scholarly journals Polyspermy in angiosperms: Its contribution to polyploid formation and speciation

2020 ◽  
Vol 87 (3) ◽  
pp. 374-379 ◽  
Author(s):  
Erika Toda ◽  
Takashi Okamoto
Keyword(s):  
Polyploid Formation

scholarly journals Ploidy frequencies in plants with ploidy heterogeneity: fitting a general gametic model to empirical population data

2013 ◽  
Vol 280 (1751) ◽  
pp. 20122387 ◽  
Author(s):  
Jan Suda ◽  
Tomáš Herben
Keyword(s):  
Natural Populations ◽  
Evolutionary Process ◽  
Optimization Procedure ◽  
Population Data ◽  
Unreduced Gametes ◽  
Unreduced Gamete ◽  
Model Parameters ◽  
Main Mode ◽  
Ploidy Levels ◽  
Polyploid Formation

Genome duplication (polyploidy) is a recurrent evolutionary process in plants, often conferring instant reproductive isolation and thus potentially leading to speciation. Outcome of the process is often seen in the field as different cytotypes co-occur in many plant populations. Failure of meiotic reduction during gametogenesis is widely acknowledged to be the main mode of polyploid formation. To get insight into its role in the dynamics of polyploidy generation under natural conditions, and coexistence of several ploidy levels, we developed a general gametic model for diploid–polyploid systems. This model predicts equilibrium ploidy frequencies as functions of several parameters, namely the unreduced gamete proportions and fertilities of higher ploidy plants. We used data on field ploidy frequencies for 39 presumably autopolyploid plant species/populations to infer numerical values of the model parameters (either analytically or using an optimization procedure). With the exception of a few species, the model fit was very high. The estimated proportions of unreduced gametes (median of 0.0089) matched published estimates well. Our results imply that conditions for cytotype coexistence in natural populations are likely to be less restrictive than previously assumed. In addition, rather simple models show sufficiently rich behaviour to explain the prevalence of polyploids among flowering plants.

scholarly journals Polyploid Formation via Chromosome Duplication Induced by CTP:Phosphocholine Cytidylyltransferase Deficiency and Bcl-2 Overexpression: Identification of Two Novel Endogenous Factors

2005 ◽  
Vol 53 (6) ◽  
pp. 725-733 ◽  
Author(s):  
You-Jun Shen ◽  
Cynthia J. DeLong ◽  
Francois Tercé ◽  
Timothy Kute ◽  
Mark C. Willingham ◽  
...  
Keyword(s):  
Dna Content ◽  
Chinese Hamster ◽  
B Cell Lymphoma ◽  
Negative Regulator ◽  
Ovary Cell ◽  
Endogenous Factors ◽  
Ctp:Phosphocholine Cytidylyltransferase ◽  
Polyploid Formation ◽  
Cellular Dna ◽  
Diploid Cells

Polyploidy is a profound phenotype found in tumors and its mechanism is unknown. We report here that when B-cell lymphoma gene-2 (Bcl-2) was overexpressed in a Chinese hamster ovary cell line that was deficient in CTP:phosphocholine cytidylyltransferase (CT), cellular DNA content doubled. The higher DNA content was due to a permanent conversion from diploid cells to tetraploid cells. The mechanism of polyploid formation could be attributed to the duplication of 18 parental chromosomes. The rate of conversion from diploid to tetraploid was Bcl-2 dose dependent. The diploid genome was not affected by Bcl-2 expression or by CT deficiency alone. Endogenous CT or expression of recombinant rat liver CTα prior to Bcl-2 expression prevented the formation of polyploid cells. This conversion was irreversible even when both initiating factors were removed. In this study, we have identified Bcl-2 as a positive regulator and CTα as a negative regulator of polyploid formation.

scholarly journals Polyploid Formation Shapes Flowering Plant Diversity

2014 ◽  
Vol 184 (4) ◽  
pp. 456-465 ◽  
Author(s):  
Samuel V. Scarpino ◽  
Donald A. Levin ◽  
Lauren Ancel Meyers
Keyword(s):  
Plant Diversity ◽  
Flowering Plant ◽  
Polyploid Formation

scholarly journals Duplicated genes evolve independently after polyploid formation in cotton

1999 ◽  
Vol 96 (25) ◽  
pp. 14406-14411 ◽  
Author(s):  
R. C. Cronn ◽  
R. L. Small ◽  
J. F. Wendel
Keyword(s):  
Duplicated Genes ◽  
Polyploid Formation

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.

scholarly journals Analysis of small RNA changes in different Brassica napus synthetic allopolyploids

2019 ◽  
Author(s):  
Yunxiao Wei ◽  
Fei Li ◽  
Shujiang Zhang ◽  
Shifan Zhang ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Differential Expression ◽  
Small Rna ◽  
Target Genes ◽  
Enrichment Analysis ◽  
Small Rna Sequencing ◽  
Go Enrichment ◽  
Polyploid Formation ◽  
Differentially Expressed Mirnas ◽  
New Perspective ◽  
Go Enrichment Analysis

Allopolyploidy is an evolutionary and mechanisticaly intriguing process involving the reconciliation of two or more sets of diverged genomes and regulatory interactions, resulting in new phenotypes. In this study, we explored the small RNA changes of eight F2 synthetic B. napus using small RNA sequencing. We found that a part of miRNAs and siRNAs were non-additively expressed in the synthesized B. napus allotetraploid. Differentially expressed miRNAs and siRNAs differed among eight F2 individuals, and the differential expression of miR159 and miR172 was consistent with that of flowering time trait. The GO enrichment analysis of differential expression miRNA target genes found that most of them were concentrated in ATP-related pathways, which might be a potential regulatory process contributing to heterosis. In addition, the number of siRNAs present in the offspring was significantly higher than that of the parent, and the number of high parents was significantly higher than the number of low parents. The results have shown that the differential expression of miRNA lays the foundation for solving the trait separation phenomenon, and the significant increase of siRNA alleviates the shock of the newly synthesized allopolyploidy. It provides a new perspective of small RNA changes and trait separation in the early stages of allopolyploid polyploid formation.

scholarly journals Phylogenomics reveals an extensive history of genome duplication in diatoms (Bacillariophyta)

2017 ◽  
Author(s):  
Matthew Parks ◽  
Teofil Nakov ◽  
Elizabeth Ruck ◽  
Norman J. Wickett ◽  
Andrew J. Alverson
Keyword(s):  
Whole Genome Duplication ◽  
Large Scale ◽  
Genome Duplication ◽  
Gene Tree ◽  
Genomic Diversity ◽  
Phylogenomic Analysis ◽  
Whole Genome ◽  
Gene Trees ◽  
Angiosperm Evolution ◽  
Polyploid Formation

ABSTRACTPremise of the studyDiatoms are one of the most species-rich lineages of microbial eukaryotes. Similarities in clade age, species richness, and contributions to primary production motivate comparisons to flowering plants, whose genomes have been inordinately shaped by whole genome duplication (WGD). These events that have been linked to speciation and increased rates of lineage diversification, identifying WGDs as a principal driver of angiosperm evolution. We synthesized a relatively large but scattered body of evidence that, taken together, suggests that polyploidy may be common in diatoms.MethodsWe used data from gene counts, gene trees, and patterns of synonymous divergence to carry out the first large-scale phylogenomic analysis of genome-scale duplication histories for a phylogenetically diverse set of 37 diatom taxa.Key resultsSeveral methods identified WGD events of varying age across diatoms, though determining the exact number and placement of events and, more broadly, inferences of WGD at all, were greatly impacted by gene-tree uncertainty. Gene-tree reconciliations supported allopolyploidy as the predominant mode of polyploid formation, with particularly strong evidence for ancient allopolyploid events in the thalassiosiroid and pennate diatom clades.ConclusionsWhole genome duplication appears to have been an important driver of genome evolution in diatoms. Denser taxon sampling will better pinpoint the timing of WGDs and likely reveal many more of them. We outline potential challenges in reconstructing paleopolyploid events in diatoms that, together with these results, offer a framework for understanding the evolutionary roles of genome duplication in a group that likely harbors substantial genomic diversity.

Development of polyspermic zygote and possible contribution of polyspermy to polyploid formation in angiosperms

2017 ◽  
Vol 130 (3) ◽  
pp. 485-490 ◽  
Author(s):  
Takashi Okamoto ◽  
Yukinosuke Ohnishi ◽  
Erika Toda
Keyword(s):  
Polyploid Formation

scholarly journals Polyploid formation in cotton is not accompanied by rapid genomic changes

Genome ◽  
2001 ◽  
Vol 44 (3) ◽  
pp. 321-330 ◽  
Author(s):  
B Liu ◽  
C L Brubaker ◽  
G Mergeai ◽  
R C Cronn ◽  
J F Wendel
Keyword(s):  
Length Polymorphism ◽  
Fragment Length ◽  
Fragment Length Polymorphism ◽  
Amplified Fragment Length Polymorphism ◽  
Aflp Analysis ◽  
Epigenetic Changes ◽  
Selfed Progeny ◽  
Genomic Changes ◽  
Allopolyploid Speciation ◽  
Polyploid Formation

Recent work has demonstrated that allopolyploid speciation in plants may be associated with non-Mendelian genomic changes in the early generations following polyploid synthesis. To address the question of whether rapid genomic changes also occur in allopolyploid cotton (Gossypium) species, amplified fragment length polymorphism (AFLP) analysis was performed to evaluate nine sets of newly synthesized allotetraploid and allohexaploid plants, their parents, and the selfed progeny from colchicine-doubled synthetics. Using both methylation-sensitive and methylation-insensitive enzymes, the extent of fragment additivity in newly combined genomes was ascertained for a total of approximately 22 000 genomic loci. Fragment additivity was observed in nearly all cases, with the few exceptions most likely reflecting parental heterozygosity or experimental error. In addition, genomic Southern analysis on six sets of synthetic allopolyploids probed with five retrotransposons also revealed complete additivity. Because no alterations were observed using methylation-sensitive isoschizomers, epigenetic changes following polyploid synthesis were also minimal. These indications of genomic additivity and epigenetic stasis during allopolyploid formation provide a contrast to recent evidence from several model plant allopolyploids, most notably wheat and Brassica, where rapid and unexplained genomic changes have been reported. In addition, the data contrast with evidence from repetitive DNAs in Gossypium, some of which are subject to non-Mendelian molecular evolutionary phenomena in extant polyploids. These contrasts indicate polyploid speciation in plants is accompanied by a diverse array of molecular evolutionary phenomena, which will vary among both genomic constituents and taxa.Key words: polyploidy, genome evolution, cotton, Gossypium, amplified fragment length polymorphism (AFLP).

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