Karyological analysis and genome size in Milium (Gramineae) with special reference to polyploidy and chromosomal evolution

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 868-878 ◽  
Author(s):  
Simon T. Bennett ◽  
Sandra M. Thomas
Keyword(s):  
Genome Size ◽  
Geographical Distribution ◽  
Dna Sequences ◽  
Chromosome Evolution ◽  
Nuclear Dna ◽  
Chromosomal Evolution ◽  
System Support ◽  
Strong Resemblance ◽  
First Time ◽  
Dna Amounts

Karyotypes, nuclear DNA amounts, and meiotic behaviour are presented for Milium effusum L. (2n = 28), Milium montianum Parl. (2n = 22), and two cytotypes of Milium vernale Bieb. (2n = 8, 10). The bimodal karyotype of M. montianum (8 large and 14 small chromosomes) is described for the first time. Evidence from C-banding and geographical distribution suggests an ancient interracial allopolyploid origin for M. effusum (2n = 28). Although M. montianum is undoubtedly allopolyploid, its parentage is unconfirmed. A strong resemblance between the M. vernale (2n = 8) karyotype and the eight large chromosomes in M. montianum suggests a common ancestry. It is possible that a diploid form of M. effusum contributed the remaining 14 chromosomes. A selective loss of DNA sequences from the smaller chromosomes during the subsequent reorganization of the allopolyploid genome may have enhanced the bimodality of the karyotype. Geographical distribution and a change in the breeding system support the direction of the change x = 5 to x = 4 in M. vernale. Allopolyploidy appears to have played a central role in the chromosome evolution and speciation of Milium.Key words: Milium (Gramineae), karyotype analysis, genome size, polyploidy, chromosome evolution.

Nuclear DNA amount and genome downsizing in natural and synthetic allopolyploids of the genera Aegilops and Triticum

Genome ◽  
2008 ◽  
Vol 51 (8) ◽  
pp. 616-627 ◽  
Author(s):  
T. Eilam ◽  
Y. Anikster ◽  
E. Millet ◽  
J. Manisterski ◽  
M. Feldman
Keyword(s):  
Genome Size ◽  
Dna Sequences ◽  
First Generation ◽  
Nuclear Dna ◽  
Chromosome Doubling ◽  
Intergeneric Hybridization ◽  
Dna Amount ◽  
B Genome ◽  
Nuclear Dna Amount ◽  
Dna Amounts

Recent molecular studies in the genera Aegilops and Triticum showed that allopolyploidization (interspecific or intergeneric hybridization followed by chromosome doubling) generated rapid elimination of low-copy or high-copy, non-coding and coding DNA sequences. The aims of this work were to determine the amount of nuclear DNA in allopolyploid species of the group and to see to what extent elimination of DNA sequences affected genome size. Nuclear DNA amount was determined by the flow cytometry method in 27 natural allopolyploid species (most of which were represented by several lines and each line by several plants) as well as 14 newly synthesized allopolyploids (each represented by several plants) and their parental plants. Very small intraspecific variation in DNA amount was found between lines of allopolyploid species collected from different habitats or between wild and domesticated forms of allopolyploid wheat. In contrast to the constancy in nuclear DNA amount at the intraspecific level, there are significant differences in genome size between the various allopolyploid species, at both the tetraploid and hexaploid levels. In most allopolyploids nuclear DNA amount was significantly less than the sum of DNA amounts of the parental species. Newly synthesized allopolyploids exhibited a similar decrease in nuclear DNA amount in the first generation, indicating that genome downsizing occurs during and (or) immediately after the formation of the allopolyploids and that there are no further changes in genome size during the life of the allopolyploids. Phylogenetic considerations of the origin of the B genome of allopolyploid wheat, based on nuclear DNA amount, are discussed.

Associated chromosomal DNA changes in polyploids

Genome ◽  
1994 ◽  
Vol 37 (4) ◽  
pp. 560-564 ◽  
Author(s):  
S. N. Raina ◽  
A. Parida ◽  
K. K. Koul ◽  
S. S. Salimath ◽  
M. S. Bisht ◽  
...  
Keyword(s):  
Genome Size ◽  
Dna Content ◽  
Nuclear Dna ◽  
Seed Set ◽  
Diploid Species ◽  
Expected Value ◽  
Chromosomal Dna ◽  
Seed Fertility ◽  
Dna Loss ◽  
Dna Amounts

The 2C and 4C nuclear DNA amounts were estimated in eight diploid species, belonging to three diverse genera (Vicia, Tephrosia, and Phlox) and their corresponding colchitetraploids. In P. drummondii, T. purpurea, and T. oxygona tetraploids the deviation from the expectation was highly significant. The DNA in P. drummondii was further discarded in subsequent (C1, C2) generations, thus attaining an overall reduction of about 25%. The DNA content in the subsequent generations was the same as that of C2. It is concluded that rapid DNA loss in the first and subsequent generations was not only associated with the substantial increase (30–66%) in the seed set, but it also helped in the establishment and stabilization of the tetraploid. The possible relationship between such a nucleotypic change and success of polyploids is discussed. The DNA change from the expected value in the P. drummondii tetraploid was achieved by equal decrement to each chromosome independent of size, i.e., small chromosomes loose the same amount of DNA as the large chromosomes.Key words: colchitetraploid, genome size, DNA loss, seed fertility, stability, DNA distribution.

Genome size in natural and synthetic autopolyploids and in a natural segmental allopolyploid of several Triticeae species

Genome ◽  
2009 ◽  
Vol 52 (3) ◽  
pp. 275-285 ◽  
Author(s):  
T. Eilam ◽  
Y. Anikster ◽  
E. Millet ◽  
J. Manisterski ◽  
M. Feldman
Keyword(s):  
Genome Size ◽  
Dna Sequences ◽  
Nuclear Dna ◽  
Reduction Process ◽  
Distribution Area ◽  
Meiotic Pairing ◽  
Dna Amount ◽  
Similar Reduction ◽  
Nuclear Dna Amount ◽  
Hordeum Murinum

Nuclear DNA amount (1C) was determined by flow cytometry in the autotetraploid cytotype of Hordeum bulbosum , in the cytologically diploidized autotetraploid cytotypes of Elymus elongatus , Hordeum murinum subsp. murinum and Hordeum murinum subsp. leporinum, in Hordeum marinum subsp. gussoneanum, in their progenitor diploid cytotypes, and in a newly synthesized autotetraploid line of E. elongatus. Several lines collected from different regions of the distribution area of every taxon, each represented by a number of plants, were analyzed in each taxon. The intracytotype variation in nuclear DNA amount of every diploid and autotetraploid cytotype was very small, indicating that no significant changes have occurred in DNA amount either after speciation or after autopolyploid formation. The autotetraploid cytotypes of H. bulbosum and the cytologically diploidized H. marinum subsp. gussoneanum had the expected additive amount of their diploid cytotypes. On the other hand, the cytologically diploidized autotetraploid cytotypes of E. elongatus and H. murinum subsp. murinum and H. murinum subsp. leporinum had considerably less nuclear DNA (10%–23%) than the expected additive value. Also, the newly synthesized autotetraploid line of E. elongatus showed similar reduction in DNA as its natural counterpart, indicating that the reduction in genome size occurred in the natural cytotype during autopolyploidization. It is suggested that the diploid-like meiotic behavior of these cytologically dipolidized autotetraploids is caused by the instantaneous elimination of a large number of DNA sequences, different sequences from different homologous pairs, leading to differentiation of the constituent genomes. The eliminated sequences are likely to include those that participate in homologous recognition and initiation of meiotic pairing. A gene system determining exclusive bivalent pairing by utilizing the differentiation between the two groups of homologues has been presumably superimposed on the DNA reduction process.

The roles of possible geographic barriers and geological events on the phylogeographic structure of the Eastern broad toothed field mouse (Apodemus mystacinus)

Mammalia ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gül Olgun Karacan ◽  
Reyhan Çolak ◽  
Ercüment Çolak
Keyword(s):  
Dna Sequences ◽  
Nuclear Dna ◽  
Phylogeographic Structure ◽  
Field Mouse ◽  
Interphotoreceptor Retinoid Binding Protein ◽  
Aegean Islands ◽  
Mitochondrial Data ◽  
D Loop ◽  
Physical Barriers ◽  
First Time

Abstract The Eastern broad toothed field mouse, Apodemus mystacinus, is a rodent species distributed in Turkey, the Middle East, and a few Aegean Islands. The aim of this study is to analyse the phylogeographic structure of A. mystacinus and possible causes of its differentiation, on the basis of mitochondrial and nuclear DNA sequences using a large number of new samples from Turkey. In this context, partial mitochondrial sequences of cytochrome b (Cytb), control region (D-loop) and a nuclear interphotoreceptor retinoid-binding protein (IRBP) gene were used to reveal the geographical differentiation among A. mystacinus populations and the validity of its subspecies. The estimated divergence times revealed that the first separation of A. mystacinus into three distinct groups (subspecies of A. mystacinus: A. m. mystacinus, A. m. smyrnensis, and A. m. euxinus) begun 0.641 Mya. The possible physical barriers in Anatolia such as high mountains and rivers could interrupt the gene flow between A. mystacinus populations. The results of the present study indicated that A. mystacinus might have used the high rocky areas along the Anatolian Diagonal as a dispersal way. Moreover, mitochondrial data in this study suggested for the first time that A. m. rhodius is synonymous with the nominative subspecies A. m. mystacinus.

CYTOGENETICS OF CHILEAN FISHES: A COMMENTED DATABASE

2020 ◽  
Vol 4 (13-16) ◽  
Author(s):  
Pedro Jara-Seguel ◽  
Gladys Lara ◽  
María Paz García ◽  
Iván Valdebenito
Keyword(s):  
Chromosome Number ◽  
Genome Size ◽  
Fish Species ◽  
Dna Sequences ◽  
Fish Diversity ◽  
Cytogenetic Data ◽  
Cytogenetic Studies ◽  
Karyotype Morphology ◽  
First Time ◽  
Cytogenetic Methods

<p>A database containing data from cytogenetic studies of Chilean fish species is documented for the first time. The cytogenetic data compiled for Chilean fishes include 28 species belonging to 11 families, 9 orders and 16 genera, taking as reference 18 publications since 1972. The application of a variety of cytogenetic methods has provided information on chromosome number, karyotype morphology, genome size, and /or location of different DNA sequences. These data represent only ca. 2.7% of Chile’s fish diversity.</p>

Peaceful revolution in genome size: polyploidy in the Nabidae (Heteroptera); autosomes and nuclear DNA content doubling

2020 ◽  
Author(s):  
David Sadílek ◽  
Jitka Vilímová ◽  
Tomáš Urfus
Keyword(s):  
Genome Size ◽  
X Chromosome ◽  
Dna Content ◽  
18S Rdna ◽  
Nuclear Dna ◽  
Nuclear Dna Content ◽  
Chromosome Breakage ◽  
Polyploidy Event ◽  
First Time

Abstract Genome size and the position of 18S ribosomal DNA (rDNA) were analysed in two Himacerus, eight Nabis and two Prostemma species from the family Nabidae using flow cytometry and fluorescence in situ hybrization techniques. The karyotypes of Nabis biformis and Nabis maoricus, each with 2n = 16 + XY, and Prostemma aeneicolle, with 2n = 26 + XY, were recorded for the first time. All the species displayed one or two 18S rDNA signals on the X chromosome and up to two signals on the Y chromosome. Several females exhibited two different types of X chromosome breakage, namely within or outside of the 18S rDNA region. Measurements of nuclear DNA content revealed significant differences between all three genera under study. Most notably, the nuclear DNA content of Himacerus species, with 2n = 32/36 + XY (2C = 9–10 pg), was double that of Nabis species, with 2n = 16 + XY (2C = 4–6 pg). Therefore, the previously rejected theory of an autosomal polyploidy event in the evolution of the genus Himacerus is strongly supported by the results of the present study and is now being resurrected.

Nuclear DNA amounts in angiosperms

1991 ◽  
Vol 334 (1271) ◽  
pp. 309-345 ◽  
Keyword(s):  
Genome Size ◽  
Nuclear Dna ◽  
Nuclear Genome ◽  
Flowering Plant ◽  
Alphabetical Order ◽  
Additional Information ◽  
Supplementary List ◽  
Angiosperm Species ◽  
The Many ◽  
Dna Amounts

Collected lists of nuclear DNA amounts estimated for a total of almost 1000 angiosperm species were published by Bennett & Smith ( Phil. Trans. R. Soc. Lond. B 274, 227—274 (1976)), and by Bennett et al . ( Proc. R. Soc. Lond . B 216, 179-199 (1982 a )). Subsequently, work on nuclear genome size in flowering plant taxa, and interest in its consequences, has increased. Thus, estimates for 588 angiosperm species not previously listed were published, or communicated to us, between 1982 and mid-1986. As these additional estimates came from more than 50 sources which were either widely scattered in the scientific literature or unpublished personal communications, they are not readily accessible. This, and the many personal enquiries for the information received, shows that a further publication, compiling the new data is needed. This paper, therefore, contains a further supplementary list of absolute DNA amounts. This new compilation includes DNA C values for 629 angiosperm species not listed in either of the above-mentioned papers, with additional estimates for 119 species already listed by them. These data are assembled primarily for reference purposes. Analysis of citations of the two previously published lists and of personal requests for additional information both show that the major users of genome size information are cell and molecular biologists. Consequently, the species are listed as before in alphabetical order, rather than by any taxonomic scheme, as this was felt to be more helpful to these users

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.

Variation in chromosomal DNA associated with the evolution of Arachis species

Genome ◽  
1996 ◽  
Vol 39 (5) ◽  
pp. 890-897 ◽  
Author(s):  
K. P. Singh ◽  
S. N. Raina ◽  
A. K. Singh
Keyword(s):  
Genome Size ◽  
Arachis Hypogaea ◽  
Intraspecific Variation ◽  
Dna Content ◽  
Nuclear Dna ◽  
Mean Value ◽  
Chromosomal Dna ◽  
Arachis Species ◽  
Arachis Duranensis ◽  
Dna Amounts

The 2C nuclear DNA amounts were determined for 99 accessions, representing 23 Arachis species from 8 of 9 taxonomic sections, and two synthetic amphidiploids. Mean 2C DNA amounts varied by 15.20%, ranging from 10.26 to 11.82 pg, between accessions of Arachis hypogaea (2n = 4x = 40). Nuclear DNA content variation (5.33–5.91 pg) was also detected among Arachis duranensis (2n = 2x = 20) accessions. The intraspecific variation in the two species may have resulted from indirect selection for favourable genome sizes in particular environmental conditions. The accessions belonging to A. hypogaea ssp. hypogaea (mean value 11.27 pg) with longer life cycle had significantly larger mean DNA content than the accessions of A. hypogaea ssp. fastigiata (mean value 10.97 pg). For 20 diploid (2n = 2x = 20) species of the genus, 2C nuclear DNA amounts ranged from approximately 3 to 7 pg. The diploid perennial species of section Arachis have about 12% more DNA than the annual species. Comparisons of DNA amounts show that evolutionary rating is not a reliable guide to DNA amounts in generic sections of the genus; lower DNA values with evolutionary advancement were found in sections Heteranthae and Triseminatae, but the same was not true for sections Arachis and Caulorrhizae. Similarly, there is evidence of significant differences in DNA content between 4 ancient sections (Procumbentes, Erectoides, Rhizomatosae, and Extranervosae) of the genus. The occurrence of genome size plasticity in both A. duranensis and A. hypogaea provides evidence that A. duranensis could be one of the diploid progenitors of A. hypogaea. The DNA content in the two synthetic amphidiploids corresponded to the sum value estimated for parental species. Key words : Arachis species, genome size, Arachis hypogaea, Arachis duranensis, intraspecific variation.

scholarly journals Quantum patterns of genome size variation in angiosperms

2020 ◽  
Vol 15 ◽  
Author(s):  
Liaofu Luo ◽  
Lirong Zhang
Keyword(s):  
Genome Evolution ◽  
Genome Size ◽  
Evolution Operator ◽  
Nuclear Dna ◽  
Size Variation ◽  
Dna Amount ◽  
Genome Size Variation ◽  
A Genome ◽  
Eigen Value ◽  
Dna Amounts

Aims: The discontinuous pattern of genome size variation in angiosperms is an unsolved problem related to genome evolution. We introduce a genome evolution operator and solve the related eigen-value equation to deduce the discontinuous pattern. Background: Genome is a well-defined system for studying evolution of species. One of the basic problems is the genome size evolution. The DNA amounts for angiosperm species are highly variable differing over 1000-fold. One big surprise is the discovery of the discontinuous distribution of nuclear DNA amounts in many angiosperm genera. Objective: The discontinuous distribution of nuclear DNA amounts have certain regularity much like a group of quantum states in atomic physics. The quantum pattern has not been explained by all the evolutionary theories so far and we shall interpret it through the quantum simulation of genome evolution. Methods: We have introduced a genome evolution operator H to deduce the distribution of DNA amount. The nuclear DNA amount in angiosperms is studied from the eigen-value equation of the genome evolution operator H. The operator H is introduced by physical simulation and it is defined as a function of the genome size N and the derivative with respective to the size. Results: The discontinuity of DNA size distribution and its synergetic occurrence in related angiosperms species are successfully deduced from the solution of the equation. The results agree well with the existing experimental data of Aloe, Clarkia, Nicotiana, Lathyrus, Allium and other genera. Conclusion: The success of our approach may infer the existence of a set of genomic evolutionary equations satisfying classical – quantum duality. The classical phase of evolution means it obeying classical deterministic law, while the quantum phase means it obeying quantum stochastic law. The discontinuity of DNA size distribution provides fresh evidence on the quantum evolution of angiosperms. People realize that the discontinuous pattern is due to the existence of some unknown evolutionary constrains. However, our study indicates that these constrains on angiosperm genome are essentially of quantum origin.

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