Genetic analyses of rDNA spacer-length variation in barley

1993 ◽  
Vol 85-85 (6-7) ◽  
pp. 913-919 ◽  
Author(s):  
K. M. Soliman
Keyword(s):  
Length Variation ◽  
Genetic Analyses ◽  
Spacer Length

A comparative analysis of genetic polymorphism in wild and cultivated barley from Tibet using isozyme and ribosomal DNA markers

Genome ◽  
1994 ◽  
Vol 37 (4) ◽  
pp. 631-638 ◽  
Author(s):  
Qifa Zhang ◽  
G. P. Yang ◽  
Xiankai Dai ◽  
J. Z. Sun
Keyword(s):  
Genetic Variation ◽  
Ribosomal Dna ◽  
Wild Barley ◽  
Length Variation ◽  
Spacer Length ◽  
Origin And Evolution ◽  
Centre Of Diversity ◽  
Esterase Loci ◽  
Cultivated Barley ◽  
Comparison Of The Results

This study was conducted to address some of the issues concerning the possible significance of Tibet in the origin and evolution of cultivated barley. A total of 1757 barley accessions from Tibet, including 1496 entries of Hordeum vulgare ssp. vulgare (HV), 229 entries of the six-rowed wild barley H. vulgare ssp. agriocrithon (HA), and 32 entries of the two-rowed wild barley H. vulgare ssp. spontaneum (HS), were assayed for allozymes at four esterase loci. A subsample of 491 accessions was surveyed for spacer-length polymorphism at two ribosomal DNA loci. Genetic variation is extensive in these barley groups, and the amount of genetic diversity in cultivated barley of this region is comparable with that of cultivated barley worldwide. The level of genetic variation of HA is significantly lower than the other two barley groups, and there is also substantial heterogeneity in the level of polymorphism among different agrigeographical subregions. However, little genetic differentiation was detected among the three barley groups (HV, HA, and HS), as well as among different agrigeographical subregions. Comparison of the results from this and previous studies indicated a strong differentiation between Oriental and Occidental barley, thus favoring the hypothesis of a diphyletic origin of cultivated barley.Key words: Hordeum, allozyme, rDNA spacer-length variation, centre of diversity, phylogeny.

Length and sequence heterogeneity in 5S rDNA of Populus deltoides

Genome ◽  
2002 ◽  
Vol 45 (6) ◽  
pp. 1181-1188 ◽  
Author(s):  
Madan S Negi ◽  
Jyothi Rajagopal ◽  
Neeti Chauhan ◽  
Richard Cronn ◽  
Malathi Lakshmikumaran
Keyword(s):  
Populus Deltoides ◽  
5S Rdna ◽  
Rrna Genes ◽  
Length Variation ◽  
Spacer Length ◽  
Sequence Heterogeneity ◽  
Distance Analysis ◽  
Repeat Units ◽  
Class 1 ◽  
Dna Microsatellite

The 5S rRNA genes and their associated non-transcribed spacer (NTS) regions are present as repeat units arranged in tandem arrays in plant genomes. Length heterogeneity in 5S rDNA repeats was previously identified in Populus deltoides and was also observed in the present study. Primers were designed to amplify the 5S rDNA NTS variants from the P. deltoides genome. The PCR-amplified products from the two accessions of P. deltoides (G3 and G48) suggested the presence of length heterogeneity of 5S rDNA units within and among accessions, and the size of the spacers ranged from 385 to 434 bp. Sequence analysis of the non-transcribed spacer (NTS) revealed two distinct classes of 5S rDNA within both accessions: class 1, which contained GAA trinucleotide microsatellite repeats, and class 2, which lacked the repeats. The class 1 spacer shows length variation owing to the microsatellite, with two clones exhibiting 10 GAA repeat units and one clone exhibiting 16 such repeat units. However, distance analysis shows that class 1 spacer sequences are highly similar inter se, yielding nucleotide diversity (π) estimates that are less than 0.15% of those obtained for class 2 spacers (π = 0.0183 vs. 0.1433, respectively). The presence of microsatellite in the NTS region leading to variation in spacer length is reported and discussed for the first time in P. deltoides.Key words: 5S rDNA, Populus, repetitive DNA, microsatellite, sequence heterogeneity.

scholarly journals Ferroelectric liquid-crystalline side group polymers Spacer length variation and comparison with the monomers

1993 ◽  
Vol 14 (3) ◽  
pp. 861-869 ◽  
Author(s):  
K. Kühnpast ◽  
J. Springer ◽  
G. Scherowsky ◽  
F. Gießelmann ◽  
P. Zugenmaier
Keyword(s):  
Liquid Crystalline ◽  
Length Variation ◽  
Side Group ◽  
Spacer Length

Temporal variation in the ribosomal DNA nontranscribed spacer of Aedes albopictus (Diptera: Culicidae)

Genome ◽  
1991 ◽  
Vol 34 (2) ◽  
pp. 293-297 ◽  
Author(s):  
Srinivas Kambhampati ◽  
Karamjit S. Rai
Keyword(s):  
Temporal Variation ◽  
Aedes Albopictus ◽  
Ribosomal Dna ◽  
Population Variation ◽  
High Rate ◽  
Length Variation ◽  
Spacer Length ◽  
Nontranscribed Spacer ◽  
Population Component ◽  
Different Populations

Length variation in ribosomal DNA (rDNA) nontranscribed spacer within and among populations of the mosquito Aedes albopictus was studied over a 3-year period in eight different populations from Texas. Statistically significant variation was detected among populations at each sampling date. Significant, but nondirectional, changes were observed within populations over time. An average of 78% of the total variance in the frequencies of spacer variants was attributable to the within-population component, suggesting local differentiation. The results corroborate those from a previous study on spacer length diversity in populations of A. albopictus from around the world and are similar to those from a study on temporal variation in allozyme frequencies in some of the same populations and sampling dates. We propose that a high rate of production of length variants and localized breeding structure could explain the observed high levels of within- and among-population variation in A. albopictus.Key words: rDNA, nontranscribed spacer, genetic structure, temporal variation, Aedes albopictus.

Ribosomal DNA spacer-length variation inSecale spp. (Poaceae)

1990 ◽  
Vol 171 (1-4) ◽  
pp. 205-220 ◽  
Author(s):  
P. Reddy ◽  
R. Appels ◽  
B. R. Baum
Keyword(s):  
Ribosomal Dna ◽  
Length Variation ◽  
Spacer Length

Control of Charge-Carrier Mobility via In-Chain Spacer Length Variation in Sequenced Triarylamine Functionalized Polyolefins

2012 ◽  
Vol 1 (2) ◽  
pp. 324-327 ◽  
Author(s):  
Brian S. Aitken ◽  
Patrick M. Wieruszewski ◽  
Kenneth R. Graham ◽  
John R. Reynolds ◽  
Kenneth B. Wagener
Keyword(s):  
Charge Carrier ◽  
Carrier Mobility ◽  
Charge Carrier Mobility ◽  
Length Variation ◽  
Spacer Length

Variation of the intergenic spacer region of ribosomal DNA in cultivated and wild rice species

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 209-218 ◽  
Author(s):  
Y. Sano ◽  
R. Sano
Keyword(s):  
Ribosomal Dna ◽  
Intergenic Spacer ◽  
Length Variation ◽  
Cultivated Rice ◽  
Spacer Length ◽  
Intergenic Spacer Region ◽  
Wild Rice Species ◽  
Cultivated Species ◽  
Restriction Enzyme Maps ◽  
Spacer Length Variants

Spacer-length variation in ribosomal DNA (rDNA) was surveyed in two cultivated rice species and their wild relatives. Among 243 accessions observed, 18 different spacer-length variants were detected. Length heterogeneity was found within and among species as well as within individuals. Conventional genetic analysis revealed that two spacer-length variants were located at two unlinked loci. Restriction enzyme maps showed that length heterogeneity resulted from repetition of short repeated sequences in the intergenic spacer region in the Asian cultivar and its progenitor; however, the spacer region greatly differed from those of reproductively isolated taxa with respect to the length and the sequence. Furthermore, the Asian cultivated species and its progenitor were highly polymorphic for rDNA spacer-length variation and they were differentiated in frequencies of spacer-length variants as well as varietal groups within the cultivated species. Asian cultivars tended to carry homogeneous repeats of rDNA compared with their progenitor, suggesting different forms of homogenization occurring in Asian cultivars.Key words: ribosomal DNA, intergenic spacer, polymorphism, inheritance, Oryza.

On the Control of Chromophore Orientation, Supramolecular Structure, and Thermodynamic Stability of an Amphiphilic Pyridyl-Thiazol upon Lateral Compression and Spacer Length Variation

2017 ◽  
Vol 9 (50) ◽  
pp. 44181-44191 ◽  
Author(s):  
Maximilian L. Hupfer ◽  
Martin Kaufmann ◽  
Felix Herrmann-Westendorf ◽  
Torsten Sachse ◽  
Ludovic Roussille ◽  
...  
Keyword(s):  
Thermodynamic Stability ◽  
Supramolecular Structure ◽  
Length Variation ◽  
Lateral Compression ◽  
Spacer Length

Variation of nuclear ribosomal RNA genes in Eragrostis tef (Zucc.) Trotter

Genome ◽  
1997 ◽  
Vol 40 (6) ◽  
pp. 815-821 ◽  
Author(s):  
Michael Pillay
Keyword(s):  
Ribosomal Rna ◽  
Restriction Site ◽  
Ribosomal Rna Genes ◽  
Rrna Genes ◽  
Eragrostis Tef ◽  
Length Variation ◽  
Rdna Repeat ◽  
Spacer Length ◽  
Repeat Units ◽  
Rna Genes

Variation in the ribosomal RNA genes (rDNA) was examined to assess the genetic variability among 314 plants representing 28 accessions of Eragrostis tef, an important food crop. A restriction site map was constructed for the species by localization of the BamHI, BglII, DraI, EcoRI, EcoRV, NdeI, SacI, SpeI, XbaI, and XhoI sites. A comparison of this map with those of other grasses showed conservation of sites, especially in the coding region. However, a unique EcoRI site combined with a BamHI site in the 18S region may be of diagnostic value for the species. A BamHI fragment that spans the intergenic spacer was used as an indicator of length variation of rDNA repeat units. rDNA repeat units in E. tef ranged in size from 8.4 to 11.07 kbp. Considerable size variation of rDNA repeats was present among accessions, between individual plants within some accessions, and within single plants. A total of 19 spacer length (sl) phenotypes was observed in 16 accessions in which 11–42 plants were analyzed. A single restriction site polymorphism was detected in PI442115 that was also distinguished by having a single sl variant. Variation in the rRNA genes is a useful indicator of genetic diversity in E. tef germplasm.Key words: Eragrostis tef, ribosomal DNA, restriction map, genetic variation.

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