Elimination of 5S DNA unit classes in newly formed allopolyploids of the genera Aegilops and Triticum

Genome ◽  
2010 ◽  
Vol 53 (6) ◽  
pp. 430-438 ◽  
Author(s):  
B. R. Baum ◽  
M. Feldman
Keyword(s):  
Parental Species ◽  
Chromosome Doubling ◽  
Diploid Species ◽  
Evolutionary Significance ◽  
Intergeneric Hybridization ◽  
Unit Classes ◽  
5S Dna ◽  
The Difference ◽  
Natural And Synthetic

Two classes of 5S DNA units, namely the short (containing units of 410 bp) and the long (containing units of 500 bp), are recognized in species of the wheat (the genera Aegilops and Triticum ) group. While every diploid species of this group contains 2 unit classes, the short and the long, every allopolyploid species contains a smaller number of unit classes than the sum of the unit classes of its parental species. The aim of this study was to determine whether the reduction in these unit classes is due to the process of allopolyploidization, that is, interspecific or intergeneric hybridization followed by chromosome doubling, and whether it occurs during or soon after the formation of the allopolyploids. To study this, the number and types of unit classes were determined in several newly formed allotetraploids, allohexaploids, and an allooctoploid of Aegilops and Triticum. It was found that elimination of unit classes of 5S DNA occurred soon (in the first 3 generations) after the formation of the allopolyploids. This elimination was reproducible, that is, the same unit classes were eliminated in natural and synthetic allopolyploids having the same genomic combinations. No further elimination occurred in the unit classes of the 5S DNA during the life of the allopolyploid. The genetic and evolutionary significance of this elimination as well as the difference in response to allopolyploidization of 5S DNA and rDNA are discussed.

Cytogenetic studies of interspecific hybrids between diploid species of Festuca

1986 ◽  
Vol 28 (6) ◽  
pp. 921-925 ◽  
Author(s):  
W. G. Morgan ◽  
Hugh Thomas ◽  
M. Evans ◽  
M. Borrill
Keyword(s):  
Genome Size ◽  
Chromosome Pairing ◽  
Dna Content ◽  
Interspecific Hybrids ◽  
Parental Species ◽  
Diploid Species ◽  
Chromosome Size ◽  
Cytogenetic Studies ◽  
The Difference

Chromosome pairing in hybrids between diploid species of Festuca is described. The chromosome complements of the species from different taxonomic sections vary in chromosome size and DNA content. In interspecific hybrids involving species of the section Montanae there was a relationship between the difference in DNA content of the parental species and chromosome pairing in the F1 hybrids. The larger the difference between the DNA content of the parental species, the more pronounced the failure of chromosome pairing in the F1 hybrids. Factors other than divergence in genome size were also shown to have an effect on chromosome pairing in other hybrid combinations.Key words: chromosome pairing, DNA content, Festuca, hybrids (interspecific).

scholarly journals Hepatica transsilvanica Fuss (Ranunculaceae) is an Allotetraploid Relict of the Tertiary Flora in Europe – Molecular Phylogenetic Evidence

2020 ◽  
Vol 89 (3) ◽  
Author(s):  
Levente Laczkó ◽  
Gábor Sramkó
Keyword(s):  
Parental Species ◽  
Gene Tree ◽  
Diploid Species ◽  
Nuclear Gene ◽  
Hybrid Origin ◽  
Distribution Area ◽  
Recent Common Ancestor ◽  
Term Survival ◽  
Quaternary Glaciation ◽  
Eastern Carpathians

The <em>Hepatica </em>section <em>Angulosa </em>consists of mainly tetraploid (2<em>n </em>= 28) species that are distributed disjunctly throughout Eurasia. Karyological evidence proves the hybrid origin of the polyploid species of this section. <em>Hepatica transsilvanica </em>is a member of this species group with a conspicuous distribution restricted to the Eastern Carpathians. Based on genome size and cytotypes, the paternal parent of <em>H. transsilvanica </em>is described to be the only diploid species in section <em>Angulosa</em>, <em>H. falconeri</em>. The maternal species is hypothesized to be <em>H. nobilis</em>, a European species with entirely lobed leaves and a wider distribution area. Although the hybrid origin of <em>H. transsilvanica </em>is well documented by karyological evidence, the time of hybridization has never been studied. By using sequences of both the nuclear and plastid genome, we reconstructed the phylogenetic relationships and divergence times of <em>H. transsilvanica </em>and its parental species. The identity of the parental species is corroborated by discordant gene tree topologies of the nrITS and plastid sequences. Moreover, both gene copies of the parental species could be identified with the low-copy nuclear gene, <em>MLH1</em>. Divergence dating analysis using Bayesian phylogenetic methods strongly supported the long-term survival of <em>H. transsilvanica </em>in the Southeastern Carpathians, as the most recent common ancestor of the hybrid and parent species existed not later than the beginning of the Pleistocene, ca. 3 million years ago. These results not only highlight the biogeographic importance of the Southeastern Carpathians in the Quaternary glaciation periods, but also emphasize that Tertiary lineages could have survived in a Central European cryptic refugium.

scholarly journals Relations and evolution in Cheilanthes (Sinopteridaceae, Pteridophita) in Macaronesia and Mediterranean area, deduced from genome analysis of their hybrids

1983 ◽  
Vol 8 ◽  
pp. 101-126 ◽  
Author(s):  
G. Vida ◽  
A. Major ◽  
T. Reichstein
Keyword(s):  
Chromosome Number ◽  
Genome Analysis ◽  
Chromosome Doubling ◽  
Diploid Species ◽  
Mediterranean Area ◽  
Basic Chromosome Number ◽  
The Other ◽  
Experimental Conditions ◽  
Natural Group ◽  
Basic Chromosome

Nine species of "Cheilantoid ferns" are known to grow in Macaronesia and the Mediterranean basin. Two of them (lacking a pseudo-indusium and having the basic chromosome number X = 29), both aggregate species which we prefer to retain in Notholaena, are not included in this study. The other seven species (with distinct pseudo-indusium and the basic chromosome number X = 30), which we accept as members of the genus Cheilanthes Sw. sensu stricto, were subjected to detailed genome analysis of their natural and experimentally produced hybrids and shown to represent an aggregate of four very distinct ancestral diploids and three allotetraploids. The latter must have once been formed by chromosome doubling in the three diploid hybrids of C. maderensis Lowe with the other three diploid species. Theoretically three more allotetraploids would be possible but their formation has obviously been prevented by the geographical separation of the three respective diploids. The most widely distributed of the tetraploids, i.e. C. pteridioides (Reich.) C.Chr. has also been resynthesized from its ancestors (still sympatric) under experimental conditions. The intermediate morphology of the allotetraploids (as compared with their diploid ancestors) is obviously the reason why their status and existence has so long escaped recognition in Europe. These seven species form a natural group and, in our opinion, should not be divided into sections.

Study on the homology of the genomes of tetraploid Asiatic lilies (Lilium) using FISH

Genome ◽  
2015 ◽  
Vol 58 (11) ◽  
pp. 453-461 ◽  
Author(s):  
Shujun Zhou ◽  
Lei Zhong ◽  
Lu Zhang ◽  
Zhenghua Xu ◽  
Xuxin Liu ◽  
...  
Keyword(s):  
Chromosome Doubling ◽  
Pollen Viability ◽  
Diploid Species ◽  
45S Rdna ◽  
Chromosomal Association

Asiatic lily cultivars, bred by hybridization and (or) chromosome doubling of species of section Sinomartagon of Lilium, are diploid, triploid, or tetraploid, but the homology of the genomes among species of section Sinomartagon and Asiatic lilies remains unclear. In the present research, two tetraploid Asiatic cultivars were analyzed, using 45S rDNA as probe, for their FISH karyotypes and their chromosomal association, anaphase I, telophase II, and pollen viability were surveyed to assess the multivalent segregation. Chromosomal assortment of six progenies of the two tetraploid cultivars were also investigated. The results showed that the tetraploid cultivars had similar FISH karyotypes, they predominantly formed multivalents, and these were equally separated because their anaphase I, telophase II, and pollen viability were similar to those of diploid species. Apart from minor variations, FISH karyotypes of progenies were similar to each other and to their parents. Based on these results and considering the high crossability among species of section Sinomartagon and (or) Asiatic lilies, we concluded that species of section Sinomartagon and their resulting cultivars share a common genome; thus, polyploidy Asiatic lilies are autopolyploid.

Diallel analysis of competition between diploid and tetraploid genotypes of Secale cereale grown at two densities

1972 ◽  
Vol 78 (2) ◽  
pp. 251-256 ◽  
Author(s):  
J. Norrington-Davies ◽  
Janice M. Hutto
Keyword(s):  
Secale Cereale ◽  
Competitive Ability ◽  
Chromosome Doubling ◽  
Diallel Analysis ◽  
Dry Weight ◽  
Inbred Lines ◽  
Pure Stand ◽  
Competitive Effects ◽  
Alpha Effect ◽  
The Difference

SUMMARYTwo inbred diploid lines of Secale cereale L. and their derived tetraploids were grown together with a commercial diploid and tetraploid in all possible pair combinations in a pot experiment. Comparisons between lines and varieties were made in respect to dry weight measured at 30 weeks.The competitive effects within mixtures were not compensatory, the commercial varieties tending to increase in dry weight more than the homozygous inbred lines decreased. This gave rise to mixture means which tended to exceed their mid-constituent values.The analysis of reciprocal differences in dry weight showed that the effects of competition between any one genotype and its associate in mixtures were constant (alpha competition), the sign and magnitude of the alpha effect being related to the pure stand values of the genotype.The mean effect of competition was to increase the difference in dry weight between genotypes by 2·108 g for each gram by which the genotypes differed when grown alone. In each case the values for genotypes with the higher dry weight increased in mixture whereas the values for those with lower dry weights decreased.Not surprisingly, the commercial varieties were found to be better competitors than the inbred lines, but of more interest was the ineffectiveness of chromosome doubling on competitive ability. Under the conditions of density and fertility reported here, the tetraploid inbred lines could not be distinguished from their diploid progenitors either in their competitive ability or in their reaction to increased density when grown in mixtures. The same is true for the tetraploid and diploid commercial varieties.

Triploidy and its evolutionary significance in Cystopteris protrusa

1985 ◽  
Vol 63 (10) ◽  
pp. 1855-1863 ◽  
Author(s):  
Christopher H. Haufler ◽  
Michael D. Windham ◽  
Donald M. Britton ◽  
Scott J. Robinson
Keyword(s):  
Environmental Stress ◽  
Diploid Species ◽  
Intermediate Stage ◽  
Evolutionary Significance ◽  
Polyploid Formation ◽  
Homosporous Ferns ◽  
Diploid Gametes ◽  
Diploid Populations

The most widely recognized mode of polyploid formation in homosporous ferns is allopolyploidy. There are taxa, however, that appear to have arisen through autopolyploidy. Several widely separated collections of the normally diploid species Cystopteris protrusa were found to be triploid. Plants in these collections were morphologically similar to typical, diploid C. protrusa, exhibited a significant number of trivalents during meiosis, and corresponded allozymically to heterozygotes from diploid populations. These plants probably arose through outcrossing between normal, haploid gametes and unreduced, diploid gametes. It is hypothesized that this mechanism of autopolyploid formation is stimulated by environmental stress and may be an intermediate stage in the formation of sexually reproductive tetraploids.

Dilemma of genome relationship in the diploid species Thinopyrum bessarabicum and Thinopyrum elongatum (Triticeae: Poaceae)

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 944-946 ◽  
Author(s):  
Prem P. Jauhar
Keyword(s):  
Chromosome Pairing ◽  
Constitutive Heterochromatin ◽  
Diploid Species ◽  
Total Content ◽  
Ploidy Levels ◽  
5S Dna ◽  
Thinopyrum Bessarabicum ◽  
Thinopyrum Elongatum ◽  
Relationship Of ◽  
The Relationship

Evidence on the relationship of the J genome of diploid Thinopyrum bessarabicum and the E genome of diploid Thinopyrum elongatum (= Lophopyrum elongatum) is discussed. Low chromosome pairing between J and E at different ploidy levels, suppression of J–E pairing by the Ph1 pairing regulator that inhibits homoeologous pairing, complete sterility of the diploid hybrids (JE), karyotypic differentiation of the two genomes and differences in their biochemical organization as reflected in total content and distribution of constitutive heterochromatin, and marked differences in isozymes, 5S DNA, and rDNA indicate that J and E are distinct genomes. These genomes are homoeologous and not homologous. There is no justification for the merger of J and E genomes.Key words: chromosome pairing, Ph1 pairing regulator, C-banding, isozymes, 5S DNA, rDNA.

A comparison of the 5S rDNA diversity in the Hordeum brachyantherum–californicum complex with those of the eastern Asiatic Hordeum roshevitzii and the South American Hordeum cordobense (Triticeae: Poaceae)

2002 ◽  
Vol 80 (7) ◽  
pp. 752-762 ◽  
Author(s):  
Bernard R Baum ◽  
Douglas A Johnson
Keyword(s):  
Species Recognition ◽  
Cladistic Analysis ◽  
Strong Support ◽  
5S Rdna ◽  
Hordeum Spontaneum ◽  
Consensus Sequences ◽  
Rdna Sequences ◽  
Unit Classes ◽  
Unit Class ◽  
5S Dna

Amplification of the 5S rDNA gene by the polymerase chain reaction, followed by cloning and sequencing, was used to generate data from 23 seed accessions of Hordeum brachyantherum Nevski, Hordeum californicum Covas et Stebbins, Hordeum cordobense Bothmer, Jacobsen et Nicora, and Hordeum roshevitzii Bowden. One hundred and fourteen clones were analyzed, resulting in the detection of four different 5S DNA unit classes. Three of them, long H1, long H2, and long Y2, had been previously reported. The long H3 class, described for the first time, is present only in H. roshevitzii but can be grouped with previously unassigned units of Hordeum bulbosum L. and Hordeum spontaneum C. Koch. Based upon the analyses of 5S rDNA sequences, we found that (i) the long H2 unit class was not found in the Asiatic H. roshevitzii and therefore may be restricted to the American species, (ii) there is no strong support that H. brachyantherum and H. californicum are worthy of species recognition, and (iii) cladistic analysis of the consensus sequences of the four paralogous unit classes demonstrated that long Y2 is the most distant from the three long H classes.Key words: 5S DNA gene, Hordeum, unit classes.

scholarly journals Morphological description of a novel synthetic allotetraploid(A1A1G3G3) of Gossypium herbaceum L.and G.nelsonii Fryx. suitable for disease-resistant breeding applications

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0242620
Author(s):  
Xiaomin Yin ◽  
Rulin Zhan ◽  
Yingdui He ◽  
Shun Song ◽  
Lixia Wang ◽  
...  
Keyword(s):  
Chromosome Doubling ◽  
Diploid Species ◽  
Morphological Description ◽  
Tetraploid Cotton ◽  
Distant Hybridization ◽  
Cotton Species ◽  
Cotton Plants ◽  
Wild Cotton ◽  
Diploid Cotton ◽  
Gossypium Herbaceum

Wild species of Gossypium ssp. are an important source of traits for improving commercial cotton cultivars. Previous reports show that Gossypium herbaceum L. and Gossypium nelsonii Fryx. have better disease resistance characteristics than commercial cotton varieties. However, chromosome ploidy and biological isolation make it difficult to hybridize diploid species with the tetraploid Gossypium hirsutum L. We developed a new allotetraploid cotton genotype (A1A1G3G3) using a process of distant hybridization within wild cotton species to create new germplasms. First of all, G. herbaceum and G. nelsonii were used for interspecific hybridization to obtain F1 generation. Afterwards, apical meristems of the F1 diploid cotton plants were treated with colchicine to induce chromosome doubling. The new interspecific F1 hybrid and S1 cotton plants originated from chromosome duplication, were tested via morphological and molecular markers and confirmed their tetraploidy through flowrometric and cytological identification. The S1 tetraploid cotton plants was crossed with a TM-1 line and fertile hybrid offspring were obtained. These S2 offsprings were tested for resistance to Verticillium wilt and demonstrated adequate tolerance to this fungi. The results shows that the new S1 cotton line could be used as parental material for hybridization with G. hirsutum to produce pathogen-resistant cotton hybrids. This new S1 allotetraploid genotype will contributes to the enrichment of Gossypium germplasm resources and is expected to be valuable in polyploidy evolutionary studies.

scholarly journals Homeolog expression quantification methods for allopolyploids

2018 ◽  
Vol 21 (2) ◽  
pp. 395-407 ◽  
Author(s):  
Tony C Y Kuo ◽  
Masaomi Hatakeyama ◽  
Toshiaki Tameshige ◽  
Kentaro K Shimizu ◽  
Jun Sese
Keyword(s):  
Sequence Similarity ◽  
Diploid Species ◽  
Ground Truth ◽  
Error Rates ◽  
Rna Seq ◽  
Gene Copies ◽  
The Difference ◽  
Downstream Analysis ◽  
High Level ◽  
Expression Quantification

Abstract Genome duplication with hybridization, or allopolyploidization, occurs in animals, fungi and plants, and is especially common in crop plants. There is an increasing interest in the study of allopolyploids because of advances in polyploid genome assembly; however, the high level of sequence similarity in duplicated gene copies (homeologs) poses many challenges. Here we compared standard RNA-seq expression quantification approaches used currently for diploid species against subgenome-classification approaches which maps reads to each subgenome separately. We examined mapping error using our previous and new RNA-seq data in which a subgenome is experimentally added (synthetic allotetraploid Arabidopsis kamchatica) or reduced (allohexaploid wheat Triticum aestivum versus extracted allotetraploid) as ground truth. The error rates in the two species were very similar. The standard approaches showed higher error rates (&gt;10% using pseudo-alignment with Kallisto) while subgenome-classification approaches showed much lower error rates (&lt;1% using EAGLE-RC, &lt;2% using HomeoRoq). Although downstream analysis may partly mitigate mapping errors, the difference in methods was substantial in hexaploid wheat, where Kallisto appeared to have systematic differences relative to other methods. Only approximately half of the differentially expressed homeologs detected using Kallisto overlapped with those by any other method in wheat. In general, disagreement in low-expression genes was responsible for most of the discordance between methods, which is consistent with known biases in Kallisto. We also observed that there exist uncertainties in genome sequences and annotation which can affect each method differently. Overall, subgenome-classification approaches tend to perform better than standard approaches with EAGLE-RC having the highest precision.

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