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.

Population genetics and phylogenetic analysis of the vrs1 nucleotide sequence in wild and cultivated barley

Genome ◽  
2014 ◽  
Vol 57 (4) ◽  
pp. 239-244 ◽  
Author(s):  
Xifeng Ren ◽  
Yonggang Wang ◽  
Songxian Yan ◽  
Dongfa Sun ◽  
Genlou Sun
Keyword(s):  
Population Genetics ◽  
Phylogenetic Analysis ◽  
Genetic Variation ◽  
Hordeum Vulgare ◽  
Nucleotide Diversity ◽  
Wild Barley ◽  
Haplotype Diversity ◽  
Lateral Spikelet ◽  
Cultivated Barley ◽  
Barley Population

Spike morphology is a key characteristic in the study of barley genetics, breeding, and domestication. Variation at the six-rowed spike 1 (vrs1) locus is sufficient to control the development and fertility of the lateral spikelet of barley. To study the genetic variation of vrs1 in wild barley (Hordeum vulgare subsp. spontaneum) and cultivated barley (Hordeum vulgare subsp. vulgare), nucleotide sequences of vrs1 were examined in 84 wild barleys (including 10 six-rowed) and 20 cultivated barleys (including 10 six-rowed) from four populations. The length of the vrs1 sequence amplified was 1536 bp. A total of 40 haplotypes were identified in the four populations. The highest nucleotide diversity, haplotype diversity, and per-site nucleotide diversity were observed in the Southwest Asian wild barley population. The nucleotide diversity, number of haplotypes, haplotype diversity, and per-site nucleotide diversity in two-rowed barley were higher than those in six-rowed barley. The phylogenetic analysis of the vrs1 sequences partially separated the six-rowed and the two-rowed barley. The six-rowed barleys were divided into four groups.

Extraordinarily polymorphic ribosomal DNA in wild and cultivated rice

Genome ◽  
1996 ◽  
Vol 39 (6) ◽  
pp. 1109-1116 ◽  
Author(s):  
K. D. Liu ◽  
Qifa Zhang ◽  
G. P. Yang ◽  
M. A. Saghai Maroof ◽  
S. H. Zhu ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Ribosomal Dna ◽  
Wild Rice ◽  
Indica Rice ◽  
Intergenic Spacer ◽  
Oryza Rufipogon ◽  
Japonica Rice ◽  
Cultivated Rice ◽  
Spacer Length ◽  
Origin And Evolution

A collection of 481 rice accessions was surveyed for ribosomal DNA (rDNA) intergenic spacer length polymorphism to assess the extent of genetic diversity in Chinese and Asian rice germplasm. The materials included 83 accessions of common wild rice, Oryza rufipogon, 75 of which were from China; 348 entries of cultivated rice (Oryza sativa), representing almost all the rice growing areas in China; and 50 cultivars from South and East Asia. A total of 42 spacer length variants (SLVs) were detected. The size differences between adjacent SLVs in the series were very heterogeneous, ranging from ca. 21 to 311 bp. The 42 SLVs formed 80 different rDNA phenotypic combinations. Wild rice displayed a much greater number of rDNA SLVs than cultivated rice, while cultivated rice showed a larger number of rDNA phenotypes. Indica and japonica groups of O. sativa contained about equal numbers of SLVs, but the SLV distribution was significantly differentiated: indica rice was preferentially associated with longer SLVs and japonica rice with shorter ones. The results may have significant implications regarding the origin and evolution of cultivated rice, as well as the inheritance and molecular evolution of rDNA intergenic spacers in rice. Key words : rDNA, Oryza rufipogon, Oryza sativa, germplasm diversity, evolution.

scholarly journals MULTILOCUS STRUCTURE OF NATURAL POPULATIONS OF HORDEUM SPONTANEUM

Genetics ◽  
1980 ◽  
Vol 96 (2) ◽  
pp. 523-536 ◽  
Author(s):  
A H D Brown ◽  
M W Feldman ◽  
E Nevo
Keyword(s):  
Wild Barley ◽  
Natural Populations ◽  
Hordeum Spontaneum ◽  
Wild Populations ◽  
Allozyme Data ◽  
Complete Independence ◽  
Esterase Loci ◽  
Cultivated Barley ◽  
Gametic Phase Disequilibrium ◽  
Gametic Phase

ABSTRACT The association of alleles among different loci was studied in natural populations of Hordeum spontaneum, the evolutionary progenitor of cultivated barley. The variance of the number of heterozygous loci in two randomly chosen gametes affords a useful measure of such association. The behavior of this statistic in several particular models is described. Generally, linkage (gametic phase) disequilibrium tends to increase the variance above the value expected under complete independence. This increase is greatest when disequilibria are such as to maximize the sum of squares of the two-locus gametic frequencies.—When data on several loci per individual are available, the observed variance may be tested for its agreement with that expected under the hypothesis of complete interlocus independence, using the sampling theory of this model. When applied to allozyme data from 26 polymorphic populations of wild barley, this test demonstrated the presence of geographically widespread multilocus organization. On average, the variance was 80% higher than expected under random association. Gametic frequencies for four esterase loci in both of these populations of wild barley and two composite crosses of cultivated barley were analyzed. Most generations of the composites showed less multilocus structure, as measured by the indices of association, than the wild populations.

COMPARATIVE ASSESSMENT OF GENETIC DIVERSITY IN WILD AND CULTIVATED BARLEY USING RIBOSOMAL DNA SPACER LENGTH VARIANTS

1994 ◽  
Vol 42 (2) ◽  
pp. 115-123 ◽  
Author(s):  
Jeyanthi Ramamoorthy ◽  
Daniel K. Chong ◽  
C.C. Chinnappa
Keyword(s):  
Genetic Diversity ◽  
Ribosomal Dna ◽  
Mediterranean Region ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Hordeum Spontaneum ◽  
Spacer Length ◽  
Frequency Distributions ◽  
Cultivated Barley ◽  
Spacer Length Variants

Ribosomal DNA spacer length variants (slv) were used to compare the genetic diversity between Hordeum spontaneum, the supposed progenitor of cultivated barley, and landraces of barley, H. vulgare, collected from three countries in the eastern Mediterranean region. A total of six rDNA slv and six slv phenotypes were observed. All six slv and phenotypes were found in both species. Nei's heterozygosity index was higher for landraces in all three countries. Landraces possessed slightly higher diversity than H. spontaneum. Slv phenotype 1 (112, 104) was the most predominant type in both species, and the frequency distributions for the two species were similar. This suggests that H. vulgare and H. spontaneum belong to the same polymorphic species. Furthermore, H. spontaneum seen today in the eastern Mediterranean region might have been derived from an extinct two-rowed ancestor.

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

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.

scholarly journals Genetic variation at flowering time loci in wild and cultivated barley

2011 ◽  
Vol 9 (2) ◽  
pp. 264-267 ◽  
Author(s):  
James Cockram ◽  
Huw Hones ◽  
Donal M. O'Sullivan
Keyword(s):  
Genetic Variation ◽  
Flowering Time ◽  
Wild Barley ◽  
Agronomic Traits ◽  
Allelic Variation ◽  
Allelic Diversity ◽  
Early Flowering ◽  
Day Length ◽  
Wild Germplasm ◽  
Cultivated Barley

The worldwide spread of barley cultivation required adaptation to agricultural environments far distant from those found in its centre of domestication. An important component of this adaptation is the timing of flowering, achieved predominantly in response to day length and temperature. Here, we use a collection of cultivars, landraces and wild barley accessions to investigate the origins and distribution of allelic diversity at four major flowering time loci, mutations at which have been under selection during the spread of barley cultivation into Europe. Our findings suggest that while mutant alleles at the PPD-H1 and PPD-H2 photoperiod loci occurred pre-domestication, the mutant vernalization non-responsive alleles utilized in landraces and cultivars at the VRN-H1 and VRN-H2 loci occurred post-domestication. The transition from wild to cultivated barley is associated with a doubling in the number of observed multi-locus flowering-time haplotypes, suggesting that the resulting phenotypic variation has aided adaptation to cultivation in the diverse ecogeographic locations encountered. Despite the importance of early-flowering alleles during the domestication of barley in Europe, we show that novel VRN alleles associated with early flowering in wild barley have been lost in domesticates, highlighting the potential of wild germplasm as a source of novel allelic variation for agronomic traits.

scholarly journals Evolution of the Ribosomal DNA Spacers of Drosophila melanogaster: Different Patterns of Variation on X and Y Chromosomes

Genetics ◽  
1987 ◽  
Vol 116 (2) ◽  
pp. 225-232
Author(s):  
Scott M Williams ◽  
Glenn R Furnier ◽  
Eric Fuog ◽  
Curtis Strobeck
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Selection ◽  
Ribosomal Dna ◽  
Genomic Dna ◽  
Restriction Enzymes ◽  
Ribosomal Gene ◽  
Length Variation ◽  
Spacer Length ◽  
Y Chromosomes ◽  
The World

ABSTRACT Length variation of the ribosomal gene spacers of Drosophila melanogaster was studied. Analysis of 47 X chromosomal and 47 Y chromosomal linked rDNA arrays collected from five continents indicates that the arrays on the two chromosomes differ qualitatively. The Y-linked arrays from around the world share little or no similarity for either their overall length or the organization of their spacers. Most of the X-linked arrays do, however, share a major length spacer of 5.1 kb. In addition, those X-linked arrays that have a major 5.1-kb band have similar spacer organization as demonstrated by genomic DNA digestions with several restriction enzymes. These data strongly support the hypothesis that spacer length patterns on only X-linked genes are maintained primarily by natural selection.

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