scholarly journals Multiple Hybrid Formation in Natural Populations: Concerted Evolution of the Internal Transcribed Spacer of Nuclear Ribosomal DNA (ITS) in North American Arabis divaricarpa (Brassicaceae)

2003 ◽  
Vol 20 (3) ◽  
pp. 338-350 ◽  
Author(s):  
M. A. Koch
Keyword(s):  
Ribosomal Dna ◽  
North American ◽  
Concerted Evolution ◽  
Internal Transcribed Spacer ◽  
Natural Populations ◽  
Nuclear Ribosomal Dna ◽  
Hybrid Formation

scholarly journals The Evolution of Ribosomal DNA Divergent Paralogues and Phylogenetic Implications

Genetics ◽  
1997 ◽  
Vol 145 (3) ◽  
pp. 821-832 ◽  
Author(s):  
Edward S Buckler ◽  
Anthony Ippolito ◽  
Timothy P Holtsford
Keyword(s):  
Secondary Structure ◽  
Ribosomal Dna ◽  
Concerted Evolution ◽  
Internal Transcribed Spacer ◽  
High Stability ◽  
Nuclear Ribosomal Dna ◽  
Structure Stability ◽  
Phylogenetic Implications ◽  
Ancestral States ◽  
Pcr Conditions

Although nuclear ribosomal DNA (rDNA) repeats evolve together through concerted evolution, some genomes contain a considerable diversity of paralogous rDNA. This diversity includes not only multiple functional loci but also putative pseudogenes and recombinants. We examined the occurrence of divergent paralogues and recombinants in Gossypium, Nicotiana, Tripsacum, Winteraceae, and Zea ribosomal internal transcribed spacer (ITS) sequences. Some of the divergent paralogues are probably rDNA pseudogenes, since they have low predicted secondary structure stability, high substitution rates, and many deamination-driven substitutions at methylation sites. Under standard PCR conditions, the low stability paralogues amplified well, while many high-stability paralogues amplified poorly. Under highly denaturing PCR conditions (i.e., with dimethylsulfoxide), both low- and high-stability paralogues amplified well. We also found recombination between divergent paralogues. For phylogenetics, divergent ribosomal paralogues can aid in reconstructing ancestral states and thus serveas good outgroups. Divergent paralogues can also provide companion rDNA phylogenies. However, phylogeneticists must discriminate among families of divergent paralogues and recombinants or suffer from muddled and inaccurate organismal phylogenies.

scholarly journals Multiple Origins and nrDNA Internal Transcribed Spacer Homeologue Evolution in the Glycine tomentella (Leguminosae) Allopolyploid Complex

Genetics ◽  
2004 ◽  
Vol 166 (2) ◽  
pp. 987-998 ◽  
Author(s):  
Jason T Rauscher ◽  
Jeff J Doyle ◽  
A H D Brown
Keyword(s):  
Molecular Evolution ◽  
Concerted Evolution ◽  
Internal Transcribed Spacer ◽  
Direct Sequencing ◽  
Nuclear Ribosomal Dna ◽  
Nucleolar Dominance ◽  
Future Studies ◽  
Complex Interactions ◽  
Multiple Origins ◽  
Glycine Tomentella

Abstract Despite the importance of polyploidy in the evolution of plants, patterns of molecular evolution and genomic interactions following polyploidy are not well understood. Nuclear ribosomal DNA is particularly complex with respect to these genomic interactions. The composition of nrDNA tandem arrays is influenced by intra- and interlocus concerted evolution and their expression is characterized by patterns such as nucleolar dominance. To understand these complex interactions it is important to study them in diverse natural polyploid systems. In this study we use direct sequencing to isolate and characterize nrDNA internal transcribed spacer (ITS) homeologues from multiple accessions of six different races in the Glycine tomentella allopolyploid complex. The results indicate that in most allopolyploid accessions both homeologous nrDNA repeats are present, but that there are significant biases in copy number toward one homeologue, possibly resulting from interlocus concerted evolution. The predominant homeologue often differs between races and between accessions within a race. A phylogenetic analysis of ITS sequences provides evidence for multiple origins in several of the polyploid races. This evidence for diverse patterns of nrDNA molecular evolution and multiple origins of polyploid races will provide a useful system for future studies of natural variation in patterns of nrDNA expression.

Internal transcribed spacer sequences of nuclear ribosomal DNA resolving complex taxonomic history in the genus Vicia L.

2014 ◽  
Vol 61 (5) ◽  
pp. 909-925 ◽  
Author(s):  
Behrouz Shiran ◽  
Soghra Kiani ◽  
Deepmala Sehgal ◽  
Akram Hafizi ◽  
Tanvir ul-Hassan ◽  
...  
Keyword(s):  
Ribosomal Dna ◽  
Internal Transcribed Spacer ◽  
Nuclear Ribosomal Dna ◽  
Taxonomic History ◽  
Internal Transcribed Spacer Sequences
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