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Mutants lacking functional HYD2 homoeologs showed improved seedling growth, but comparable or increased susceptibility to salt stress in tillering plants, suggesting a developmentally restricted role of HYD2 in salt response. Salinity stress threatens global food security by reducing the yield of staple crops such as wheat (Triticum ssp.). Understanding how wheat responds to salinity stress is crucial for developing climate resilient varieties. In this study, we examined the interplay between carotenoid metabolism and the response to salt (NaCl) stress, a specific form of salinity stress, in tetraploid wheat plants with mutations in carotenoid β-hydroxylase 1 (HYD1) and HYD2. Our investigation encompassed both the vulnerable seedling stage and the more developed tillering stage of wheat plant growth. Mutant combinations lacking functional HYD2 homoeologs, including hyd-A2 hyd-B2, hyd-A1 hyd-A2 hyd-B2, hyd-B1 hyd-A2 hyd-B2, and hyd-A1 hyd-B1 hyd-A2 hyd-B2, had longer first true leaves and slightly enhanced root growth during germination under salt stress compared to the segregate wild-type (control) plants. Interestingly, these mutant seedlings also showed decreased levels of neoxanthin and violaxanthin (xanthophylls derived from β-carotene) and an increase in β-carotene in roots. However, tillering hyd mutant and segregate wild-type plants generally did not differ in their height, tiller count, and biomass production under acute or prolonged salt stress, except for decreases in these parameters observed in the hyd-A1 hyd-B1 hyd-A2 hyd-B2 mutant that indicate its heightened susceptibility to salt stress. Taken together, these findings suggest a significant, yet developmentally restricted role of HYD2 homoeologs in salt-stress response in tetraploid wheat. They also show that hyd-A2 hyd-B2 mutant plants, previously demonstrated for possessing enriched nutritional (β-carotene) content, maintain an unimpaired ability to withstand salt stress.

The wheat transcription factor bZIPC1 interacts with FT2 and affects spikelet and grain number per spike. We identified a natural allele with positive effects on these two economically important traits. Loss-of-function mutations and natural variation in the gene FLOWERING LOCUS T2 (FT2) in wheat have previously been shown to affect spikelet number per spike (SNS). However, while other FT-like wheat proteins interact with bZIP-containing transcription factors from the A-group, FT2 does not interact with any of them. In this study, we used a yeast-two-hybrid screen with FT2 as bait and identified a grass-specific bZIP-containing transcription factor from the C-group, designated here as bZIPC1. Within the C-group, we identified four clades including wheat proteins that show Y2H interactions with different sets of FT-like and CEN-like encoded proteins. bZIPC1 and FT2 expression partially overlap in the developing spike, including the inflorescence meristem. Combined loss-of-function mutations in bZIPC-A1 and bZIPC-B1 (bzipc1) in tetraploid wheat resulted in a drastic reduction in SNS with a limited effect on heading date. Analysis of natural variation in the bZIPC-B1 (TraesCS5B02G444100) region revealed three major haplotypes (H1-H3), with the H1 haplotype showing significantly higher SNS, grain number per spike and grain weight per spike than both the H2 and H3 haplotypes. The favorable effect of the H1 haplotype was also supported by its increased frequency from the ancestral cultivated tetraploids to the modern tetraploid and hexaploid wheat varieties. We developed markers for the two non-synonymous SNPs that differentiate the bZIPC-B1b allele in the H1 haplotype from the ancestral bZIPC-B1a allele present in all other haplotypes. These diagnostic markers are useful tools to accelerate the deployment of the favorable bZIPC-B1b allele in pasta and bread wheat breeding programs.

Large-scale production of triploid oysters requires tetraploids as broodstock; hence, tetraploidy is a key asset for the triploid oyster industry. To explore the possibility of obtaining new allotetraploid strains with improved traits through hybridization and polyploidization, we conducted a comparative study for growth, survival, and gonadal development of tetraploid Crassostrea gigas, tetraploid C. angulata, and four allotetraploids. Firstly, allotriploid GGA (C. gigas ♀ × C. angulata ♂) and AAG (C. angulata ♀ × C. gigas ♂) were obtained from the hybridization between diploid C. gigas and diploid C. angulata by inhibiting the polar body II. Subsequently, allotetraploid GGGA (triploid C. gigas ♀ × diploid C. angulata ♂), allotetraploid AAAG (triploid C. angulata ♀ × diploid C. gigas ♂), allotetraploid GGAG (allotriploid GGA ♀ × diploid C. gigas ♂), allotetraploid AAGG (allotriploid AAG ♀ × diploid C. gigas ♂), autotetraploid GGGG (triploid C. gigas ♀ × diploid C. gigas ♂), and autotetraploid AAAA (triploid C. angulata ♀ × diploid C. angulata ♂) were obtained by inhibiting polar body I. The growth, survival, and gonad development of six groups (GGGA, AAAG, GGAG, AAGG, GGGG, and AAAA) were assessed. There were no detectable differences in fertilization and hatching rates among the six groups. Flow cytometry analysis showed that the tetraploid ratios of the four allotetraploid groups exceeded 88% on day 20. At larval stage, the allotetraploids GGGA and GGAG groups had higher growth rates and cumulative survival rates than the autotetraploid groups. Field-based phenotyping at three sites indicated that certain allotetraploid groups exhibited higher growth and survival compared to the autotetraploid groups. In particular, the best group over 9 months of testing was the allotetraploid GGAG, which significantly outperformed the autotetraploid groups in growth and survival. Furthermore, most of the individuals from the four allotetraploids were fully mature, with morphologically normal oocytes or sperm. The establishment of these four allotetraploids offers new germplasm resources for oyster genetic improvement and commercial production. [ABSTRACT FROM AUTHOR]

Background: Triploid bananas are almost sterile. However, we succeeded in harvesting seeds from two edible triploid banana individuals (Genotype: ABB) in our conservation repository where various wild diploid bananas were also grown. The resulting rare offspring survived to seedling stages. DNA content analyses reveal that they are tetraploid. Since bananas contain maternally inherited plastids and paternally inherited mitochondria, we sequenced and assembled plastomes and mitogenomes of these seedlings to trace their hybridization history. Results: The coding sequences of both organellar genomic scaffolds were extracted, aligned, and concatenated for constructing phylogenetic trees. Our results suggest that these tetraploid seedlings be derived from hybridization between edible triploid bananas and wild diploid Musa balbisiana (BB) individuals. We propose that generating female triploid gametes via apomeiosis may allow the triploid maternal bananas to produce viable seeds. Conclusions: Our study suggests a practical avenue towards expanding genetic recombination and increasing genetic diversity of banana breeding programs. Further cellular studies are needed to understand the fusion and developmental processes that lead to formation of hybrid embryos in banana reproduction, polyploidization, and evolution. [ABSTRACT FROM AUTHOR]

BackgroundThe genetic information contained in the genome of an organism is organized in genes and regulatory elements that control gene expression. The genomes of multiple plants species have already been sequenced and the gene repertory have been annotated, however, cis-regulatory elements remain less characterized, limiting our understanding of genome functionality. These elements act as open platforms for recruiting both positive- and negative-acting transcription factors, and as such, chromatin accessibility is an important signature for their identification.ResultsIn this work we developed a transgenic INTACT [isolation of nuclei tagged in specific cell types] system in tetraploid wheat for nuclei purifications. Then, we combined the INTACT system together with the assay for transposase-accessible chromatin with sequencing [ATAC-seq] to identify open chromatin regions in wheat root tip samples. Our ATAC-seq results showed a large enrichment of open chromatin regions in intergenic and promoter regions, which is expected for regulatory elements and that is similar to ATAC-seq results obtained in other plant species. In addition, root ATAC-seq peaks showed a significant overlap with a previously published ATAC-seq data from wheat leaf protoplast, indicating a high reproducibility between the two experiments and a large overlap between open chromatin regions in root and leaf tissues. Importantly, we observed overlap between ATAC-seq peaks and cis-regulatory elements that have been functionally validated in wheat, and a good correlation between normalized accessibility and gene expression levels.ConclusionsWe have developed and validated an INTACT system in tetraploid wheat that allows rapid and high-quality nuclei purification from root tips. Those nuclei were successfully used to performed ATAC-seq experiments that revealed open chromatin regions in the wheat genome that will be useful to identify cis-regulatory elements. The INTACT system presented here will facilitate the development of ATAC-seq datasets in other tissues, growth stages, and under different growing conditions to generate a more complete landscape of the accessible DNA regions in the wheat genome.

Key messageFunctional redundancy and subfunctionalization of β-hydroxylases in tetraploid wheat tissues open up opportunities for manipulation of carotenoid metabolism for trait improvement. The genetic diversity provided by subgenome homoeologs in allopolyploid wheat can be leveraged for developing improved wheat varieties with modified chemical traits, including profiles of carotenoids, which play critical roles in photosynthesis, photoprotection, and growth regulation. Carotenoid profiles are greatly influenced by hydroxylation catalyzed by β-hydroxylases (HYDs). To genetically dissect the contribution of HYDs to carotenoid metabolism and wheat growth and yield, we isolated loss-of-function mutants of the two homoeologs of HYD1 (HYD-A1 and HYD-B1) and HYD2 (HYD-A2 and HYD-B2) from the sequenced ethyl methanesulfonate mutant population of the tetraploid wheat cultivar Kronos, and generated various mutant combinations. Although functional redundancy between HYD1 and HYD2 paralogs was observed in leaves, HYD1 homoeologs contributed more than HYD2 homoeologs to carotenoid β-ring hydroxylation in this tissue. By contrast, the HYD2 homoeologs functioned toward production of lutein, the major carotenoid in mature grains, whereas HYD1 homoeologs had a limited role. These results collectively suggested subfunctionalization of HYD genes and homoeologs in different tissues of tetraploid wheat. Despite reduced photoprotective responses observed in the triple hyd-A1 hyd-B1 hyd-A2 and the quadruple hyd-A1 hyd-B1 hyd-A2 hyd-B2 combinatorial mutants, comprehensive plant phenotyping analysis revealed that all mutants analyzed were comparable to the control for growth, yield, and fertility, except for a slight delay in anthesis and senescence as well as accelerated germination in the quadruple mutant. Overall, this research takes steps toward untangling the functions of HYDs in wheat and has implications for improving performance and consumer traits of this economically important global crop.

Cytogenetics can be used as a tool to study the evolution of polyploidy and taxonomy. Here we focus on aquatic African pipids, dwarf clawed frogs (Hymenochirus). Our study reveals that dwarf clawed frogs, present for decades in captivity, are best referred to as Hymenochirus sp. instead of the commonly used name ' H. boettgeri ' or sometimes ' H. curtipes '. We present the first karyotype from a morphologically identified specimen of H. boettgeri with a known locality in the north-western Congo, which is tetraploid with 2n = 36. The captive Hymenochirus species has been found diploid in previous studies with different reported chromosome numbers; here we reveal 2n = 20A + 1B chromosomes. Our findings suggest that the tetraploid H. boettgeri karyotype evolved through fusion of two biarmed chromosomes and subsequent allotetraploidization, and is functionally diploid, similar to the origin of tetraploid clawed frogs in the subgenus Xenopus. We observed the stable presence of a single B chromosome in both sexes of our individuals from the captive population of Hymenochirus sp. However, additional investigation is necessary to clarify whether there is variation in the number of A and B chromosomes among populations, individuals, and/or tissues. Further research is also needed to understand the evolution and taxonomy of the genus Hymenochirus. [ABSTRACT FROM AUTHOR]

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The new species, Thliphthisa sapphus sp. nov. (Rubiaceae, Rubieae), a narrow endemic of the white cliffs of Lefkátas on the southwest coast of Lefkada (Greece) is described and illustrated and an IUCN assessment is presented. Vegetation relevés were performed at the single known locality, limestone cliffs facing the sea and revealed a new association, the Thliphthisa sapphus-Lomelosietum dallaportae. The chromosome number of Thliphthisa sapphus was determined as 2n = 4x = 44, being the single tetraploid species in the genus to date. The species also differs markedly morphologically from its morphologically closest relatives, two Greek steno-endemic oreophytes, Th. baenitzii and Th. muscosa by the following characters: densely setose mericarps and corolla, tetraploidy and by its distribution. An identification key for the Greek species of Thliphthisa is provided. Th. sapphus constitutes the westernmost outpost of a group of Greek steno-endemics, highlighting the importance of coastal habitats and their protection as refugia for poorly competitive chamaephytes. [ABSTRACT FROM AUTHOR]

Genetic manipulation (either restraint or enhancement) of the biosynthesis pathway of α-linolenic acid (ALA) in seed oil is an important goal in Brassica napus breeding. B. napus is a tetraploid plant whose genome often harbors four and six homologous copies, respectively, of the two fatty acid desaturases FAD2 and FAD3, which control the last two steps of ALA biosynthesis during seed oil accumulation. In this study, we compared their promoters, coding sequences, and expression levels in three high-ALA inbred lines 2006L, R8Q10, and YH25005, a low-ALA line A28, a low-ALA/high-oleic-acid accession SW, and the wildtype ZS11. The expression levels of most FAD2 and FAD3 homologs in the three high-ALA accessions were higher than those in ZS11 and much higher than those in A28 and SW. The three high-ALA accessions shared similar sequences with the promoters and CDSs of BnFAD3.C4 and BnFAD3.A3. In A28 and SW, substitution of three amino acid residues in BnFAD2.A5 and BnFAD2.C5, an absence of BnFAD2.C1 locus, and a 549 bp long deletion on the BnFAD3.A3 promoter were detected. The profile of BnFAD2 mutation in the two low-ALA accessions A28 and SW is different from that reported in previous studies. The mutations in BnFAD3 in the high-ALA accessions are reported for the first time. In identifying the sites of these mutations, we provide detailed information to aid the design of molecular markers for accelerated breeding schemes. [ABSTRACT FROM AUTHOR]

Ethiopian mustard (Brassica carinata) is an ancient crop with remarkable stress resilience and a desirable seed fatty acid profile for biofuel uses. Brassica carinata is one of six Brassica species that share three major genomes from three diploid species (AA, BB, and CC) that spontaneously hybridized in a pairwise manner to form three allotetraploid species (AABB, AACC, and BBCC). Of the genomes of these species, that of B. carinata is the least understood. Here, we report a chromosome scale 1.31-Gbp genome assembly with 156.9-fold sequencing coverage for B. carinata, completing the reference genomes comprising the classic Triangle of U, a classical theory of the evolutionary relationships among these six species. Our assembly provides insights into the hybridization event that led to the current B. carinata genome and the genomic features that gave rise to the superior agronomic traits of B. carinata. Notably, we identified an expansion of transcription factor networks and agronomically important gene families. Completion of the Triangle of U comparative genomics platform has allowed us to examine the dynamics of polyploid evolution and the role of subgenome dominance in the domestication and continuing agronomic improvement of B. carinata and other Brassica species.

Background: SRO (Similar to RCD1) genes family is largely recognized for their importance in the growth, development, and in responding to environmental stresses. However, genome-wide identification and functional characterization of SRO genes from cotton species have not been reported so far. Results: A total of 36 SRO genes were identified from four cotton species. Phylogenetic analysis divided these genes into three groups with distinct structure. Syntenic and chromosomal distribution analysis indicated uneven distribution of GaSRO, GrSRO, GhSRO, and GbSRO genes on A2, D5 genomes, Gh-At, Gh-Dt, Gb-At, and Gb-Dt subgenomes, respectively. Gene duplication analysis revealed the presence of six duplicated gene pairs among GhSRO genes. In promoter analysis, several elements responsive to the growth, development and hormones were found in GhSRO genes, implying gene induction during cotton growth and development. Several miRNAs responsive to plant growth and abiotic stress were predicted to target 12 GhSRO genes. Organ-specific expression profiling demonstrated the roles of GhSRO genes in one or more tissues. In addition, specific expression pattern of some GhSRO genes during ovule development depicted their involvement in these developmental processes. Conclusion: The data presented in this report laid a foundation for understanding the classification and functions of SRO genes in cotton. [ABSTRACT FROM AUTHOR]

Actinidia arguta, known as hardy kiwifruit, is a widely cultivated species with distinct botanical characteristics such as small and smooth-fruited, rich in beneficial nutrients, rapid softening and tolerant to extremely low temperatures. It contains the most diverse ploidy types, including diploid, tetraploid, hexaploid, octoploid, and decaploid. Here we report a haplotype-resolved tetraploid genome (A. arguta cv. 'Longcheng No.2') containing four haplotypes, each with 40,859, 41,377, 39,833 and 39,222 protein-coding genes. We described the phased genome structure, synteny, and evolutionary analyses to identify and date possible WGD events. Ks calculations for both allelic and paralogous genes pairs throughout the assembled haplotypic individuals showed its tetraploidization is estimated to have formed ~ 1.03 Mya following Ad-α event occurred ~ 18.7 Mya. Detailed annotations of NBS-LRRs or CBFs highlight the importance of genetic variations coming about after polyploidization in underpinning ability of immune responses or environmental adaptability. WGCNA analysis of postharvest quality indicators in combination with transcriptome revealed several transcription factors were involved in regulating ripening kiwi berry texture. Taking together, the assembly of an A. arguta tetraploid genome provides valuable resources in deciphering complex genome structure and facilitating functional genomics studies and genetic improvement for kiwifruit and other crops. [ABSTRACT FROM AUTHOR]

Stem rust, caused by Puccinia graminis f. sp. tritici (Pgt), threatens global wheat production. Development of cultivars with increased resistance to stem rust by identification, mapping, and deployment of resistance genes is the best strategy for controlling the disease. In this study, we performed fine mapping and characterization of the all-stage stem rust resistance (Sr) gene Sr8155B1 from the durum wheat line 8155-B1. In seedling tests of biparental populations, Sr8155B1 was effective against six Chinese Pgt races tested. In a segregating population of 5060 gametes, Sr8155B1 was mapped to a 0.06-cM region flanked by markers Pku2772 and Pku43365, corresponding to 1.5- and 2.7-Mb regions in the Svevo and Chinese Spring reference genomes. Both regions include several typical nucleotide-binding leucine-rich repeat (NLR) and protein kinase genes that represent candidate genes. Among them, three NLR genes and three receptor-like protein kinases were highly polymorphic between the parental lines and their transcripts were upregulated in the homozygous resistant line TdR2 relative to its susceptible sister line TdS4. Four markers (Pku2772, Pku43365, Pku2950, and Pku3721) developed in this study, together with seedling resistance responses, correctly predicted Sr8155B1 absence or presence in 78 tetraploid wheat genotypes tested. The presence of Sr8155B1 in tetraploid wheat accessions CItr 14916, PI 197492, and PI 197493 was confirmed by mapping in three F2 populations. The genetic map and linked markers developed in this study may accelerate the deployment of Sr8155B1-mediated resistance in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Antioxidant defense status was examined during early developmental stages of rainbow trout, Oncorhynchus mykiss, as affected by heat shock (HS) treatment to induce tetraploidy. Samples were collected at 3850 degree-min post-fertilization at 10 °C and at eyed, hatch, swim-up, in addition to fry stages to determine the activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and levels of vitamin C, A and E as well as malondialdehyde (MDA). HS treatment caused a significant reduction in survival, but not affected growth compared to the control. CAT and SOD activities peaked at hatch, whereas GPx activity reached a maximum at the swim-up stage, showing similar patterns, however, significantly higher activities in the HS group. Vitamin levels were at their minimum at the hatch in both groups, while significantly lower in the HS groups. Vitamin levels were at their highest at the fry stage, with the exception of low vitamin E in the HS group. The levels of MDA showed a steady increase during development, with consistently higher levels in the HS group. These results suggest that HS treatment and/or tetraploidy status cause high oxidative stress, as evidenced by higher activity of antioxidant enzymes and MDA levels, and lower levels of vitamins. [ABSTRACT FROM AUTHOR]

Experiments were conducted to optimize triploid induction parameters, and assess triploid sterility, in burbot. Duration and timing of shocks were based on degree minutes, temperature multiplied by time, denoted as °C min. Hydrostatic shock experiments investigated the duration of shock using 7500 or 8500 psi at 180°C min post‐fertilization. Thermal shocks investigated duration of shock and post‐fertilization shock timing using a shock of 16°C. Sterility experiments investigated egg survival when diploids were crossed with triploids. Hydrostatic shock of 7500 psi for 10 or 20°C min can induce triploidy ≥90% and exhibits survival that is statistically similar, p ≤ 0.05, to controls. Hydrostatic shock of 8500 psi for 5 or 10°C min yielded triploid induction of 93% and 100%, respectively, with survival that is statistically similar to controls, p ≤ 0.05. Thermal induction experiments indicated shocks at 120°C min post‐fertilization, for durations between 350 and 450°C min, have potential to induce triploidy ≥90% while facilitating survival statistically similar to controls, p ≤ 0.05. Induction of tetraploidy was observed. Sterility experiments determined that triploid burbot are functionally sterile. These results may allow production of burbot where sterility is required. [ABSTRACT FROM AUTHOR]

Polyploidy results from whole-genome duplication and is a unique form of heritable variation with pronounced evolutionary implications. Different ploidy levels, or cytotypes, can exist within a single species, and such systems provide an opportunity to assess how ploidy variation alters phenotypic novelty, adaptability, and fitness, which can, in turn, drive the development of unique ecological niches that promote the coexistence of multiple cytotypes. Switchgrass, Panicum virgatum, is a widespread, perennial C4 grass in North America with multiple naturally occurring cytotypes, primarily tetraploids (4×) and octoploids (8×). Using a combination of genomic, quantitative genetic, landscape, and niche modeling approaches, we detect divergent levels of genetic admixture, evidence of niche differentiation, and differential environmental sensitivity between switchgrass cytotypes. Taken together, these findings support a generalist (8×)–specialist (4×) trade-off. Our results indicate that the 8× represent a unique combination of genetic variation that has allowed the expansion of switchgrass’ ecological niche and thus putatively represents a valuable breeding resource.

CRISPR/Cas9-mediated genome editing has become an extremely powerful technique used to modify gene expression in many organisms, including parasitic protists. Giardia intestinalis, a protist parasite that infects approximately 280 million people around the world each year, has been eluding the use of CRISPR/Cas9 to generate knockout cell lines due to its tetraploid genome. In this work, we show the ability of the in vitro assembled CRISPR/Cas9 components to successfully edit the genome of G. intestinalis. The cell line that stably expresses Cas9 in both nuclei of G. intestinalis showed effective recombination of the cassette containing the transcription units for the gRNA and the resistance marker. This highly efficient process led to the removal of all gene copies at once for three independent experimental genes, mem, cwp1 and mlf1. The method was also applicable to incomplete disruption of the essential gene, as evidenced by significantly reduced expression of tom40. Finally, testing the efficiency of Cas9-induced recombination revealed that homologous arms as short as 150 bp can be sufficient to establish a complete knockout cell line in G. intestinalis.

Grains of tetraploid wheat (Triticum turgidum L.) mainly accumulate the non-provitamin A carotenoid lutein-with low natural variation in provitamin A β-carotene in wheat accessions necessitating alternative strategies for provitamin A biofortification. Lycopene ɛ-cyclase (LCYe) and β-carotene hydroxylase (HYD) function in diverting carbons from β-carotene to lutein biosynthesis and catalyzing the turnover of β-carotene to xanthophylls, respectively. However, the contribution of LCYe and HYD gene homoeologs to carotenoid metabolism and how they can be manipulated to increase β-carotene in tetraploid wheat endosperm (flour) is currently unclear. We isolated loss-of-function Targeting Induced Local Lesions in Genomes (TILLING) mutants of LCYe and HYD2 homoeologs and generated higher order mutant combinations of lcye-A, lcye-B, hyd-A2, and hyd-B2. Hyd-A2 hyd-B2, lcye-A hyd-A2 hyd-B2, lcye-B hyd-A2 hyd-B2, and lcye-A lcye-B hyd-A2 hyd-B2 achieved significantly increased β-carotene in endosperm, with lcye-A hyd-A2 hyd-B2 exhibiting comparable photosynthetic performance and light response to control plants. Comparative analysis of carotenoid profiles suggests that eliminating HYD2 homoeologs is sufficient to prevent β-carotene conversion to xanthophylls in the endosperm without compromising xanthophyll production in leaves, and that β-carotene and its derived xanthophylls are likely subject to differential catalysis mechanisms in vegetative tissues and grains. Carotenoid and gene expression analyses also suggest that the very low LCYe-B expression in endosperm is adequate for lutein production in the absence of LCYe-A. These results demonstrate the success of provitamin A biofortification using TILLING mutants while also providing a roadmap for guiding a gene editing-based approach in hexaploid wheat.

ABSTRACTMicrosporidia are obligate intracellular eukaryotic parasites with an extremely broad host range. They have both economic and public health importance. Ploidy in microsporidia is variable, with a few species formally identified as diploid and one as polyploid. Given the increase in the number of studies sequencing microsporidian genomes, it is now possible to assess ploidy levels across all currently explored microsporidian diversity. We estimate ploidy for all microsporidian data sets available on the Sequence Read Archive using k-mer-based analyses, indicating that polyploidy is widespread in Microsporidia and that ploidy change is dynamic in the group. Using genome-wide heterozygosity estimates, we also show that polyploid microsporidian genomes are relatively homozygous, and we discuss the implications of these findings on the timing of polyploidization events and their origin.IMPORTANCEMicrosporidia are single-celled intracellular parasites, distantly related to fungi, that can infect a broad range of hosts, from humans all the way to protozoans. Exploiting the wealth of microsporidian genomic data available, we use k-mer-based analyses to assess ploidy status across the group. Understanding a genome’s ploidy is crucial in order to assemble it effectively and may also be relevant for better understanding a parasite’s behavior and life cycle. We show that tetraploidy is present in at least six species in Microsporidia and that these polyploidization events are likely to have occurred independently. We discuss why these findings may be paradoxical, given that Microsporidia, like other intracellular parasites, have extremely small, reduced genomes.

Summary: In this study, we report on mosaic variegated aneuploidy (MVA) syndrome with tetraploidy and predisposition to infertility in a family. Sequencing analysis identified that the CEP192 biallelic variants (c.1912C>T, p.His638Tyr and c.5750A>G, p.Asn1917Ser) segregated with microcephaly, short stature, limb-extremity dysplasia, and reduced testicular size, while CEP192 monoallelic variants segregated with infertility and/or reduced testicular size in the family. In 1,264 unrelated patients, variant screening for CEP192 identified a same variant (c.5750A>G, p.Asn1917Ser) and other variants significantly associated with infertility. Two lines of Cep192 mice model that are equivalent to human variants were generated. Embryos with Cep192 biallelic variants arrested at E7 because of cell apoptosis mediated by MVA/tetraploidy cell acumination. Mice with heterozygous variants replicated the predisposition to male infertility. Mouse primary embryonic fibroblasts with Cep192 biallelic variants cultured in vitro showed abnormal morphology, mitotic arresting, and disruption of spindle formation. In patient epithelial cells with biallelic variants cultured in vitro, the number of cells arrested during the prophase increased because of the failure of spindle formation. Accordingly, we present mutant CEP192, which is a link for the MVA syndrome with tetraploidy and the predisposition to male infertility.

Introduction: Chromosome mosaicism and low-grade mosaicism present a challenge for diagnosis in the era of SNP array and NGS. Tetraploidy is a rare numerical chromosomal abnormality characterized by the presence of four copies of each chromosome. The prevalence of tetraploidy/diploidy mosaicism cases is extremely rare in the human population. Accurate estimates of the frequency of this chromosomal anomaly are lacking due to its classification as an extremely rare and difficult-to-detect condition. Methods: In this report, we describe two cases involving challenging diagnoses of tetraploidy/diploidy and trisomy 12. We utilized advanced genetic testing techniques, including SNP array, to examine the chromosomal abnormalities in these cases. We compared the results from SNP array to conventional G band karyotyping to assess the utility of first-tier prenatal testing methods. Results:Our analysis revealed two cases of tetraploidy/diploidy and trisomy 12 with atypical presentations. SNP array analysis provided higher resolution and more precise information about the chromosomal anomalies in these cases compared to conventional G band karyotyping. Additionally, the prevalence of tetraploidy/diploidy mosaicism was confirmed to be extremely rare in the population. Discussion: Low-level mosaicism is difficult to diagnose, and in many cases, it has traditionally been identified through techniques such as G band karyotype or FISH. Microarray has become an invaluable diagnostic tool for detecting chromosomal abnormalities, offering high-resolution insights. However, it may not always be able to detect rare occurrences of tetraploidy or tetraploidy/diploidy mosaicism. As a result, it is recommended to perform a G band karyotype analysis after obtaining a negative microarray result before considering other diagnostic methods with a potentially higher yield of diagnosis. For the detection of lowlevel mosaicism, combined diagnostic methods should be considered. The diagnosis of mosaicism is a multistep process that can be time-consuming, often requiring the application of more than one diagnostic technique. This approach is crucial for accurate diagnosis and comprehensive patient care.Further research is warranted to better understand the underlying mechanisms of these rare chromosomal anomalies and to develop more effective diagnostic strategies for challenging cases. [ABSTRACT FROM AUTHOR]

Polyploid cells contain more than two copies of each chromosome. Polyploidy has important roles in development, evolution, and tissue regeneration/repair, and can arise as a programmed polyploidization event or be triggered by stress. Cancer cells are often polyploid. C. elegans nematodes are typically diploid, but stressors such as heat shock and starvation can trigger the production of tetraploid offspring. In this study, we utilized a recently published protocol to generate stable tetraploid strains of C. elegans and compared their physiological traits and sensitivity to two DNA-damaging chemotherapeutic drugs, cisplatin and doxorubicin. As prior studies have shown, tetraploid worms are approximately 30% longer, shorter-lived, and have a smaller brood size than diploids. We investigated the reproductive defect further, determining that tetraploid worms have a shorter overall germline length, a higher rate of germ cell apoptosis, more aneuploidy in oocytes and offspring, and larger oocytes and embryos. We also found that tetraploid worms are modestly protected from growth delay from the chemotherapeutics but are similarly or more sensitive to reproductive toxicity. Transcriptomic analysis revealed differentially expressed pathways that may contribute to sensitivity to stress. This study reveals phenotypic consequences of whole-animal tetraploidy that make C. elegans an excellent model for ploidy differences. [ABSTRACT FROM AUTHOR]

Tetraploidy is a hallmark of broad cancer types, but it remains largely unknown which aspects of cellular processes are influenced by tetraploidization in human cells. Here, we found that tetraploid HCT116 cells manifested severe cell shape instability during cytokinesis, unlike their diploid counterparts. The cell shape instability accompanied the formation of protrusive deformation at the cell poles, indicating ectopic contractile activity of the cell cortex. While cytokinesis regulators such as RhoA and anillin correctly accumulated at the equatorial cortex, myosin II was over-accumulated at the cell poles, specifically in tetraploid cells. Suppression of myosin II activity by Y27632 treatment restored smooth cell shape in tetraploids during cytokinesis, indicating dysregulation of myosin II as a primary cause of the cell shape instability in the tetraploid state. Our results demonstrate a new aspect of the dynamic cellular process profoundly affected by tetraploidization in human cells, which provides a clue to molecular mechanisms of tetraploidy-driven pathogenic processes. • HCT116 cells show drastic cell shape instability during cytokinesis, specifically in the tetraploid state. • Myosin II over-accumulates at the polar cortex in a tetraploidy-specific manner. • Pharmacological suppression of myosin II restores cell shape instability in tetraploid cytokinesis cells. [ABSTRACT FROM AUTHOR]

Polyploidy and metastasis are associated with a low probability of disease-free survival in cancer patients. Polyploid cells are known to facilitate tumorigenesis. However, few data associate polyploidization with metastasis. Here, by generating and using diploid (2n) and tetraploid (4n) clones from malignant fibrous histiocytoma (MFH) and colon carcinoma (RKO), we demonstrate the migration and invasion advantage of tetraploid cells in vitro using several assays, including the wound healing, the OrisTM two-dimensional cell migration, single-cell migration tracking by video microscopy, the Boyden chamber, and the xCELLigence RTCA real-time cell migration. Motility advantage was observed despite tetraploid cell proliferation weakness. We could also demonstrate preferential metastatic potential in vivo for the tetraploid clone using the tail vein injection in mice and tracking metastatic tumors in the lung. Using the Mitelman Database of Chromosome Aberrations in Cancer, we found an accumulation of polyploid karyotypes in metastatic tumors compared to primary ones. This work reveals the clinical relevance of the polyploid subpopulation and the strategic need to highlight polyploidy in preclinical studies as a therapeutic target for metastasis. [ABSTRACT FROM AUTHOR]

Miscarriage is an important problem in human reproduction, affecting 10–15 % of clinically recognized pregnancies. The cases of embryonic death can be divided into missed abortion (MA), for which the ultrasound sign of the embryo death is the absence of cardiac activity, and anembryonic pregnancy (AP) without an embryo in the gestational sac. The aim of this study was to compare the frequency of chromosomal abnormalities in extraembryonic tissues detected by conventional cytogenetic analysis of spontaneous abortions depending on the presence or absence of an embryo. This is a retrospective study of 1551 spontaneous abortions analyzed using GTG-banding from 1990 to 2022 (266 cases of AP and 1285 cases of MA). A comparative analysis of the frequency of chromosomal abnormalities and the distribution of karyotype frequencies depending on the presence of an embryo in the gestational sac was carried out. Statistical analysis was performed using a chi-square test with a p < 0.05 significance level. The total frequency of chromosomal abnormalities in the study was 53.6 % (832/1551). The proportion of abnormal karyotypes in the AP and MA groups did not differ significantly and amounted to 57.1 % (152/266) and 52.9 % (680/1285) for AP and MA, respectively (p = 0.209). Sex chromosome aneuploidies and triploidies were significantly less common in the AP group than in the MA group (2.3 % (6/266) vs 6.8 % (88/1285), p = 0.005 and 4.9 % (13/266) vs 8.9 % (114/1285), p = 0.031, respectively). Tetraploidies were registered more frequently in AP compared to MA (12.4 % (33/266) vs. 8.2 % (106/1285), p = 0.031). The sex ratio among abortions with a normal karyotype was 0.54 and 0.74 for AP and MA, respectively. Thus, although the frequencies of some types of chromosomal pathology differ between AP and MA, the total frequency of chromosomal abnormalities in AP is not increased compared to MA, which indicates the need to search for the causes of AP at other levels of the genome organization, including microstructural chromosomal rearrangements, monogenic mutations, imprinting disorders, and epigenetic abnormalities.

Introduction: Chromosome mosaicism and low-grade mosaicism present a challenge for diagnosis in the era of SNP array and NGS. Tetraploidy is a rare numerical chromosomal abnormality characterized by the presence of four copies of each chromosome. The prevalence of tetraploidy/diploidy mosaicism cases is extremely rare in the human population. Accurate estimates of the frequency of this chromosomal anomaly are lacking due to its classification as an extremely rare and difficult-to-detect condition.Methods: In this report, we describe two cases involving challenging diagnoses of tetraploidy/diploidy and trisomy 12. We utilized advanced genetic testing techniques, including SNP array, to examine the chromosomal abnormalities in these cases. We compared the results from SNP array to conventional G band karyotyping to assess the utility of first-tier prenatal testing methods.Results:Our analysis revealed two cases of tetraploidy/diploidy and trisomy 12 with atypical presentations. SNP array analysis provided higher resolution and more precise information about the chromosomal anomalies in these cases compared to conventional G band karyotyping. Additionally, the prevalence of tetraploidy/diploidy mosaicism was confirmed to be extremely rare in the population.Discussion: Low-level mosaicism is difficult to diagnose, and in many cases, it has traditionally been identified through techniques such as G band karyotype or FISH. Microarray has become an invaluable diagnostic tool for detecting chromosomal abnormalities, offering high-resolution insights. However, it may not always be able to detect rare occurrences of tetraploidy or tetraploidy/diploidy mosaicism. As a result, it is recommended to perform a G band karyotype analysis after obtaining a negative microarray result before considering other diagnostic methods with a potentially higher yield of diagnosis. For the detection of low-level mosaicism, combined diagnostic methods should be considered. The diagnosis of mosaicism is a multistep process that can be time-consuming, often requiring the application of more than one diagnostic technique. This approach is crucial for accurate diagnosis and comprehensive patient care. Further research is warranted to better understand the underlying mechanisms of these rare chromosomal anomalies and to develop more effective diagnostic strategies for challenging cases.

Citrus are classified as salt-sensitive crops. However, a large diversity has been observed regarding the trends of tolerance among citrus. In the present article, physiological and biochemical studies of salt stress tolerance were carried out according to the level of polyploidy of different citrus genotypes. We particularly investigated the impact of tetraploidy in trifoliate orange (Poncirus trifoliata (L.) Raf.) (PO4x) and Cleopatra mandarin (Citrus reshni Hort. Ex Tan.) (CL4x) on the tolerance to salt stress compared to their respective diploids (PO2x and CL2x). Physiological parameters such as gas exchange, ions contents in leaves and roots were analyzed. Roots and leaves samples were collected to measure polyphenol, malondialdehyde (MDA), ascorbate and H2O2 contents but also to measure the activities of enzymes involved in the detoxification of active oxygen species (ROS). Under control conditions, the interaction between genotype and ploidy allowed to discriminate different behavior in terms of photosynthetic and antioxidant capacities. These results were significantly altered when salt stress was applied when salt stress was applied. Contrary to the most sensitive genotype, that is to say the diploid trifoliate orange PO2x, PO4x was able to maintain photosynthetic activity under salt stress and had better antioxidant capacities. The same observation was made regarding the CL4x genotype known to be more tolerant to salt stress. Our results showed that tetraploidy may be a factor that could enhance salt stress tolerance in citrus. [ABSTRACT FROM AUTHOR]

Polyploidy, a common phenomenon in the evolution of plant species, plays an imperative role in plant diversification. Bride rose poppy (Papaver fugax Poir.) is a valuable medicinal plant due to its various alkaloids, such as fugapavin, mecambrin, romerine, salutaridine, protopine, and thebaine. In this study, we used quantitative polymerase chain reaction (qRT-PCR) to study the differential expression of four key genes, including CYPB80B1 ((S)-N-methylcoclaurine-3'-hydroxylase), MLP (major latex protein), 6OMT ((S)- norcoclaurine-6-O-methyltransferase), and salAT (7(S)-salutaridinol-7-O-acetyltransferase), involved in the biosynthesis of poppy alkaloids. The assessment of extracted RNA samples on 1% agarose gel electrophoresis and NanoDrop showed the proper quality and quantity of isolated RNA samples for cDNA synthesis. Gene expression analysis through qRT-PCR revealed increased expression of CYP80B1, MLP, and SalAT genes and decreased expression of 6OMT in tetraploid plants compared with diploids. Our results indicated that autotetraploidy induction could be applied, as a useful method, to increase morphine production in P. fugax. [ABSTRACT FROM AUTHOR]

Polyploidy, frequently observed in citrus species, aids in achieving better adaptation to environmental stresses. In this context, the current work aims to develop stable tetraploids in citrus rootstock cultivars, viz., Rough lemon, Rangpur lime and Alemow, through in vitro colchicine treatments. Seed-derived explants were obtained by culturing sterile seeds on MS basal media. Seedlings with a size of 5–8 mm (hypocotyl) were exposed to colchicine treatment. After treatment, the surviving seedlings were minigrafted onto six-month-old rootstock for better growth. Colchicine concentrations of 0.1%, 0.2%, 0.3% and control for durations of 16 or 24 h were tested with respect to the induction of polyploidisation. Treatment with 0.1% colchicine for 24 h resulted in high rates of mutation for polyploidisation and showed the highest tetraploid induction percentage (18.3%) in all the rootstock cultivars. High colchicine concentration and long exposure time decreased the survival of the observed seedlings. Flow cytometry and cytological methods were used for confirmation of autotetraploidy in the analysed samples. The surviving seedlings were identified on the basis of morphological and cytological variables, such as leaf area and stomata size, which significantly increased with increasing ploidy level. The proposed method was found to be an effective way to induce the polyploidy in Rangpur lime, Rough lemon and Alemow rootstocks. [ABSTRACT FROM AUTHOR]

Chromosomal abnormalities are an important cause of especially early miscarriages. The aim of this study was to analyze the chromosomal aberrations and determine the frequencies of numerical and structural chromosome abnormalities in spontaneous abortion materials. This was a prospective research and ninety two abortion samples obtained from women who had one or more miscarriages were included in the study. Conventional karyotype analysis was performed on each sample to identify possible chromosomal abnormalities. By karyotype analysis, 11 polyploidy cases, (9 triploids and 2 tetraploids), 8 trisomies (one of which was mosaic), 2 monosomies (monosomy X), 1 isochromosome, 1 Xq deletion, and 4 translocations were detected in abortion materials. Isochromosome and Xq deletion cases were also mosaic. In addition, five polymorphic variants were revealed. We found higher paternal age in polyploidy cases. The most common anomaly we found in abortion materials was polyploidy. This was followed by aneuploidy (trisomy and monosomy). Polyploidy (triploidy or tetraploidy) emerged as an important cause in cases of spontaneous abortion. Paternal age may be associated with polyploidy especially triploidy. [ABSTRACT FROM AUTHOR]

Whole genome duplication (WGD) or polyploidization can occur at the cellular, tissue, and organismal levels. At the cellular level, tetraploidization has been proposed as a driver of aneuploidy and genome instability and correlates strongly with cancer progression, metastasis, and the development of drug resistance. WGD is also a key developmental strategy for regulating cell size, metabolism, and cellular function. In specific tissues, WGD is involved in normal development (e.g., organogenesis), tissue homeostasis, wound healing, and regeneration. At the organismal level, WGD propels evolutionary processes such as adaptation, speciation, and crop domestication. An essential strategy to further our understanding of the mechanisms promoting WGD and its effects is to compare isogenic strains that differ only in their ploidy. Caenorhabditis elegans (C. elegans) is emerging as an animal model for these comparisons, in part because relatively stable and fertile tetraploid strains can be produced rapidly from nearly any diploid strain. Here, we review the use of Caenorhabditis polyploids as tools to understand important developmental processes (e.g., sex determination, dosage compensation, and allometric relationships) and cellular processes (e.g., cell cycle regulation and chromosome dynamics during meiosis). We also discuss how the unique characteristics of the C. elegans WGD model will enable significant advances in our understanding of the mechanisms of polyploidization and its role in development and disease. [ABSTRACT FROM AUTHOR]

The B-cell lymphoma 2 (Bcl-2) family of proteins is the main regulator of apoptosis. However, multiple emerging evidence has revealed that Bcl-2 family proteins are also involved in cellular senescence. On the one hand, the different expression of these proteins determines the entry into senescence. On the other hand, entry into senescence modulates the expression of these proteins, generally conferring resistance to apoptosis. With some exceptions, senescent cells are characterized by the upregulation of antiapoptotic proteins and downregulation of proapoptotic proteins. Under physiological conditions, freshly formed tetraploid cells die by apoptosis due to the tetraploidy checkpoint. However, suppression of Bcl-2 associated x protein (Bax), as well as overexpression of Bcl-2, favors the appearance and survival of tetraploid cells. Furthermore, it is noteworthy that our laboratory has shown that the joint absence of Bax and Bcl-2 antagonist/killer (Bak) favors the entry into senescence of tetraploid cells. Certain microtubule inhibitory chemotherapies, such as taxanes and vinca alkaloids, induce the generation of tetraploid cells. Moreover, the combined use of inhibitors of antiapoptotic proteins of the Bcl-2 family with microtubule inhibitors increases their efficacy. In this review, we aim to shed light on the involvement of the Bcl-2 family of proteins in the senescence program activated after tetraploidization and the possibility of using this knowledge to create a new therapeutic strategy targeting cancer cells. [ABSTRACT FROM AUTHOR]

Median fins are thought to be ancestors of paired fins which in turn give rise to limbs in tetrapods. However, the developmental mechanisms of median fins remain largely unknown. Nonsense mutation of the T-box transcription factor eomesa in zebrafish results in a phenotype without dorsal fin. Compared to zebrafish, the common carp undergo an additional round of whole genome duplication, acquiring an extra copy of protein-coding genes. To verify the function of eomesa genes in common carp, we established a biallelic gene editing technology in this tetraploidy fish through simultaneous disruption of two homologous genes, eomesa1 and eomesa2. We targeted four sites located upstream or within the sequences encoding the T-box domain. Sanger sequencing data indicated the average knockout efficiency was around 40% at T1-T3 sites and 10% at T4 site in embryos at 24 hours post fertilization. The individual editing efficiency was high to about 80% at T1-T3 sites and low to 13.3% at T4 site in larvae at 7 days post fertilization. Among 145 mosaic F0 examined at four months old, three individuals (Mutant 1–3) showed varying degrees of maldevelopment in the dorsal fin and loss of anal fin. Genotyping showed the genomes of all three mutants were disrupted at T3 sites. The null mutation rates on the eomesa1 and eomesa2 loci were 0% and 60% in Mutant 1, 66.7% and 100% in Mutant 2, and 90% and 77.8% in Mutant 3, respectively. In conclusion, we demonstrated a role of eomesa in the formation and development of median fins in Oujiang color common carp and established an method that simultaneously disrupt two homologous genes with one gRNA, which would be useful in genome editing in other polyploidy fishes. [ABSTRACT FROM AUTHOR]

Long‐term disease control in multiple myeloma (MM) is typically an unmet medical need, and most patients experience multiple relapses. Fluorescence in situ hybridization (FISH) is the standard technique to detect chromosomal abnormalities (CAs), which are important to estimate the prognosis of MM and the allocation of risk adapted therapies. In advanced stages, the importance of CAs needs further investigation. From 148 MM patients, two or more paired samples, at least one of which was collected at relapse, were analyzed by FISH. Using targeted next‐generation sequencing, we molecularly investigated samples harboring relapse‐associated CAs. Sixty‐one percent of the patients showed a change in the cytogenetic profile during the disease course, including 10% who acquired high‐risk cytogenetics. Amp(1q) (≥4 copies of 1q21), driven by an additional increase in copy number in patients who already had 3 copies of 1q21, was the most common acquired CA with 16% affected patients. Tetraploidy, found in 10% of the samples collected at the last time‐point, was unstable over the course of the disease and was associated with TP53 lesions. Our results indicate that cytogenetic progression is common in relapsed patients. The relatively high frequency of amp(1q) suggests an active role for this CA in disease progression. [ABSTRACT FROM AUTHOR]

An increase in centrosome number is commonly observed in cancer cells, but the role centrosome amplification plays along with how and when it occurs during cancer development is unclear. One mechanism for generating cancer cells with extra centrosomes is whole genome doubling (WGD), an event that occurs in over 30% of human cancers and is associated with poor survival. Newly formed tetraploid cells can acquire extra centrosomes during WGD, and a generally accepted model proposes that centrosome amplification in tetraploid cells promotes cancer progression by generating aneuploidy and chromosomal instability. Recent findings, however, indicate that newly formed tetraploid cells in vitro lose their extra centrosomes to prevent multipolar cell divisions. Rather than persistent centrosome amplification, this evidence raises the possibility that it may be advantageous for tetraploid cells to initially restore centrosome number homeostasis and for a fraction of the population to reacquire additional centrosomes in the later stages of cancer evolution. In this review, we explore the different evolutionary paths available to newly formed tetraploid cells, their effects on centrosome and chromosome number distribution in daughter cells, and their probabilities of long-term survival. We then discuss the mechanisms that may alter centrosome and chromosome numbers in tetraploid cells and their relevance to cancer progression following WGD.

Chronic inorganic arsenic (iAs) exposure in drinking water is a global issue affecting >225 million people. Skin is a major target organ for iAs. miRNA dysregulation and chromosomal instability (CIN) are proposed mechanisms of iAs-induced carcinogenesis. CIN is a cancer hallmark and tetraploid cells can better tolerate increase in chromosome number and aberration, contributing to the evolution of CIN. miR-186 is overexpressed in iAs-induced squamous cell carcinoma relative to iAs-induced hyperkeratosis. Bioinformatic analysis indicated that miR-186 targets mRNAs of important cell cycle regulators including mitotic checkpoint serine/threonine kinase B (BUB1) and cell division cycle 27 (CDC27). We hypothesized that miR-186 overexpression contributes to iAs-induced transformation of keratinocytes by targeting mitotic regulators leading to induction of CIN. Ker-CT cells, a near diploid human keratinocyte cell line, were transduced with miR-186 overexpressing or scrambled control lentivirus. Stable clones were isolated after puromycin selection. Clones transduced with lentivirus expressing either a scrambled control miRNA or miR-186 were maintained with 0 or 100 nM iAs for 4 weeks. Unexposed scrambled control clones were considered as passage matched controls. Chronic iAs exposure increased miR-186 expression in miR-186 clones. miR-186 overexpression significantly reduced CDC27 levels irrespective of iAs exposure. The percentage of tetraploid or aneuploid cells was increased in iAs exposed miR-186 clones. Aneuploidy can arise from a tetraploid intermediate. Suppression of CDC27 by miR-186 may lead to impairment of mitotic checkpoint complex formation and its ability to maintain cell cycle arrest leading to chromosome misalignment. As a result, cells overexpressing miR-186 and chronically exposed to iAs may have incorrect chromosome segregation and CIN. These data suggest that dysregulation of miRNA by iAs mediates tetraploidy, aneuploidy and chromosomal instability contributing to iAs-induced carcinogenesis.

Aims: Epilepsy is one of the most prevalent neurological diseases. A third of patients with epilepsy remain drug-resistant. The exact aetiology of drug-resistant epilepsy (DRE) is still unknown. Neuronal tetraploidy has been associated with neuropathology. The aim of this study was to assess the presence of tetraploid neurons and astrocytes in DRE. Methods: For that purpose, cortex, hippocampus and amygdala samples were obtained from patients subjected to surgical resection of the epileptogenic zone. Post-mortem brain tissue of subjects without previous records of neurological, neurodegenerative or psychiatric diseases was used as control. Results: The percentage of tetraploid cells was measured by immunostaining of neurons (NeuN) or astrocytes (S100β) followed by flow cytometry analysis. The results were confirmed by image cytometry (ImageStream X Amnis System Cytometer) and with an alternative astrocyte biomarker (NDRG2). Statistical comparison was performed using univariate tests. A total of 22 patients and 10 controls were included. Tetraploid neurons and astrocytes were found both in healthy individuals and DRE patients in the three brain areas analysed: cortex, hippocampus and amygdala. DRE patients presented a higher number of tetraploid neurons (p = 0.020) and astrocytes (p = 0.002) in the hippocampus than controls. These results were validated by image cytometry. Conclusions: We demonstrated the presence of both tetraploid neurons and astrocytes in healthy subjects as well as increased levels of both cell populations in DRE patients. Herein, we describe for the first time the presence of tetraploid astrocytes in healthy subjects. Furthermore, these results provide new insights into epilepsy, opening new avenues for future treatment. [ABSTRACT FROM AUTHOR]

The high-quality genomes and large-scale full-length cDNA sequences of allotetraploid peanuts have been sequenced and released, which has accelerated the functional genomics and molecular breeding research of peanut. In order to understand the difference in the transcriptional levels of wild and cultivated peanuts. In this study, we integrated of second- and third-generation sequencing technologies to sequence full-length transcriptomes in peanut cv. Pingdu9616 and its putative ancestor Arachis monticola. The RNA extracted from six different tissues (i.e., roots, stems, leaves, flowers, needles and pods) were sampled at 20 days after flowering. A total of 31,764 and 33,981 high-quality transcripts were obtained from Monticola and Pingdu9616, respectively. The number of alternative splicing, the unit point mutation of variable adenylation, the number of open reading frames and the two-site mutation were identified in Pingdu9616 more than in Monticola, but the three-site mutation in Pingdu9616 was lower than in Monticola. 1,691 LncRNAs, and 4,000 bp of maximum length of LncRNA was identified in Monticola and Pingdu9616. Furthermore, comparative analysis between transcript data shown that 56 transcription factor families were involved in Monticola, and Pingdu9616 and the number of transcription factors in Pingdu9616 was higher than that in Monticola, the number of expressed genes estimated in flower, root, young pod and leaf organs was higher in Monticola than Pingdu9616. Over all, our study provided a valuable resource of large-scale full-length transcripts for further research of the molecular breeding and functional analysis of genes. [ABSTRACT FROM AUTHOR]

Polyploidy and metastasis are associated with a low probability of disease-free survival in cancer patients. Polyploid cells are known to facilitate tumorigenesis. However, few data associate polyploidization with metastasis. Here, by generating and using diploid (2n) and tetraploid (4n) clones from malignant fibrous histiocytoma (MFH) and colon carcinoma (RKO), we demonstrate the migration and invasion advantage of tetraploid cells in vitro using several assays, including the wound healing, the OrisTM two-dimensional cell migration, single-cell migration tracking by video microscopy, the Boyden chamber, and the xCELLigence RTCA real-time cell migration. Motility advantage was observed despite tetraploid cell proliferation weakness. We could also demonstrate preferential metastatic potential in vivo for the tetraploid clone using the tail vein injection in mice and tracking metastatic tumors in the lung. Using the Mitelman Database of Chromosome Aberrations in Cancer, we found an accumulation of polyploid karyotypes in metastatic tumors compared to primary ones. This work reveals the clinical relevance of the polyploid subpopulation and the strategic need to highlight polyploidy in preclinical studies as a therapeutic target for metastasis.

Cytokinesis, the conclusive act of cell division, allows cytoplasmic organelles and chromosomes to be faithfully partitioned between two daughter cells. In animal organisms, its accurate regulation is a fundamental task for normal development and for preventing aneuploidy. Cytokinesis failures produce genetically unstable tetraploid cells and ultimately result in chromosome instability, a hallmark of cancer cells. In animal cells, the assembly and constriction of an actomyosin ring drive cleavage furrow ingression, resulting in the formation of a cytoplasmic intercellular bridge, which is severed during abscission, the final event of cytokinesis. Kinase-mediated phosphorylation is a crucial process to orchestrate the spatio-temporal regulation of the different stages of cytokinesis. Several kinases have been described in the literature, such as cyclin-dependent kinase, polo-like kinase 1, and Aurora B, regulating both furrow ingression and/or abscission. However, others exist, with well-established roles in cell-cycle progression but whose specific role in cytokinesis has been poorly investigated, leading to considering these kinases as "minor" actors in this process. Yet, they deserve additional attention, as they might disclose unexpected routes of cell division regulation. Here, we summarize the role of multifunctional kinases in cytokinesis with a special focus on those with a still scarcely defined function during cell cleavage. Moreover, we discuss their implication in cancer. [ABSTRACT FROM AUTHOR]

Small molecule inhibitors of aurora kinases are currently being investigated in oncology clinical trials. The long-term effects of these inhibitors on proliferating euploid cells have not been adequately studied. We examined the effect of the reversible pan-aurora kinase inhibitor VX-680 on p53-competent human euploid cells. Circumscribed treatment with VX-680 blocked cytokinesis and arrested cells in G1 or a G1-like status. Approximately 70% of proliferatively arrested cells had 4N DNA content and abnormal nuclei. The remaining 30% of cells possessed 2N DNA content and normal nuclei. The proliferative arrest was not due to the activation of the tumor suppressor Rb and was instead associated with rapid induction of the p53–p21 pathway and p16. The induction was particularly evident in cells with nuclear abnormalities but was independent of activation of the DNA damage response. All of these effects were correlated with the potent inhibition of aurora kinase B. After release from VX-680, the cells with normal nuclei robustly resumed proliferation whereas the cells with abnormal nuclei underwent senescence. Irrespective of their nuclear morphology or DNA content, cells pre-treated with VX-680 failed to grow in soft agar or form tumors in mice. Our findings indicate that an intermittent treatment strategy might minimize the on-target side effects of Aurora Kinase B (AURKB) inhibitory therapies. The strategy allows a significant fraction of dividing normal cells to resume proliferation. [ABSTRACT FROM AUTHOR]

Polyploid plants grow well, are stress tolerant, and are rich in nutrients and bioactive compounds. Thus, they are useful for improving crop quality and yield. In this study, we compared the seed characteristics and metabolite profiles of diploid and tetraploid tartary buckwheat, which was developed via an artificially induced chromosome doubling event. The length, width, area, and thousand-grain weight were greater for the tetraploid seeds than for the diploid seeds. However, the germination rate decreased for the tetraploid seeds. Additionally, there was a gap between the shell and kernel of the tetraploid seeds. Moreover, the water absorption rate was higher for the tetraploid than for the diploid seeds. Chromosome doubling increased the seed total flavonoid content and deepened the seed color. A principal component analysis of the ultrahigh-pressure liquid chromatography-high resolution mass spectrometry data revealed the clear separation between the diploid and tetraploid samples. An orthogonal partial least squares-discriminant analysis and other multivariate statistical analyses identified 83 differentially abundant compounds, with most of the flavonoid metabolites more abundant in the tetraploid than in the diploid seeds. Research on tartary buckwheat polyploidy may result in enhanced germplasm resources and may clarify the mechanism underlying the biosynthesis of bioactive compounds. [ABSTRACT FROM AUTHOR]

A series of polyploidizations in higher-order polyploids is the main event affecting gene content in a genome. Each polyploidization event can lead to massive functional divergence because of the subsequent decrease in selection pressure on duplicated genes; however, the causal relationship between multiple rounds of polyploidization and the functional divergence of duplicated genes is poorly understood. We focused on the Triticum-Aegilops complex lineage and compared selection pressure before and after tetraploidization and hexaploidization events. Although both events led to decreased selection pressure on homoeologous gene pairs (compared with diploids and tetraploids), the initial tetraploidization had a greater impact on selection pressure on homoeologous gene pairs than did subsequent hexaploidization. Consistent with this, selection pressure on expression patterns for the initial event relaxed more than those for the subsequent event. Surprisingly, the decreased selection pressure on these homoeologous genes was independent of the existence of in-paralogs within the same subgenome. Wheat homoeologous pairs had different evolutionary consequences compared with orthologs related to other mechanisms (ancient allopolyploidization, ancient autopolyploidization, and small-scale duplication). Furthermore, tetraploidization and hexaploidization also seemed to have different evolutionary consequences. This suggests that homoeologous genes retain unique functions, including functions that are unlikely to be preserved in genes generated by the other duplication mechanisms. We found that their unique functions differed between tetraploidization and hexaploidization (e.g., reproductive and chromosome segregation processes). These findings imply that the substantial number of gene pairs resulting from multiple allopolyploidization events, especially initial tetraploidization, may have been a unique source of functional divergence., (© 2024 The Author(s). The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)

Early studies of the textbook mixed-ploidy system Biscutella laevigata highlighted diploids restricted to never-glaciated lowlands and tetraploids at high elevations across the European Alps, promoting the hypothesis that whole-genome duplication (WGD) is advantageous under environmental changes. Here we addressed long-held hypotheses on the role of hybridisation at the origin of the tetraploids, their single vs multiple origins, and whether a shift in climatic niche accompanied WGD. Climatic niche modelling together with spatial genetics and coalescent modelling based on ddRAD-seq genotyping of 17 diploid and 19 tetraploid populations was used to revisit the evolution of this species complex in space and time. Diploids differentiated into four genetic lineages corresponding to allopatric glacial refugia at the onset of the last ice age, whereas tetraploids displaying tetrasomic inheritance formed a uniform group that originated from southern diploids before the last glacial maximum. Derived from diploids occurring at high elevation, autotetraploids likely inherited their adaptation to high elevation rather than having evolved it through or after WGD. They further presented considerable postglacial expansion across the Alps and underwent admixture with diploids. Although the underpinnings of the successful expansion of autotetraploids remain elusive, differentiation in B. laevigata was chiefly driven by the glacial history of the Alps., (© 2024 The Author(s). New Phytologist © 2024 New Phytologist Foundation.)

We present the case of a girl with complete tetraploidy who has survived to her present age of 4 years and 1 month. Infants with complete tetraploidy have been described to have a limited lifespan owing to complications. We report her characteristics, medical history, and development., (© 2024 The Author(s). American Journal of Medical Genetics Part A published by Wiley Periodicals LLC.)

Autotetraploid Carassius auratus is a stable hereditary autotetraploid fish resulting from the hybridization of Carassius auratus red var. (RCC, ♀) × Megalobrama amblycephala (BSB, ♂), containing four sets of RCC chromosomes. However, the molecular mechanism underlying the determination of sex in this species remains largely unknown. Currently, there lacks a full understanding of the molecular mechanisms governing sex determination and specific molecular markers to differentiate sex in this species. In this study, 25,801,677 SNPs (Single-nucleotide polymorphism) and 6,210,306 Indels (insertion-deletion) were obtained from whole-genome resequencing of 100 individuals (including 50 female and 50 male). Further identification confirmed the candidate chromosomes as Chr46B, with the sex-determining region located at Chr46B: 22,500,000-22,800,000 bp. Based on the male-specific insertion (26 bp) within the candidate sex-determining region, a pair of sex-specific molecular markers has been identified. In addition, based on the screening of candidate sex-determining region genes and RT-qPCR validation analysis, ADAM10, AQP9 and tc1a were identified as candidate sex-determining genes. These findings provide a robust foundation for investigating sex determination mechanisms in fish, the evolution of sex chromosomes, and the development of monosex populations., (© 2024. Science China Press.)

Background: Fusarium head blight (FHB), a devastating disease of wheat production, is predominantly elicited by Fusarium graminearum (Fg). The tetraploid Thinopyrum elongatum is a tertiary gene resource of common wheat that possesses high affinity and displays high resistance traits against multiple biotic and abiotic stress. We aim to employ and utilize the novel FHB resistance resources from the wild germplasm of common wheat for breeding., Results: Durum wheat-tetraploid Th. elongatum amphiploid 8801 was hybridized with common wheat cultivars SM482 and SM51, and the F 5 generation was generated. We conducted cytogenetically in situ hybridization (ISH) technologies to select and confirm a genetically stable 7E(7D) substitution line K17-1069-5, which showed FHB expansion resistance in both field and greenhouse infection experiments and displayed no significant disadvantage in agronomic traits compared to their common wheat parents in the field. The F 2 segregation populations (K17-1069-5 × SM830) showed that the 7E chromosome conferred dominant FHB resistance with dosage effect. We developed 19 SSR molecular markers specific to chromosome 7E, which could be conducted for genetic mapping and large breeding populations marker-assisted selection (MAS) during selection procedures in the future. We isolated a novel Fhb7 allele from the tetraploid Th. elongatum chromosome 7E (Chr7E) using homology-based cloning, which was designated as TTE7E-Fhb7., Conclusions: In summary, our study developed a novel wheat-tetraploid Thinopyrum elongatum 7E(7D) K17-1069-5 substitution line which contains stable FHB resistance., (© 2024. The Author(s).)

Plant Snakin/GASA and defensin peptides are cysteine-rich molecules with a wide range of biological functions. They are included within the large family of plant antimicrobial peptides (AMPs), characterized by their structural stability, broad spectrum of activity, and diverse mechanisms of action. The Dilatata group of Paspalum includes five allotetraploids that share an equivalent genomic formula IIJJ. From RNA-seq data of seedling tissues, we performed an in silico characterization of the defensin and Snakin/GASA genes in these species and diploids with a II and JJ genome formula and studied the evolutionary consequences of polyploidy on the expression of the two AMPs families. A total of 107 defensins (distributed in eight groups) and 145 Snakin/GASA (grouped in three subfamilies) genes were identified. Deletions, duplications and/or gene silencing seem to have mediated the evolution of these genes in the allotetraploid species. In defensin genes, the IIJJ allopolyploids retained the I subgenome defensin copies in some of the identified groups supporting the closeness of their nuclear genome with the I subgenome species. In both AMPs families, orthologous genes in tetraploids exhibit higher similarity to each other than with diploids. This data supports the theory of a single origin for the allotetraploids. Several copies of both defensin and Snakin/GASA genes were detected in the five polyploids which could have arisen due to duplication events occurring independently during the diploidization processes in the allotetraploid taxa., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Key Message: Two small fragment translocation lines (T4DS·4DL-4EL and T5AS·5AL-4EL) showed high resistance to stripe rust and resistance gene Yr4EL was localized to an about 35 Mb region at the end of chr arm 4EL. Stripe rust, caused by the fungus Puccinia striiformis f. sp. tritici, is a devastating wheat disease worldwide. Deployment of disease resistance (R) genes in wheat cultivars is the most effective way to control the disease. Previously, the all-stage stripe rust R gene Yr4EL from tetraploid Thinopyrum elongatum was introduced into common wheat as 4E(4D) substitution and T4DS·4EL translocation lines. To further map and utilize Yr4EL, Chinese Spring (CS) mutant pairing homoeologous gene ph1b was used in crossing to induce recombination between chromosome (chr) 4EL and wheat chromosomes. Two small fragment translocation lines T4DS·4DL-4EL and T5AS·5AL-4EL with Yr4EL resistance were selected using molecular markers and confirmed by genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), and Wheat 660 K SNP array analyses. We mapped Yr4EL to an about 35 Mb region at the end of chr 4EL, corresponding to 577.76-612.97 Mb based on the diploid Th. elongatum reference genome. In addition, two competitive allele-specific PCR (KASP) markers co-segregating with Yr4EL were developed to facilitate molecular marker-assisted selection in breeding. The T4DS·4DL-4EL lines were crossed and backcrossed with wheat cultivars SM482 and CM42, and the resulting pre-breeding lines showed high stripe rust resistance and potential for wheat breeding with good agronomic traits. These lines represent new germplasm for wheat stripe rust resistance breeding, as well as providing a solid foundation for Yr4EL fine mapping and cloning., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)