scholarly journals Variability of the genome size in coniferous plant in extreme environmental conditions

1970 ◽  
pp. 37-41
Author(s):  
T. S. Sedelnikova
Keyword(s):  
Genome Size ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Environmental Conditions ◽  
Nuclear Dna ◽  
Chromosomal Rearrangements ◽  
Repetitive Dna Sequences ◽  
Dna Variation ◽  
Nuclear Dna Variation ◽  
Rna Genes

Aim. The features of genome size transformation in conifers growing in extreme environmental conditions are reviewed. Conclusions. Conifers have a very large genome. The main resources of genome size modifications of conifers under extreme environmental conditions are: variability of the chromosome numbers (polyploidy, aneuploidy; mixoploidy), occurrence of B-chromosomes and increasing of its numbers, changes of the content of nuclear DNA, variation of the repetitive DNA sequences (microsatellites, ribosomal RNA genes, transposable elements – retrotransposons), and the chromosomal rearrangements. These features are also components of the epigenetic system which defines the adaptability of the genome changes when exposed to stressful environmental factors. Keywords: Pinophyta, genome, repetitive DNA sequences, epigenetic system.

Repetitive DNA variation and pivotal–differential evolution of wild wheats

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 14-20 ◽  
Author(s):  
L. E. Talbert ◽  
G. Kimber ◽  
G. M. Magyar ◽  
C. B. Buchanan
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
Sympatric Species ◽  
Repetitive Dna Sequences ◽  
Large Set ◽  
Polyploid Species ◽  
Genome Species ◽  
Dna Variation ◽  
Cytogenetic Evidence ◽  
M Genome

Several polyploid species in the genus Triticum contain a U genome derived from the diploid T. umbellulatum. In these species, the U genome is considered to be unmodified from the diploid based on chromosome pairing analysis, and it is referred to as pivotal. The additional genome(s) are considered to be modified, and they are thus referred to as differential genomes. The M genome derived from the diploid T. comosum is found in many U genome polyploids. In this study, we cloned three repetitive DNA sequences found primarily in the U genome and two repetitive DNA sequences found primarily in the M genome. We used these to monitor variation for these sequences in a large set of species containing U and M genomes. Investigation of sympatric and allopatric accessions of polyploid species did not show repetitive DNA similarities among sympatric species. This result does not support the idea that the polyploid species are continually exchanging genetic information through introgression. However, it is also possible that repetitive DNA is not a suitable means of addressing the question of introgression. The U genomes of both diploid and polyploid U genome species were similar regarding hybridization patterns observed with U genome probes. Much more variation was found both among diploid T. comosum accessions and polyploids containing M genomes. The observed variation supports the cytogenetic evidence that the M genome is more variable than the U genome. It also raises the possibility that the differential nature of the M genome may be due to variation within the diploid T. comosum, as well as among polyploid M genome species and accessions.Key words: wheat, molecular, evolution, introgression.

Chromosomal Locations of a Non-LTR Retrotransposon, Menolird18, in Cucumis melo and Cucumis sativus, and Its Implication on Genome Evolution of Cucumis Species

2020 ◽  
Vol 160 (9) ◽  
pp. 554-564
Author(s):  
Agus B. Setiawan ◽  
Chee H. Teo ◽  
Shinji Kikuchi ◽  
Hidenori Sassa ◽  
Kenji Kato ◽  
...  
Keyword(s):  
Genome Evolution ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
18S Rdna ◽  
Cucumis Melo ◽  
Repetitive Dna Sequences ◽  
Ltr Retrotransposon ◽  
Ltr Retrotransposons ◽  
Mitotic Chromosomes ◽  
Rna Genes

Mobile elements are major regulators of genome evolution through their effects on genome size and chromosome structure in higher organisms. Non-long terminal repeat (non-LTR) retrotransposons, one of the subclasses of transposons, are specifically inserted into repetitive DNA sequences. While studies on the insertion of non-LTR retrotransposons into ribosomal RNA genes and other repetitive DNA sequences have been reported in the animal kingdom, studies in the plant kingdom are limited. Here, using FISH, we confirmed that <i>Menolird18</i>, a member of LINE (long interspersed nuclear element) in non-LTR retrotransposons and found in <i>Cucumis melo</i>, was inserted into ITS and ETS (internal and external transcribed spacers) regions of 18S rDNA in melon and cucumber. Beside the 18S rDNA regions, <i>Menolird18</i> was also detected in all centromeric regions of melon, while it was located at pericentromeric and sub-telomeric regions in cucumber. The fact that FISH signals of <i>Menolird18</i> were found in centromeric and rDNA regions of mitotic chromosomes suggests that <i>Menolird18</i> is a rDNA and centromere-specific non-LTR retrotransposon in melon. Our findings are the first report on a non-LTR retrotransposon that is highly conserved in 2 different plant species, melon and cucumber. The clear distinction of chromosomal localization of <i>Menolird18</i> in melon and cucumber implies that it might have been involved in the evolutionary processes of the melon (<i>C. melo</i>) and cucumber (<i>C. sativus</i>) genomes.

scholarly journals Large vs small genomes in Passiflora: the influence of the mobilome and the satellitome

2020 ◽  
Author(s):  
Mariela Sader ◽  
Magdalena Vaio ◽  
Luiz Augusto Cauz-Santos ◽  
Marcelo Carnier Dornelas ◽  
Maria Lucia Carneiro Vieira ◽  
...  
Keyword(s):  
Genome Size ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Large Scale ◽  
Repetitive Sequences ◽  
Size Variation ◽  
Repetitive Dna Sequences ◽  
Ltr Retrotransposons ◽  
Genome Size Variation ◽  
Satellite Dnas

ABSTRACTRepetitive sequences are ubiquitous and fast-evolving elements responsible for size variation and large-scale organization of plant genomes. Within Passiflora genus, a ten-fold variation in genome size, not attributed to polyploidy, is known. Here, we applied a combined in silico and cytological approach to study the organization and diversification of repetitive elements in three species of these genera representing its known range in genome size variation. Sequences were classified in terms of type and repetitiveness and the most abundant were mapped to chromosomes. We identified Long Terminal Repeat (LTR) retrotransposons as the most abundant elements in the three genomes, showing a considerable variation among species. Satellite DNAs (satDNAs) were less representative, but highly diverse between subgenera. Our results clearly confirm that the largest genome species (Passiflora quadrangularis) presents a higher accumulation of repetitive DNA sequences, specially Angela and Tekay elements, making up most of its genome. Passiflora cincinnata, with intermediate genome and from the same subgenus, showed similarity with P. quadrangularis regarding the families of repetitive DNA sequences, but in different proportions. On the other hand, Passiflora organensis, the smallest genome, from a different subgenus, presented greater diversity and the highest proportion of satDNA. Altogether, our data indicate that while large genome evolve by an accumulation of retrotransponsons, small genomes most evolved by diversification of different repeat types, particularly satDNAs.MAIN CONCLUSIONSWhile two lineages of retrotransposons were more abundant in larger Passiflora genomes, the satellitome was more diverse and abundant in the smallest genome.

Quantitative and qualitative genomic characterization of cultivated Ilex L. species

2014 ◽  
Vol 13 (2) ◽  
pp. 142-152 ◽  
Author(s):  
Alexandra Marina Gottlieb ◽  
Lidia Poggio
Keyword(s):  
Genome Size ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Sequence Data ◽  
Repetitive Sequences ◽  
Representational Difference Analysis ◽  
Ilex Paraguariensis ◽  
Repetitive Dna Sequences ◽  
A Genome

The development of modern approaches to the genetic improvement of the tree crops Ilex paraguariensis (‘yerba mate’) and Ilex dumosa (‘yerba señorita’) is halted by the scarcity of basic genetic information. In this study, we characterized the implementation of low-cost methodologies such as representational difference analysis (RDA), single-strand conformation polymorphisms (SSCP), and reverse and direct dot-blot filter hybridization assays coupled with thorough bioinformatic characterization of sequence data for both species. Also, we estimated the genome size of each species using flow cytometry. This study contributes to the better understanding of the genetic differences between two cultivated species, by generating new quantitative and qualitative genome-level data. Using the RDA technique, we isolated a group of non-coding repetitive sequences, tentatively considered as Ilex-specific, which were 1.21- to 39.62-fold more abundant in the genome of I. paraguariensis. Another group of repetitive DNA sequences involved retrotransposons, which appeared 1.41- to 35.77-fold more abundantly in the genome of I. dumosa. The genomic DNA of each species showed different performances in filter hybridizations: while I. paraguariensis showed a high intraspecific affinity, I. dumosa exhibited a higher affinity for the genome of the former species (i.e. interspecific). These differences could be attributed to the occurrence of homologous but slightly divergent repetitive DNA sequences, highly amplified in the genome of I. paraguariensis but not in the genome of I. dumosa. Additionally, our hybridization outcomes suggest that the genomes of both species have less than 80% similarity. Moreover, for the first time, we report herein a genome size estimate of 1670 Mbp for I. paraguariensis and that of 1848 Mbp for I. dumosa.

scholarly journals Repetitive DNA sequences near three humanβ-type globin genes

1980 ◽  
Vol 8 (15) ◽  
pp. 3319-3333 ◽  
Author(s):  
Lesley W. Coggins ◽  
G.Joan Grindlay ◽  
J.Keith Vass ◽  
Alison A. Slater ◽  
Paul Montague ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
Repetitive Dna Sequences ◽  
Globin Genes
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