Variation among alfalfa somaclones in copy number of repeated DNA sequences

Genome ◽  
1993 ◽  
Vol 36 (5) ◽  
pp. 906-912 ◽  
Author(s):  
K. K. Kidwell ◽  
T. C. Osborn
Keyword(s):  
Dna Sequences ◽  
Copy Number ◽  
Southern Blot Analysis ◽  
Tandem Repeats ◽  
Nuclear Dna ◽  
Slot Blot ◽  
Repeated Dna ◽  
Repeated Dna Sequences ◽  
Hybridization Intensity ◽  
Medicago Sativa L

Repeated DNA sequences of alfalfa (Medicago sativa L.) somaclonal variants were analyzed to determine if changes in copy number had occurred during tissue culture. DNA clones containing highly repeated nuclear sequences from the diploid line HG2 (2x = 16) were slot blotted and probed with labeled DNAs from HG2 and several somaclones of HG2. Two DNA clones that differed visually in hybridization intensity among the plant DNAs and one clone that had constant hybridization intensity were selected and used as probes on Southern blots and slot blots containing equal quantities of DNAs from HG2 and 15 régénérants. Statistically significant differences were detected in the copy number of two anonymous DNA sequences initially selected as variable and in the copy number of sequences homologous to pea ribosomal DNA. Based on Southern blot analysis, these sequences appeared to be arranged as tandem repeats. The cloned sequence initially selected as stable did not vary significantly in copy number and it appeared to be arranged as a dispersed repeat. Both increases and decreases in copy number of repeated sequences were observed in plants from successive regeneration cycles. Results from this study indicate that specific repeated nuclear DNA sequences have changed copy number in plants regenerated from tissue culture.Key words: somaclonal variation, repeated DNA, slot blot, quantitative variation.

Genomic organization, evolution, and structural peculiarities of highly repetitive DNA of Hordeum vulgare

Genome ◽  
1990 ◽  
Vol 33 (3) ◽  
pp. 441-449 ◽  
Author(s):  
A. V. Vershinin ◽  
E. A. Salina ◽  
V. V. Solovyov ◽  
L. L. Timofeyeva
Keyword(s):  
Hordeum Vulgare ◽  
Dna Sequences ◽  
Genome Organization ◽  
Copy Number ◽  
Repetitive Sequences ◽  
Repeated Dna ◽  
Repeated Dna Sequences ◽  
Highly Repeated Dna ◽  
Structural Peculiarities ◽  
Hordeum Jubatum

A fraction of highly repeated DNA sequences of Hordeum vulgare has been investigated by cloning 19 separate highly repetitive sequences in the plasmid pBR327. Characteristics studied included genus specificity of isolated sequences, their prevalence, and genome organization. Sequences (pHv7161, pHv7191, pHv7179) have been identified that are the most widespread in the H. vulgare genome and have a complicated arrangement. A tandemly arranged sequence, pHv7141, was also identified. The primary structure of a 999 bp long, BamHI fragment of one of the most widespread sequences, pHv7161, as well as the adjacent pHv7302 and pHv7245 sequences was determined. The fragment abounds in inverted repeats, of which two are flanked by direct repeats, and contains short subrepeats, A, B, and C, and a great variety of potential protein-binding sites. A comparison is drawn between the content and genome organization of highly repeated DNA sequences of H. vulgare and those of the wild barley species Hordeum bulbosum, Hordeum jubatum, Hordeum geniculatum, Hordeum brevisubulatum, Hordeum turkestanicum, and Hordeum murinum. According to the above characters (close copy number and genome organization similarity of highly repetitive sequences) the species under discussion have been classified into four groups. This division is in good agreement with other data on interspecific crossing in Hordeum and on chromosome pairing in hybrid meiosis.Key words: Hordeum, highly repeated DNA sequences, copy number.

Highly repeated DNA sequences in birds: The structure and evolution of an abundant, tandemly repeated 190-bp DNA fragment in parrots

Genomics ◽  
1992 ◽  
Vol 14 (2) ◽  
pp. 462-469 ◽  
Author(s):  
Cort S. Madsen ◽  
Dineke H. de Kloet ◽  
Jean E. Brooks ◽  
Siwo R. de Kloet
Keyword(s):  
Dna Sequences ◽  
Repeated Dna ◽  
Repeated Dna Sequences ◽  
Highly Repeated Dna ◽  
Dna Fragment

Polymerase chain reaction based mapping of rye involving repeated DNA sequences

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 621-626 ◽  
Author(s):  
Peter M. Rogowsky ◽  
Ken W. Shepherd ◽  
Peter Langridge
Keyword(s):  
Polymerase Chain Reaction ◽  
Dna Sequences ◽  
Chromosome 1 ◽  
Repeated Dna ◽  
Chain Reaction ◽  
Pcr Marker ◽  
Banding Patterns ◽  
Repeated Dna Sequences ◽  
Cereal Rye ◽  
Polymerase Chain

A novel type of polymerase chain reaction (PCR) marker was developed for the mapping of cereal rye (Secale cereale). Primer pairs were synthesized targeting the insertion sites of three individual copies of the R173 family of rye specific repeated DNA sequences. While one primer was derived from a sequence within the respective R173 element, the second primer corresponded to a flanking region. The complex banding patterns obtained in rye allowed not only the mapping of the three R173 elements to certain chromosome regions of 1RS (the short arm of rye chromosome 1) but also the mapping of an additional 3–10 easily identifiable bands per primer pair to other rye chromosomes. Linkage mapping of a polymorphic 1R band derived from three rye cultivars demonstrated the presence of nonallelic, dominant markers in two independent crosses. Because of the high copy number of the R173 family (15 000 copies per diploid rye genome), its dispersion over the entire length of all chromosomes and the high number of markers obtained per primer pair, PCR markers based on the R173 family provide an almost unlimited source for well-spaced markers in rye mapping.Key words: polymerase chain reaction, mapping, repetitive DNA sequences, wheat, rye.

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