-specific cosmid clones in the A. sativa genomic library. We identified clustered and dispersed repetitive DNA elements for the A/D and C genomes that could be used as cytogenetic markers for discrimination of the various oat chromosomes. Some analyzed cosmids appeared to be composed entirely of genome-specific elements, whereas others represented regions with genome- and non-specific repeated sequences with interspersed low-copy DNA sequences. Thus, genome-specific hybridization analysis of restriction digests of random and selected A. sativa cosmids also provides insight into the sequence organization of the oat genome.Key words: oat, cosmid library, in situ hybridization.


Genome ◽  
2004 ◽  
Vol 47 (5) ◽  
pp. 947-953 ◽  
Author(s):  
G Gonzalez ◽  
V Confalonieri ◽  
C Comas ◽  
C A Naranjo ◽  
L Poggio

The aim of this paper is to test with genomic in situ hybridization the genomic affinities between maize and its putative progenitor Zea mays subsp. parviglumis. Blocking procedures were applied for the purpose of improving discrimination among chromosome regions. Unlabeled genomic DNA from Z. mays subsp. parviglumis as a blocking agent and labeled genomic DNA from maize were hybridized on maize chromosomes. On the other hand, mitotic metaphases from Z. mays subsp. parviglumis were blocked with unlabeled genomic DNA of maize and hybridized with labeled genomic DNA from Z. mays subsp. parviglumis. Both experiments showed that either maize or Z. mays subsp. parviglumis chromosomes have their own unique sequences. This means an unexpected degree of divergence if Z. mays subsp. parviglumis is the only progenitor of maize, a result that is discussed in relation to our previous genomic in situ hybridization observations and to the different scenarios proposed about the origin of maize.Key words: evolutionary relationships, Zea mays subsp. mays, teosinte, Tripsacum, molecular cytogenetics, genomic in situ hybridization (GISH).


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