Hypervariation associated with a 12-nucleotide direct repeat and inferences on intergenomic homogenization of ribosomal RNA gene spacers based on the DNA sequence of a clone from the wheat Nor-D3 locus

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 770-781 ◽  
Author(s):  
Michael Lassner ◽  
Olin Anderson ◽  
Jan Dvořák
Keyword(s):  
Dna Sequence ◽  
Ribosomal Rna ◽  
Consensus Sequence ◽  
Direct Repeat ◽  
Triticum Aestivum L ◽  
Sequence Information ◽  
D Genome ◽  
Ribosomal Rna Gene ◽  
Nontranscribed Spacer ◽  
B Genome

A ribosomal RNA gene (rDNA) unit from the Nor-D3 locus (D genome) of Triticum aestivum L. was cloned and the "nontranscribed spacer" (NTS) was sequenced. The DNA sequence was compared with previously reported Nor-B2 locus (B genome) NTS sequences to study the molecular basis of evolution of these repeated genes and to look for evidence of homogenization between B- and D-genome rDNA. The NTS has seven subrepeats with a modal repeat length of 120 nucleotides; the subrepeats are shorter than Nor-B2 subrepeats owing to loss of one element of a 12-bp duplication present in Nor-B2 subrepeats. This 12 nucleotide sequence or its permutation, whose consensus sequence is CACGTACACGGA, is found at all sites where the B- and D-genome rDNA spacers differ by insertions or deletions longer than two nucleotides. The DNA sequence information was used to identify restriction sites unique to each locus that could be used in search of conversions between the B- and D-genome rDNA loci. Despite the coexistence of rDNA of the B- and D-genomes in the same nucleus for a minimum of 8000 years, no evidence for frequent interchromosomal conversion events between chromosomes 1B or 6B and 5D was found. Key words: Triticum, rDNA, concerted evolution, spacer.

Towards a molecular taxonomy for the bloom-forming cyanobacteria

1994 ◽  
Vol 45 (5) ◽  
pp. 869 ◽  
Author(s):  
BA Neilan ◽  
PR Hawkins ◽  
PT Cox ◽  
AE Goodman
Keyword(s):  
Dna Sequence ◽  
Ribosomal Rna ◽  
Water Samples ◽  
Molecular Taxonomy ◽  
Sequence Information ◽  
Specific Sequence ◽  
Ribosomal Rna Gene ◽  
Toxigenic Strains

Regions of the 16s subunit of the ribosomal RNA gene of the bloom-associated cyanobacterial genera Microcystis and Anabaena have been sequenced and found to provide strain-specific sequence information. Comparisons of the DNA sequence of these cyanobacteria indicated that the strains examined are related and that probes diagnostic for bloom-forming and toxigenic strains in water samples can be designed.

scholarly journals A Microsatellite Map of Wheat

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 2007-2023 ◽  
Author(s):  
Marion S Röder ◽  
Victor Korzun ◽  
Katja Wendehake ◽  
Jens Plaschke ◽  
Marie-Hélène Tixier ◽  
...  
Keyword(s):  
Bread Wheat ◽  
Reference Population ◽  
Triticum Aestivum L ◽  
Wheat Genome ◽  
D Genome ◽  
B Genome ◽  
Microsatellite Map ◽  
A Genome ◽  
Polymorphic Microsatellite ◽  
Primer Sets

Abstract Hexaploid bread wheat (Triticum aestivum L. em. Thell) is one of the world's most important crop plants and displays a very low level of intraspecific polymorphism. We report the development of highly polymorphic microsatellite markers using procedures optimized for the large wheat genome. The isolation of microsatellite-containing clones from hypomethylated regions of the wheat genome increased the proportion of useful markers almost twofold. The majority (80%) of primer sets developed are genome-specific and detect only a single locus in one of the three genomes of bread wheat (A, B, or D). Only 20% of the markers detect more than one locus. A total of 279 loci amplified by 230 primer sets were placed onto a genetic framework map composed of RFLPs previously mapped in the reference population of the International Triticeae Mapping Initiative (ITMI) Opata 85 × W7984. Sixty-five microsatellites were mapped at a LOD >2.5, and 214 microsatellites were assigned to the most likely intervals. Ninety-three loci were mapped to the A genome, 115 to the B genome, and 71 to the D genome. The markers are randomly distributed along the linkage map, with clustering in several centromeric regions.

The genomic inheritance of aluminum tolerance in 'Atlas 66' wheat

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 689-693 ◽  
Author(s):  
William A. Berzonsky
Keyword(s):  
Root Growth ◽  
Aluminum Tolerance ◽  
Triticum Aestivum L ◽  
Nuclear Genes ◽  
D Genome ◽  
Hard Red Spring Wheat ◽  
Al Stress ◽  
Soft Red Winter Wheat ◽  
B Genome ◽  
Segregation Ratios

Toxicity to aluminum (Al) limits wheat (Triticum aestivum L. em. Thell.) yields. 'Atlas 66', a soft red winter wheat classified as tolerant (root growth ≥ 0.5 cm after Al stress) to 0.44 mM Al, was hybridized with tetraploid (4x) and hexaploid (6x) 'Canthatch', a hard red spring wheat classified as sensitive (root growth < 0.5 cm after Al stress) to 0.44 mM Al. Progenies produced from these hybridizations were tested for tolerance to 0.44 mM Al in solution to ascertain the number of genes and the genomes of 'Atlas 66', which determine tolerance to aluminum. Tests of 'Atlas 66', 6x-'Canthatch', and the F1's resulting from hybridizations between the parents indicated that dominant, nuclear genes carried by 'Atlas 66' determine tolerance to 0.44 mM Al. Segregation ratios for the F2 significantly differed from ratios expected for a dominant, duplicate genetic mechanism. F1 backcross segregation ratios did not significantly differ from ratios expected for dominant, duplicate nuclear genes for tolerance to aluminum. The expression of genes for tolerance to 0.44 mM Al for 'Atlas 66' appears to be more complex than is predicted by the existence of two dominant genes. A crossing scheme, which involved hybridizing 4x-'Canthatch' with 'Atlas 66', was executed to produce 42-chromosome plants having recombinant A- and B-genome chromosomes and D-genome chromosomes derived exclusively from 'Atlas 66'. Eleven F6 and F7 lines, developed from these plants, were selfed and plants in the F6 generation were backcrossed to 'Atlas 66' and 6x-'Canthatch'. The F6 and F7 lines were subjected to 0.44 mM Al in solution as were the backcrosses. While none of the lines had more than 50% of their seedlings classified as sensitive to Al in the F6 generation, four lines exhibited such a response in the F7 generation. In general, backcrossing the F6 lines to 6x-'Canthatch' increased sensitivity to Al, while backcrossing to 'Atlas 66' increased tolerance. Results suggest that genes for tolerance to Al in 'Atlas 66' wheat are not all located on D-genome chromosomes.Key words: aluminum tolerance, genomic inheritance, Triticum.

Genetic Relationship Among Indian Termites Based on DNA Sequence of Mitochondrial 12S Ribosomal RNA Gene

2015 ◽  
Vol 02 (01) ◽  
Author(s):  
Mandakini Singla Vijay Lakshmi ◽  
Sharma Ranbir Chander Sobti ◽  
Monika Sodhi Mamtesh Kumari
Keyword(s):  
Dna Sequence ◽  
Ribosomal Rna ◽  
Genetic Relationship ◽  
Ribosomal Rna Gene

scholarly journals The intergenic spacer region of the ribosomal RNA gene of Penicillium marneffei shows almost no DNA sequence diversity

2010 ◽  
Vol 54 (11) ◽  
pp. 714-716 ◽  
Author(s):  
Nanthawan Mekha ◽  
Takashi Sugita ◽  
Koichi Makimura ◽  
Natteewan Poonwan ◽  
Pathom Sawanpanyalert ◽  
...  
Keyword(s):  
Dna Sequence ◽  
Ribosomal Rna ◽  
Intergenic Spacer ◽  
Sequence Diversity ◽  
Penicillium Marneffei ◽  
Ribosomal Rna Gene ◽  
Intergenic Spacer Region

scholarly journals Novel fluorescent sequence-related amplified polymorphism(FSRAP) markers for the construction of a genetic linkage map of wheat(Triticum aestivum L.)

Genetika ◽  
2017 ◽  
Vol 49 (3) ◽  
pp. 1081-1093 ◽  
Author(s):  
Lingbo Zhao ◽  
Zhang Li ◽  
Jipeng Qu ◽  
Yan Yu ◽  
Lu Lu ◽  
...  
Keyword(s):  
Genetic Linkage Map ◽  
Average Distance ◽  
Triticum Aestivum L ◽  
Genetic Maps ◽  
The Novel ◽  
Linkage Groups ◽  
D Genome ◽  
Wheat Varieties ◽  
B Genome ◽  
A Genome

Novel fluorescent sequence-related amplified polymorphism (FSRAP) markers were developed based on the SRAP molecular marker. Then, the FSRAP markers were used to construct the genetic map of a wheat (Triticum aestivumL.) recombinant inbred line population derived from a Chuanmai 42?Chuannong 16 cross. Reproducibility and polymorphism tests indicated that the FSRAP markers have repeatability and better reflect the polymorphism of wheat varieties compared with SRAP markers. A total of 430 polymorphic loci between Chuanmai 42 and Chuannong 16 were detected with 189 FSRAP primer combinations. A total of 281 FSARP markers and 39 SSR markers re classified into 20 linkage groups. The maps spanned a total length of 2499.3cM with an average distance of 7.81cM between markers. A total of 201 markers were mapped on the B genome and covered a distance of 1013cM. On the A genome, 84 markers were mapped and covered a distance of 849.6cM. On the D genome, however, only 35 markers were mapped and covered a distance of 636.7cM. No FSRAP markers were distributed on the 7D chromosome. The results of the present study revealed that the novel FSRAP markers can be used to generate dense, uniform genetic maps of wheat.

Variability in wheat based on low-copy DNA sequence comparisons

Genome ◽  
1995 ◽  
Vol 38 (5) ◽  
pp. 951-957 ◽  
Author(s):  
L. E. Talbert ◽  
N. K. Blake ◽  
E. W. Storlie ◽  
M. Lavin
Keyword(s):  
Dna Sequence ◽  
Diploid Species ◽  
Sequence Variability ◽  
D Genome ◽  
Sequence Comparisons ◽  
Molecular Analyses ◽  
B Genome ◽  
Hybridization Event ◽  
Copy Dna ◽  
Diploid Ancestor

The chromosomes of the B genome of hexaploid wheat (AABBDD) do not pair completely with those of any of the diploid species with genomes similar to B. Various biochemical and molecular analyses have suggested that each of the five diploid species in section Sitopsis of Triticum are ancestral to B. These observations have led to the hypothesis that the B genome may be polyphyletic, descending from more than one diploid ancestor. This hypothesis may account for differences between the wheat B genome and the diploids and also for variability that currently exists among different wheat accessions. In this study, we cloned and compared nucleotide sequences for three low-copy DNA fragments from the B and D genomes of several wheat accessions and from diploid relatives of the B and D genomes. Our results suggested that the amount of DNA sequence variability in wheat is low, although somewhat more variability existed in the B genome than in the D genome. The B genome of wheat was significantly diverged from all the Sitopsis diploid species, and Triticum speltoides was closer to B than to other members of this section. The D genome of wheat was very similar to that of its progenitor, Triticum tauschii. No evidence for a polyphyletic origin of the B genome was found. A more parsimonious hypothesis is that the wheat B genome diverged from its diploid ancestor after the original hybridization event occurred.Key words: wheat, low-copy DNA, phylogenetics.

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