Change in ribosomal DNA spacer-length composition in maize recurrent selection populations. 2. Analysis of BS10, BS11, RBS10, and RSSSC

1996 ◽  
Vol 92 (6) ◽  
pp. 680-687 ◽  
Author(s):  
B. Kaufman ◽  
T. R. Rocheford ◽  
R. J. Lambert ◽  
A. R. Hallauer
Keyword(s):  
Ribosomal Dna ◽  
Recurrent Selection ◽  
Spacer Length

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.

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.

Molecular cloning and characterization of an unusually large intergenic spacer from the Nor-B2 locus of hexaploid wheat

Genome ◽  
1996 ◽  
Vol 39 (2) ◽  
pp. 288-292 ◽  
Author(s):  
R. K. Sardana ◽  
R. B. Flavell
Keyword(s):  
Key Words ◽  
Ribosomal Dna ◽  
Hexaploid Wheat ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Intergenic Spacer ◽  
Nucleolar Organizer ◽  
Spacer Length ◽  
Spacer Length Variants

An allelic rDNA variant from the Nor-B2 locus of 'Bezostaya' wheat that forms an especially active nucleolus was cloned and characterized. It carries an unusually large intergenic spacer compared with rDNA units in most other wheat genotypes. The additional intergenic length is in the array of 135-bp A repeats and not in other internal repeats. These A repeats have sequences nearly identical to other A repeats described for other alleles. It is suggested therefore that the more active Nor-B2 locus of 'Bezostaya' may be due to the constituent rDNA units possessing a larger array of A repeats. Key words : ribosomal DNA, nucleolar organizer region, A and B repeats, allelic, spacer length variants.

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.

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