A route to de novo domestication of wild allotetraploid rice.

Cultivated rice varieties are all diploid, and polyploidization of rice has long been desired because of its advantages in genome buffering, vigorousness, and environmental robustness. However, a workable route remains elusive. Here, we describe a practical strategy, namely de novo domestication of wild allotetraploid rice. By screening allotetraploid wild rice inventory, we identified one genotype of Oryza alta (CCDD), polyploid rice 1 (PPR1), and established two important resources for its de novo domestication: (1) an efficient tissue culture, transformation, and genome editing system and (2) a high-quality genome assembly discriminated into two subgenomes of 12 chromosomes apiece. With these resources, we show that six agronomically important traits could be rapidly improved by editing O. alta homologs of the genes controlling these traits in diploid rice. Our results demonstrate the possibility that de novo domesticated allotetraploid rice can be developed into a new staple cereal to strengthen world food security.

Whole-genome doubling in tissues and tumors.

The overwhelming majority of proliferating somatic human cells are diploid, and this genomic state is typically maintained across successive cell divisions. However, failures in cell division can induce a whole-genome doubling (WGD) event, in which diploid cells transition to a tetraploid state. While some WGDs are developmentally programmed to produce nonproliferative tetraploid cells with specific cellular functions, unscheduled WGDs can be catastrophic: erroneously arising tetraploid cells are ill-equipped to cope with their doubled cellular and chromosomal content and quickly become genomically unstable and tumorigenic. Deciphering the genetics that underlie the genesis, physiology, and evolution of whole-genome doubled (WGD+) cells may therefore reveal therapeutic avenues to selectively eliminate pathological WGD+ cells.

The exceptional form and function of the giant bacterium Ca. Epulopiscium viviparus revolves around its sodium motive force.

Epulopiscium spp. are the largest known heterotrophic bacteria; a large cigar-shaped individual is a million times the volume of Escherichia coli. To better understand the metabolic potential and relationship of Epulopiscium sp. type B with its host Naso tonganus, we generated a high-quality draft genome from a population of cells taken from a single fish. We propose the name Candidatus Epulopiscium viviparus to describe populations of this best-characterized Epulopiscium species. Metabolic reconstruction reveals more than 5% of the genome codes for carbohydrate active enzymes, which likely degrade recalcitrant host-diet algal polysaccharides into substrates that may be fermented to acetate, the most abundant short-chain fatty acid in the intestinal tract. Moreover, transcriptome analyses and the concentration of sodium ions in the host intestinal tract suggest that the use of a sodium motive force (SMF) to drive ATP synthesis and flagellar rotation is integral to symbiont metabolism and cellular biology. In natural populations, genes encoding both F-type and V-type ATPases and SMF generation via oxaloacetate decarboxylation are among the most highly expressed, suggesting that ATPases synthesize ATP and balance ion concentrations across the cell membrane. High expression of these and other integral membrane proteins may allow for the growth of its extensive intracellular membrane system. Further, complementary metabolism between microbe and host is implied with the potential provision of nitrogen and B vitamins to reinforce this nutritional symbiosis. The few features shared by all bacterial behemoths include extreme polyploidy, polyphosphate synthesis, and thus far, they have all resisted cultivation in the lab.

Non-B-form DNA tends to form in centromeric regions and has undergone changes in polyploid oat subgenomes.

Centromeres are the specialized regions of the chromosomes that direct faithful chromosome segregation during cell division. Despite their functional conservation, centromeres display features of rapidly evolving DNA and wide evolutionary diversity in size and organization. Previous work found that the noncanonical B-form DNA structures are abundant in the centromeres of several eukaryotic species with a possible implication for centromere specification. Thus far, systematic studies into the organization and function of non-B-form DNA in plants remain scarce. Here, we applied the oat system to investigate the role of non-B-form DNA in centromeres. We conducted chromatin immunoprecipitation sequencing using an antibody to the centromere-specific histone H3 variant (CENH3); this accurately positioned oat centromeres with different ploidy levels and identified a series of centromere-specific sequences including minisatellites and retrotransposons. To define genetic characteristics of oat centromeres, we surveyed the repeat sequences and found that dyad symmetries were abundant in oat centromeres and were predicted to form non-B-DNA structures in vivo. These structures including bent DNA, slipped DNA, Z-DNA, G-quadruplexes, and R-loops were prone to form within CENH3-binding regions. Dynamic conformational changes of predicted non-B-DNA occurred during the evolution from diploid to tetraploid to hexaploid oat. Furthermore, we applied the single-molecule technique of AFM and DNA:RNA immunoprecipitation with deep sequencing to validate R-loop enrichment in oat centromeres. Centromeric retrotransposons exhibited strong associations with R-loop formation. Taken together, our study elucidates the fundamental character of non-B-form DNA in the oat genome and reveals its potential role in centromeres.

Whole-genome sequencing of allotetraploid bermudagrass reveals the origin of Cynodon and candidate genes for salt tolerance.

Bermudagrass (Cynodon dactylon) is a globally distributed, extensively used warm-season turf and forage grass with high tolerance to salinity and drought stress in alkaline environments. However, the origin of the species and genetic mechanisms for salinity tolerance in the species are basically unknown. Accordingly, we set out to study evolution divergence events in the Cynodon genome and to identify genes for salinity tolerance. We developed a 604.0 Mb chromosome-level polyploid genome sequence for bermudagrass 'A12359' (n = 18). The C. dactylon genome comprises 2 complete sets of homoeologous chromosomes, each with approximately 30 000 genes, and most genes are conserved as syntenic pairs. Phylogenetic study showed that the initial Cynodon species diverged from Oropetium thomaeum approximately 19.7-25.4 million years ago (Mya), the A and B subgenomes of C. dactylon diverged approximately 6.3-9.1 Mya, and the bermudagrass polyploidization event occurred 1.5 Mya on the African continent. Moreover, we identified 82 candidate genes associated with seven agronomic traits using a genome-wide association study, and three single-nucleotide polymorphisms were strongly associated with three salt resistance genes: RAP2-2, CNG channels, and F14D7.1. These genes may be associated with enhanced bermudagrass salt tolerance. These bermudagrass genomic resources, when integrated, may provide fundamental insights into evolution of diploid and tetraploid genomes and enhance the efficacy of comparative genomics in studying salt tolerance in Cynodon.

Whole-chromosome oligo-painting in licorice unveils interspecific chromosomal evolutionary relationships and possible origin of triploid genome species.

Licorice is one of the most extensively studied medicinal plants in the world, whose roots and rhizomes have long been used as both a sweetener and an essential component in numerous herbal preparations. However, the genus Glycyrrhiza has a complex composition, and the interspecies chromosomal relationships, origin, and evolution are still largely unclear. Here, we develop a set of whole-chromosome painting probes that allowed identification of all eight chromosomes of licorice on same metaphase chromosomes. Comparative chromosome painting analyses in seven different Glycyrrhiza species revealed that the genus Glycyrrhiza maintained extraordinarily conserved chromosomal synteny after about 3-12 million years of divergence. No cytologically visible inter-chromosomal rearrangements were identified in any species. By comparative chromosomal karyotype analyses, we revealed interspecific chromosome evolutionary relationships and dramatic variable chromosomal karyotype after independent divergence and demonstrated that G. prostrate was the most closely related to the ancestral type among the seven Glycyrrhiza species. Furthermore, we also discovered a G. glandulosa seed with distinct triploid-genome for the first time in China, suggesting the existence of a polyploid evolutionary pathway in the genus Glycyrrhiza, which challenges the previous notion that only diploids of licorice existed in nature. This study expands our knowledge of the chromosome evolution of licorice and will lay an important foundation for the genome origin and evolution studies in the genus Glycyrrhiza.

Novel centromeric repetitive DNA elements reveal karyotype dynamics in polyploid sainfoin (Onobrychis viciifolia).

Polyploidy is a common feature in eukaryotes with one of paramount consequences leading to better environmental adaptation. Heterochromatin is often located at telomeres and centromeres and contains repetitive DNA sequences. Sainfoin (Onobrychis viciifolia) is an important perennial forage legume for sustainable agriculture. However, there are only a few studies on the sainfoin genome and chromosomes. In this study, novel tandem repetitive DNA sequences of the sainfoin genome (OnVi180, OnVi169, OnVi176 and OnVidimer) were characterized using bioinformatics, molecular and cytogenetic approaches. The OnVi180 and OnVi169 elements colocalized within functional centromeres. The OnVi176 and OnVidimer elements were localized in centromeric, subtelomeric and interstitial regions. We constructed a sainfoin karyotype that distinguishes the seven basic chromosome groups. Our study provides the first detailed description of heterochromatin and chromosome structure of sainfoin and proposes an origin of heterozygous ancestral genomes, possibly from the same ancestral diploid species, not necessarily from different species, or for chromosome rearrangements after polyploidy. Overall, we discuss our novel and complementary findings in a polyploid crop with unique and complex chromosomal features.

Combining Traditional Mutagenesis with New High-Throughput Sequencing and Genome Editing to Reveal Hidden Variation in Polyploid Wheat.

Induced mutations have been used to generate novel variation for breeding purposes since the early 1900s. However, the combination of this old technology with the new capabilities of high-throughput sequencing has resulted in powerful reverse genetic approaches in polyploid crops. Sequencing genomes or exomes of large mutant populations can generate extensive databases of mutations for most genes. These mutant collections, together with genome editing, are being used in polyploid species to combine mutations in all copies of a gene (homoeologs), and to expose phenotypic variation that was previously hidden by functional redundancy among homoeologs. This redundancy is more extensive in recently formed polyploids such as wheat, which can now benefit from the deployment of useful recessive mutations previously identified in its diploid relatives. Sequenced mutant populations and genome editing have changed the paradigm of what is possible in functional genetic analysis of wheat.

Complex Polyploids: Origins, Genomic Composition, and Role of Introgressed Alleles.

Introgression allows polyploid species to acquire new genomic content from diploid progenitors or from other unrelated diploid or polyploid lineages, contributing to genetic diversity and facilitating adaptive allele discovery. In some cases, high levels of introgression elicit the replacement of large numbers of alleles inherited from the polyploid's ancestral species, profoundly reshaping the polyploid's genomic composition. In such complex polyploids, it is often difficult to determine which taxa were the progenitor species and which taxa provided additional introgressive blocks through subsequent hybridization. Here, we use population-level genomic data to reconstruct the phylogenetic history of Betula pubescens (downy birch), a tetraploid species often assumed to be of allopolyploid origin and which is known to hybridize with at least four other birch species. This was achieved by modeling polyploidization and introgression events under the multispecies coalescent and then using an approximate Bayesian computation rejection algorithm to evaluate and compare competing polyploidization models. We provide evidence that B. pubescens is the outcome of an autoploid genome doubling event in the common ancestor of B. pendula and its extant sister species, B. platyphylla, that took place approximately 178,000-188,000 generations ago. Extensive hybridization with B. pendula, B. nana, and B. humilis followed in the aftermath of autopolyploidization, with the relative contribution of each of these species to the B. pubescens genome varying markedly across the species' range. Functional analysis of B. pubescens loci containing alleles introgressed from B. nana identified multiple genes involved in climate adaptation, while loci containing alleles derived from B. humilis revealed several genes involved in the regulation of meiotic stability and pollen viability in plant species.

Evolutionary divergence of duplicated genomes in newly described allotetraploid cottons.

Allotetraploid cotton (Gossypium) species represents a model system for the study of plant polyploidy, molecular evolution, and domestication. Here, chromosome-scale genome sequences were obtained and assembled for two recently described wild species of tetraploid cotton, Gossypium ekmanianum [(AD)6, Ge] and Gossypium stephensii [(AD)7, Gs], and one early form of domesticated Gossypium hirsutum, race punctatum [(AD)1, Ghp]. Based on phylogenomic analysis, we provide a dated whole-genome level perspective for the evolution of the tetraploid Gossypium clade and resolved the evolutionary relationships of Gs, Ge, and domesticated G. hirsutum. We describe genomic structural variation that arose during Gossypium evolution and describe its correlates-including phenotypic differentiation, genetic isolation, and genetic convergence-that contributed to cotton biodiversity and cotton domestication. Presence/absence variation is prominent in causing cotton genomic structural variations. A presence/absence variation-derived gene encoding a phosphopeptide-binding protein is implicated in increasing fiber length during cotton domestication. The relatively unimproved Ghp offers the potential for gene discovery related to adaptation to environmental challenges. Expanded gene families enoyl-CoA δ isomerase 3 and RAP2-7 may have contributed to abiotic stress tolerance, possibly by targeting plant hormone-associated biochemical pathways. Our results generate a genomic context for a better understanding of cotton evolution and for agriculture.

The midgut epithelium of mosquitoes adjusts cell proliferation and endoreplication to respond to physiological challenges.

BACKGROUND: Hematophagous mosquitoes transmit many pathogens that cause human diseases. Pathogen acquisition and transmission occur when female mosquitoes blood feed to acquire nutrients for reproduction. The midgut epithelium of mosquitoes serves as the point of entry for transmissible viruses and parasites. RESULTS: We studied midgut epithelial dynamics in five major mosquito vector species by quantifying PH3-positive cells (indicative of mitotic proliferation), the incorporation of nucleotide analogs (indicative of DNA synthesis accompanying proliferation and/or endoreplication), and the ploidy (by flow cytometry) of cell populations in the posterior midgut epithelium of adult females. Our results show that the epithelial dynamics of post-emergence maturation and of mature sugar-fed guts were similar in members of the Aedes, Culex, and Anopheles genera. In the first three days post-emergence, ~ 20% of cells in the posterior midgut region of interest incorporated nucleotide analogs, concurrent with both proliferative activity and a broad shift toward higher ploidy. In mature mosquitoes maintained on sugar, an average of 3.5% of cells in the posterior midgut region of interest incorporated nucleotide analogs from five to eight days post-emergence, with a consistent presence of mitotic cells indicating constant cell turnover. Oral bacterial infection triggered a sharp increase in mitosis and nucleotide analog incorporation, suggesting that the mosquito midgut undergoes accelerated cellular turnover in response to damage. Finally, blood feeding resulted in an increase in cell proliferation, but the nature and intensity of the response varied by mosquito species and by blood source (human, bovine, avian or artificial). In An. gambiae, enterocytes appeared to reenter the cell cycle to increase ploidy after consuming blood from all sources except avian. CONCLUSIONS: We saw that epithelial proliferation, differentiation, and endoreplication reshape the blood-fed gut to increase ploidy, possibly to facilitate increased metabolic activity. Our results highlight the plasticity of the midgut epithelium in mosquitoes' physiological responses to distinct challenges.

Biased mutations and gene losses underlying diploidization of the tetraploid broomcorn millet genome.

Broomcorn millet (Panicum miliaceum L.) is one of the earliest domesticated crops, and is a valuable resource to secure food diversity and combat drought stresses under the global warming scenario. However, due to the absence of extant diploid progenitors, the polyploidy genome of broomcorn millet remains poorly understood. Here, we report the chromosome-scale genome assembly of broomcorn millet. We divided the broomcorn millet genome into two subgenomes using the genome sequence of Panicum hallii, a diploid relative of broomcorn millet. Our analyses revealed that the two subgenomes diverged at ~4.8 million years ago (Mya), while the allotetraploidization of broomcorn millet may have occurred about ~0.48 Mya, suggesting that broomcorn millet is a relatively recent allotetraploid. Comparative analyses showed that subgenome B was larger than subgenome A in size, which was caused by the biased accumulation of long terminal repeat retrotransposons in the progenitor of subgenome B before polyploidization. Notably, the accumulation of biased mutations in the transposable element-rich subgenome B led to more gene losses. Although no significant dominance of either subgenome was observed in the expression profiles of broomcorn millet, we found the minimally expressed genes in P. hallii tended to be lost during diploidization of broomcorn millet. These results suggest that broomcorn millet is at the early stage of diploidization and that mutations likely occurred more on genes that were marked with lower expression levels.

Changing the Landscape of Solid Tumor Therapy from Apoptosis-Promoting to Apoptosis-Inhibiting Strategies.

The many limitations of implementing anticancer strategies under the term "precision oncology" have been extensively discussed. While some authors propose promising future directions, others are less optimistic and use phrases such as illusion, hype, and false hypotheses. The reality is revealed by practicing clinicians and cancer patients in various online publications, one of which has stated that "in the quest for the next cancer cure, few researchers bother to look back at the graveyard of failed medicines to figure out what went wrong". The message is clear: Novel therapeutic strategies with catchy names (e.g., synthetic "lethality") have not fulfilled their promises despite decades of extensive research and clinical trials. The main purpose of this review is to discuss key challenges in solid tumor therapy that surprisingly continue to be overlooked by the Nomenclature Committee on Cell Death (NCCD) and numerous other authors. These challenges include: The impact of chemotherapy-induced genome chaos (e.g., multinucleation) on resistance and relapse, oncogenic function of caspase 3, cancer cell anastasis (recovery from late stages of apoptosis), and pitfalls of ubiquitously used preclinical chemosensitivity assays (e.g., cell "viability" and tumor growth delay studies in live animals) that score such pro-survival responses as "lethal" events. The studies outlined herein underscore the need for new directions in the management of solid tumors.

Recursive Test of Hardy-Weinberg Equilibrium in Tetraploids.

Testing for deviations from Hardy-Weinberg equilibrium (HWE) can provide fundamental information about genetic variation and evolutionary processes in natural populations. In contrast to diploids, where genotype frequencies remain constant after a single episode of random mating, polyploids, characterized by polysomic inheritance, approach HWE gradually. Here, we mathematically show the asymptotic trajectory of tetraploid equilibrium from any initial genotype frequencies. We formulate a statistical framework to test and estimate the degree of deviation from HWE at individual loci in allotetraploids and autotetraploids. Knowledge about HWE test fills an important gap in population genetic studies of tetraploids related to their evolution and ecology.

Integrative analyses of long and short-read RNA sequencing reveal the spliced isoform regulatory network of seedling growth dynamics in upland cotton.

The polyploid genome of cotton has significantly increased the transcript complexity. Recent advances in full-length transcript sequencing are now widely used to characterize the complete landscape of transcriptional events. Such studies in cotton can help us to explore the genetic mechanisms of the cotton seedling growth. Through long-read single-molecule RNA sequencing, this study compared the transcriptomes of three yield contrasting genotypes of upland cotton. Our analysis identified different numbers of spliced isoforms from 31,166, 28,716, and 28,713 genes in SJ48, Z98, and DT8 cotton genotypes, respectively, most of which were novel compared to previous cotton reference transcriptomes, and showed significant differences in the number of exon structures and coding sequence length due to intron retention. Quantification of isoform expression revealed significant differences in expression in the root and leaf of each genotype. An array of key isoform target genes showed protein kinase or phosphorylation functions, and their protein interaction network contained most of the circadian oscillator proteins. Spliced isoforms from the GIGANTEA (GI) protien were differentially regulated in each genotype and might be expected to regulate translational activities, including the sequence and function of target proteins. In addition, these spliced isoforms generate diurnal expression profiles in cotton leaves, which may alter the transcriptional regulatory network of seedling growth. Silencing of the novel spliced GI isoform Gh_A02G0645_N17 significantly affected biomass traits, contributed to variable growth, and increased transcription of the early flowering pathway gene ELF in cotton. Our high-throughput hybrid sequencing results will be useful to dissect functional differences among spliced isoforms in the polyploid cotton genome.

Synthetically induced Arabidopsis thaliana autotetraploids provide insights into the analysis of meiotic mutants with altered crossover frequency.

Mutations affecting crossover (CO) frequency and distribution lead to the presence of univalents during meiosis, giving rise to aneuploid gametes and sterility. These mutations may have a different effect after chromosome doubling. The combination of altered ploidy and mutations could be potentially useful to gain new insights into the mechanisms and regulation of meiotic recombination; however, studies using autopolyploid meiotic mutants are scarce. Here, we have analyzed the cytogenetic consequences in colchicine-induced autotetraploids (colchiploids) from different Arabidopsis mutants with an altered CO frequency. We have found that there are three types of mutants: mutants in which chiasma frequency is doubled after chromosome duplication (zip4, mus81), as in the control; mutants in which polyploidy leads to a higher-than-expected increase in chiasma frequency (asy1, mer3, hei10, and mlh3); and mutants in which the rise in chiasma frequency produced by the presence of two extrachromosomal sets is less than doubled (msh5, fancm). In addition, the proportion of class I/class II COs varies after chromosome duplication in the control. The results obtained reveal the potential of colchiploid meiotic mutants for better understanding of the function of key proteins during plant meiosis. This is especially relevant considering that most crops are polyploids.

Phylogenomic analyses re-examine the evolution of reinforcement and hypothesized hybrid speciation in Phlox wildflowers.

The tree of life is riddled with reticulate evolutionary histories, and some clades, such as the eastern standing Phlox, appear to be hotspots of hybridization. In this group, there are two cases of reinforcement and nine hypothesized hybrid species. Given their historical importance in our understanding of plant speciation, the relationships between these taxa and the role of hybridization in their diversification require genomic validation. Using phylogenomic analyses, we resolve the evolutionary relationships of the eastern standing Phlox and evaluate hypotheses about whether and how hybridization and gene flow played a role in their diversification. Our results provide novel resolution of the phylogenetic relationships in this group, including paraphyly across some taxa. We identify gene flow during one case of reinforcement and find genomic support for a hybrid lineage underlying one of the five hypothesized homoploid hybrid speciation events. Additionally, we estimate the ancestries of four allotetraploid hybrid species. Our results are consistent with hybridization contributing to diverse evolutionary outcomes within this group; although, not as extensively as previously hypothesized. This study demonstrates the importance of phylogenomics in evaluating hypothesized evolutionary histories of non-model systems and adds to the growing support of interspecific genetic exchange in the generation of biodiversity.

Homoeologous crossovers are distally biased and underlie genomic instability in first-generation neo-allopolyploid Arabidopsis suecica.

First-generation polyploids often suffer from more meiotic errors and lower fertility than established wild polyploid populations. One such example is the allopolyploid model species Arabidopsis suecica which originated c. 16 000 generations ago. We present here a comparison of meiosis and its outcomes in naturally evolved and first-generation 'synthetic' A. suecica using a combination of cytological and genomic approaches. We show that while meiosis in natural lines is largely diploid-like, synthetic lines have high levels of meiotic errors including incomplete synapsis and nonhomologous crossover formation. Whole-genome re-sequencing of progeny revealed 20-fold higher levels of homoeologous exchange and eightfold higher aneuploidy originating from synthetic parents. Homoeologous exchanges showed a strong distal bias and occurred predominantly in genes, regularly generating novel protein variants. We also observed that homoeologous exchanges can generate megabase scale INDELs when occurring in regions of inverted synteny. Finally, we observed evidence of sex-specific differences in adaptation to polyploidy with higher success in reciprocal crosses to natural lines when synthetic plants were used as the female parent. Our results directly link cytological phenotypes in A. suecica with their genomic outcomes, demonstrating that homoeologous crossovers underlie genomic instability in neo-allopolyploids and are more distally biased than homologous crossovers.

MYC2 regulates stomatal density and water use efficiency via targeting EPF2/EPFL4/EPFL9 in poplar.

Although polyploid plants have lower stomatal density than their diploid counterparts, the molecular mechanisms underlying this difference remain elusive. Here, we constructed a network based on the triploid poplar transcriptome data and triple-gene mutual interaction algorithm and found that PpnMYC2 was related to stomatal development-related genes PpnEPF2, PpnEPFL4, and PpnEPFL9. The interactions between PpnMYC2 and PagJAZs were experimentally validated. PpnMYC2-overexpressing poplar and Arabidopsis thaliana had reduced stomatal density. Poplar overexpressing PpnMYC2 had higher water use efficiency and drought resistance. RNA-sequencing data of poplars overexpressing PpnMYC2 showed that PpnMYC2 promotes the expression of stomatal density inhibitors PagEPF2 and PagEPFL4 and inhibits the expression of the stomatal density-positive regulator PagEPFL9. Yeast one-hybrid system, electrophoretic mobility shift assay, ChIP-qPCR, and dual-luciferase assay were employed to substantiate that PpnMYC2 directly regulated PagEPF2, PagEPFL4, and PagEPFL9. PpnMYC2, PpnEPF2, and PpnEPFL4 were significantly upregulated, whereas PpnEPFL9 was downregulated during stomatal formation in triploid poplar. Our results are of great significance for revealing the regulation mechanism of plant stomatal occurrence and polyploid stomatal density, as well as reducing stomatal density and improving plant water use efficiency by overexpressing MYC2.

FIGL1 prevents aberrant chromosome associations and fragmentation and limits crossovers in polyploid wheat meiosis.

Meiotic crossovers (COs) generate genetic diversity and are crucial for viable gamete production. Plant COs are typically limited to 1-3 per chromosome pair, constraining the development of improved varieties, which in wheat is exacerbated by an extreme distal localisation bias. Advances in wheat genomics and related technologies provide new opportunities to investigate, and possibly modify, recombination in this important crop species. Here, we investigate the disruption of FIGL1 in tetraploid and hexaploid wheat as a potential strategy for modifying CO frequency/position. We analysed figl1 mutants and virus-induced gene silencing lines cytogenetically. Genetic mapping was performed in the hexaploid. FIGL1 prevents abnormal meiotic chromosome associations/fragmentation in both ploidies. It suppresses class II COs in the tetraploid such that CO/chiasma frequency increased 2.1-fold in a figl1 msh5 quadruple mutant compared with a msh5 double mutant. It does not appear to affect class I COs based on HEI10 foci counts in a hexaploid figl1 triple mutant. Genetic mapping in the triple mutant suggested no significant overall increase in total recombination across examined intervals but revealed large increases in specific individual intervals. Notably, the tetraploid figl1 double mutant was sterile but the hexaploid triple mutant was moderately fertile, indicating potential utility for wheat breeding.