A rapid technique for substituting alien chromosomes into Triticum aestivum and determining their homoeology

1985 ◽  
Vol 27 (5) ◽  
pp. 549-558 ◽  
Author(s):  
Rama S. Kota ◽  
Jan Dvořák

A rapid technique is described for the production of a disomic substitution of an alien chromosome for a selected wheat chromosome directly from the amphiploid. Determination of homoeology between the chromosomes involved is a by-product of this technique. The technique involves the production of a nullisomic amphiploid from a cross between a wheat mono-telosomic and a diploid species and recurrently backcrossing it as a male twice to the monotelosomic. Disomic and ditelosomic substitutions are then selected upon self-pollination. The utility of this technique is shown by producing a large number of disomic and ditelosomic substitutions of an Aegilops longissima chromosome homoeologous to wheat chromosome 6B from two populations of Ae. longissima. The incorporated Ae. longissima chromosome was characterized by C-banding and in situ hybridization of an 18S–26S rRNA gene probe. The chromosome differs in C-band pattern from chromosome 6B of 'Chinese Spring' and does not pair with the 6Bp telosome at metaphase I. It also differs from 'Chinese Spring' chromosome 6B by having the 18S–26S rRNA compound locus in the long arm.Key words: disomic substitution, homoeology, C-banding, in-situ hybridization, rRNA genes, gene synteny, Triticum, Aegilops longissima.

Genome ◽  
1992 ◽  
Vol 35 (6) ◽  
pp. 1013-1018 ◽  
Author(s):  
I. J. Leitch ◽  
J. S. Heslop-Harrison

The 18S–5.8S–26S rRNA genes have been located on five pairs of barley (Hordeum vulgare L., 2n = 2x = 14) chromosomes (in descending order of copy number, barley chromosome numbers 6, 7, 5, 1, and 2; homoeologous groups 6I, 5I, 1I, 7I, and 2I) by in situ hybridization followed by C-banding. All sites were at intercalary positions. The pairs of major sites on chromosomes 6 (6I)1 and 7 (5I) are well known. Silver staining of nuclei and meiotic analysis have previously indicated that additional rDNA sites may be present, but the presence of sites on a further three chromosome pairs was unexpected. Within the tribe Triticeae, few species have more than two pairs of rDNA sites, and they have not been reported on group 2 chromosomes. We propose calling the new sites Nor-I1 (on chromosome 5 (1I)), Nor-I4 (on chromosome 1 (7I)), and Nor-I5 (on chromosome 2 (2I)), and that any further rDNA sites on homoeologous group 2 chromosomes should be called Nor-5. As conventional, all designations are based on temporal order of discovery in the Triticeae and designating the H. vulgare genome as I. In situ hybridization is valuable for gene mapping, since it can detect the presence of genes with a very wide range of copy numbers at different sites.Key words: C-banding, nucleolus organizer regions, fluorescent in situ hybridization, Hordeum vulgare, gene mapping.


Genome ◽  
1997 ◽  
Vol 40 (5) ◽  
pp. 689-696 ◽  
Author(s):  
A Fominaya ◽  
S. Molnar ◽  
G. Fedak ◽  
K. C. Armstrong ◽  
N.-S. Kim ◽  
...  

Diagnostic markers for eight Thinopyrum distichum addition chromosomes in Triticum turgidum were established using C-banding, in situ hybridization, and restriction fragment length polymorphism analysis. The C-band karyotype conclusively identified individual Th. distichum chromosomes and distinguished them from chromosomes of T. turgidum. Also, TaqI and BamHI restriction fragments containing 5S and 18S–5.8S–26S rRNA sequences were identified as positive markers specific to Th. distichum chromosomes. Simultaneous fluorescence in situ hybridization showed both 5S and 18S–5.8S–26S ribosomal RNA genes to be located on chromosome IV. Thinopyrum distichum chromosome VII carried only a 18S–5.8S–26S rRNA locus and chromosome pair II carried only a 5S rRNA locus. The arrangement of these loci on Th. distichum chromosome IV was different from that on wheat chromosome pair 1B. Two other unidentified Th. distichum chromosome pairs also carried 5S rRNA loci. The homoeologous relationship between Th. distichum chromosomes IV and VII and chromosomes of other members of the Triticeae was discussed by comparing results obtained using these physical and molecular markers.Key words: Triticum turgidum, homoeologous relationship, Triticeae, addition lines, NOR.


Genome ◽  
1996 ◽  
Vol 39 (1) ◽  
pp. 56-62 ◽  
Author(s):  
Xiwen Cai ◽  
Stephen S. Jones ◽  
Timothy D. Murray

Related wheat (Triticum aestivum L.) breeding lines, PI 561033, REA 9232, REA 9257, and CI 13113 were analyzed cytogenetically to characterize the association of resistance to cephalosporium stripe (caused by Cephalosporium gramineum Nis. & Ika.) with Agropyron elongatum chromatin. One pair of A. elongatum chromosomes was detected in PI 561033, REA 9232, and CI 13113 by genomic in situ hybridization. The sib line of PI 561033 and REA 9232, REA 9257, which is not resistant to this disease, lacked this pair of A. elongatum chromosomes. PI 561033 was characterized as a disomic T. aestivum – A. elongatum 6Ae#2(6A) chromosome substitution line using test crosses and C-banding. In situ hybridization and test crosses showed that the donor parent, CI 13113, also had chromosome 6A substituted by A. elongatum chromosome 6Ae#2. The C-banding pattern of 6Ae#2 showed two subterminal bands on the long arm and one small band proximal to the centromere on the short arm. Based on chromosome pairing and compensation, chromosome 6Ae#2 shows a close homoeologous relationship with wheat chromosome 6A. Key words : Cephalosporium gramineum, Agropyron elongatum, in situ hybridization, C-banding, chromosome substitution.


Genome ◽  
1996 ◽  
Vol 39 (2) ◽  
pp. 258-265 ◽  
Author(s):  
I. Galasso ◽  
D. Pignone ◽  
M. Frediani ◽  
M. Maggiani ◽  
R. Cremonini

The karyotypes of three accessions, one each from three annual species of the genus Cicer, namely Cicer arietinum, Cicer reticulation, and Cicer echinospermum, were examined and compared using C-banding, the fluorochromes chromomycin A3, DAPI, and Hoechst 33258, in situ hybridization of the 18S–5.8S–25S and 5S rDNA sequences, and silver staining. The nuclear DNA content of the three species and the amount of heterochromatin were also determined. The results suggest an evolutionary pathway in which C. reticulatum is the ancestral species from which both C. arietinum and C. echinospermum are derived with the loss of one pair of satellites; subsequently, C. echinospermum further differentiated by the accumulation of chromosomal rearrangement(s) that gave rise to a hybrid sterility barrier. Key words : Cicer, C-banding, fluorochromes, Ag staining, rRNA genes.


1999 ◽  
Vol 77 (3) ◽  
pp. 389-393 ◽  
Author(s):  
Jin-Feng Chen ◽  
Jack E Staub ◽  
Jeffrey W Adelberg ◽  
Jiming Jiang

The chromosomal locations of the genes coding for the 18S-5.8S-26S rRNA was investigated in Cucumis species using fluorescence in situ hybridization. Cucumber (Cucumis sativus L., 2n = 2x = 14) possesses four pairs of rDNA loci that were mapped to chromosomes 1C, 2C, 4C, and 7C. The distinctive hybridization sites of the 18S-5.8S-26S rRNA genes provide several useful cytogenetic markers for identification of chromosomes in C. sativus. The 18S-5.8S-26S rDNA genes have also been detected on two chromosome pairs, one major and one minor pair of loci, in melon (Cucumis melo L., 2n = 2x = 24) and on three pairs of Cucumis hystrix Chakr. chromosomes. The different number and pattern of rDNA sites is consistent with the hypothesis that considerable phylogenetic distance exists among these species.Key words: fluorescence in situ hybridization, 45S rRNA gene, cytogenetics, Cucumis sativus, Cucucmis melo, Cucumis hystrix.


1986 ◽  
Vol 28 (2) ◽  
pp. 266-271 ◽  
Author(s):  
Rama S. Kota ◽  
Jan Dvořák

A deletion in the p arm of chromosome 5B of Triticum aestivum L. cv. Chinese Spring was identified by C-banding during the production of disomic substitutions of 6B of Aegilops longissima Schweinf. et Muschl. for chromosome 5B of cv. Chinese Spring. The deletion was terminal with a breakpoint just proximal to the interstitial C-band. The degree of metaphase I chromosome pairing in plants homozygous for the deletion indicated that the chromosome pairing promoting gene known to be in the p arm of chromosome 5B is located in the deleted portion of that arm. Additionally, all of the 5S ribosomal RNA genes known to exist on arm 5Bp were mapped to this deleted portion.Key words: C-banding, 5S rRNA genes, Triticum, Aegilops chromosome aberration.


Genome ◽  
1994 ◽  
Vol 37 (3) ◽  
pp. 477-481 ◽  
Author(s):  
Jie Xu ◽  
R. L. Conner ◽  
A. Laroche

'Agrotana', a wheat-alien hybrid (2n = 56), is a potential source of resistance to common root rot, stem rust, wheat streak mosaic virus, and the wheat curl mite. However, the origin of 'Agrotana', reported to be durum wheat × Agropyron trichophorum (pubescent wheatgrass), is uncertain. The objective of this investigation was to determine the chromosome constitution of 'Agrotana' using C-banding and fluorescence in situ hybridization techniques. The F1 hybrid of 'Agrotana' × 'Chinese Spring' wheat showed 7 I + 21 II in 14.9% of the pollen mother cells, evidence of the presence of the A, B, and D genomes in 'Agrotana'. The hybrid had 16 heavily C-banded chromosomes, namely 4A, and 1-7B of wheat, and a translocation that probably involved wheat chromosomes 2A and 2D. In situ hybridization using biotinylated genomic DNA of Ag. trichophorum cv. Greenleaf blocked with CS DNA failed to identify the alien chromosomes in 'Agrotana', indicating that the alien chromosomes were not likely derived from pubescent wheatgrass. In situ hybridization using labelled wheat genomic DNA blocked with 'Agrotana' DNA revealed that 'Agrotana' had 40 wheat, 14 alien, and 2 (a pair) wheat–alien translocated chromosomes. There was no homology between wheat and the alien chromosomes or chromosome segments involved in the wheat–alien recombinant. Two of the seven pairs of alien chromosomes were homoeologous to each other. The ability to identify alien chromatin in wheat using labelled wheat DNA instead of labelled alien DNA will be particularly useful in chromosome engineering of wheat germplasms having alien chromatin of unknown origin.Key words: wheat–alien hybrid, C-banding, fluorescence in situ hybridization, labelled wheat DNA as probe.


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