Chromosome stability of synthetic Triticum turgidum-Aegilops umbellulata hybrids.

BACKGROUND: Unreduced gamete formation during meiosis plays a critical role in natural polyploidization. However, the unreduced gamete formation mechanisms in Triticum turgidum-Aegilops umbellulata triploid F1 hybrid crosses and the chromsome numbers and compostions in T. turgidum-Ae. umbellulata F2 still not known. RESULTS: In this study, 11 T.turgidum-Ae. umbellulata triploid F1 hybrid crosses were produced by distant hybridization. All of the triploid F1 hybrids had 21 chromosomes and two basic pathways of meiotic restitution, namely first-division restitution (FDR) and single-division meiosis (SDM). Only FDR was found in six of the 11 crosses, while both FDR and SDM occurred in the remaining five crosses. The chromosome numbers in the 127 selfed F2 seeds from the triploid F1 hybrid plants of 10 crosses (no F2 seeds for STU 16) varied from 35 to 43, and the proportions of euploid and aneuploid F2 plants were 49.61% and 50.39%, respectively. In the aneuploid F2 plants, the frequency of chromosome loss/gain varied among genomes. The chromosome loss of the U genome was the highest (26.77%) among the three genomes, followed by that of the B (22.83%) and A (11.81%) genomes, and the chromosome gain for the A, B, and U genomes was 3.94%, 3.94%, and 1.57%, respectively. Of the 21 chromosomes, 7U (16.54%), 5 A (3.94%), and 1B (9.45%) had the highest loss frequency among the U, A, and B genomes. In addition to chromosome loss, seven chromosomes, namely 1 A, 3 A, 5 A, 6 A, 1B, 1U, and 6U, were gained in the aneuploids. CONCLUSION: In the aneuploid F2 plants, the frequency of chromosome loss/gain varied among genomes, chromsomes, and crosses. In addition to variations in chromosome numbers, three types of chromosome translocations including 3UL·2AS, 6UL·1AL, and 4US·6AL were identified in the F2 plants. Furthermore, polymorphic fluorescence in situ hybridization karyotypes for all the U chromosomes were also identified in the F2 plants when compared with the Ae. umbellulata parents. These results provide useful information for our understanding the naturally occurred T. turgidum-Ae. umbellulata amphidiploids.

Molecular and cytogenetic analyses in Geranium macrorrhizum L. wild Italian plants.

Geranium macrorrhizum L. is a herbaceous species native to southern Europe and was introduced in central Europe and North America. It is also widely distributed in Italy. In this study, molecular and cytogenetic analyses were carried out on 22 wild plants, collected in central and southern Italy, compared with five cultivated plants, with the main purpose to identify those living near the Marmore waterfalls in central Italy, recently described as the new species Geranium lucarinii. Four barcoding markers (rbcL, matK, trnH-psbA intergenic spacer and internal transcribed spacer region) were sequenced and their variability among the plants was evaluated. Chromosome numbers were determined and 45S rDNA was physically mapped by fluorescence in situ hybridization. Moreover, genomic affinity between wild and cultivated plants was evaluated by genomic in situ hybridization. The results of this study supported that all the plants belong to G. macrorrhizum, including the Marmore population. Barcoding analyses showed a close similarity among the wild plants, and a differentiation, although not significant, between the wild plants on one hand and the cultivated plants on the other. Integrated studies focusing on morphological, genetic and ecological characterization of a larger number of wild populations would allow us to know the extent of the variability within the species.

Karyotype diversity in the genus Nysius Dallas, 1852 (Hemiptera, Heteroptera, Lygaeidae) is much greater than you might think.

We studied the karyotype and chromosomal distribution of 18S rDNA clustered in nucleolar organizer regions (NORs) in Nysiusgraminicola (Kolenati, 1845), belonging to the subfamily Orsillinae (Lygaeidae). It is shown that this species has a karyotype with 2n = 22(18+mm+XY), previously known in only one of 24 studied species of the genus Nysius Dallas, 1852, characterized by a similar karyotype, 2n = 14(12+mm+XY). In N.graminicola, 18S loci are located on sex chromosomes, which is a previously unknown trait for this genus. Our results in a compilation with previous data revealed dynamic evolution of rDNA distribution in Nysius. It is concluded that molecular chromosomal markers detected by FISH contribute to a better understanding of the structure and evolution of the taxonomically complex genus Nysius.

Human deleterious mutation rate implies high fitness variance, with declining mean fitness compensated by rarer beneficial mutations of larger effect.

Each new human has an expected Ud = 2 - 10 new deleterious mutations. This deluge of deleterious mutations cannot all be purged, and therefore accumulate in a declining fitness ratchet. Using a novel simulation framework designed to efficiently handle genome-wide linkage disequilibria across many segregating sites, we find that rarer, beneficial mutations of larger effect are sufficient to compensate fitness declines due to the fixation of many slightly deleterious mutations. Drift barrier theory posits a similar asymmetric pattern of fixations to explain ratcheting genome size and complexity, but in our theory, the cause is Ud > 1 rather than small population size. In our simulations, Ud ~2 - 10 generates high within-population variance in relative fitness; two individuals will typically differ in fitness by 15-40%. Ud ~2 - 10 also slows net adaptation by ~13%-39%. Surprisingly, fixation rates are more sensitive to changes in the beneficial than the deleterious mutation rate, e.g. a 10% increase in overall mutation rate leads to faster adaptation; this puts to rest dysgenic fears about increasing mutation rates due to rising paternal age.

Dramatic difference in rate of chromosome number evolution among sundew (Drosera L., Droseraceae) lineages.

Chromosome number change is a driver of speciation in eukaryotic organisms. Carnivorous sundews in the plant genus Drosera L. exhibit single chromosome number variation both among and within species, especially in the Australian Drosera subg. Ergaleium D.C., potentially linked to atypical centromeres that span much of the length of the chromosomes. We critically reviewed the literature on chromosome counts in Drosera, verified the taxonomy and quality of the original counts, and reconstructed dated phylogenies. We used the BiChrom model to test whether rates of single chromosome number increase and decrease, and chromosome number doubling differed between D. subg. Ergaleium and the other subgenera and between self-compatible and self-incompatible lineages. The best model for chromosome evolution among subgenera had equal rates of chromosome number doubling but higher rates of single chromosome number change in D. subg. Ergaleium than in the other subgenera. Contrary to expectation, self-incompatible lineages had a significantly higher rate of single chromosome loss than self-compatible lineages. We found no evidence for an association between differences in single chromosome number changes and diploidization after polyploidy or centromere type. This study presents an exemplar for critically examining published cytological data and rigorously testing factors that may impact the rates of chromosome number evolution.

"BIFloraExplorer": A Taxonomic, Genetic, and Ecological Data Resource for the Vascular Plants of Britain and Ireland.

The vascular flora of Britain and Ireland is a historically well-documented and clearly delimited study system that offers itself to large-scale analyses of ecology and species assemblages. However, such analyses require clean, curated, and taxonomically resolved data, which are often unavailable. In this chapter, we describe how to access and use a key data resource that combines a taxonomically stable species list with genetic data (genome size, chromosome counts, and DNA barcode information), ecological information (such as life-form, realized niche description, and geographic origin) and distribution records. The data resource enables and encourages the study of natural ecological and evolutionary patterns and processes within the vascular flora of Britain and Ireland.

CromoCat: Chromosome Database of the Vascular Flora of the Catalan Countries-25 years.

CromoCat is a plant chromosome database that evolved from previous versions, as a repository of karyological information on the vascular flora of the Catalan Countries. CromoCat is designed as an independent database, managed by a team based at the University of Barcelona directed by J. Simon, available from its own webpage ( http://www.cromo.cat/ ) and from the Flora section of the Catalan Biodiversity Database - BDBC ( http://biodiver.bio.ub.es ). CromoCat contains at present (mid 2022) more than 68,000 records of karyological data belonging to more than 5000 taxa. A synthesis of the development of CromoCat, its functional system, achievements, limitations, and adopted solutions, during 25 years (1996-2021) and updated 2022, as well as the application to biodiversity conservation and management are outlined.

DCDB: Chromosome Database of Tribe Delphinieae (Ranunculaceae): Structure, Exploitation, and Recent Development.

An updated (and now online) version of the former chromosome database of tribe Delphinieae (Ranunculaceae) is presented ( http://www.delphinieae.online ). This new version is the result of an accurate, exhaustive literature and Internet research, by adding chromosome counts and all related karyological information for the genera Aconitum L., Gymnaconitum (Stapf) Wei Wang & Z. D. Chen, Delphinium L. (including Staphisagria Spach), Consolida (DC.) S. F. Gray and Aconitella Spach, accumulated during the approximately last 25 years and that comprise worldwide published data from 1889 to 2021. The Delphinieae Chromosome Database (DCDB) (last updated 31.12.2021) contains a total number of 3435 reports belonging to 425 species (503 taxa), which represents 48.6% of the total species of the tribe (an increase of c. 213% and 32% compared with the 1097 and 2598 reports gathered in the 1999 and 2016 versions, respectively). This increase is due both to chromosome research progress and to improved information capture system. Moreover, recent taxonomic advances, synonymization, and new phylogenetic criteria have also been considered.The DCDB database provides the most complete currently available information on published chromosome numbers, ploidy-level estimates, and other karyological data of Delphinieae, and it is aimed to be useful for the building of cytotaxonomical databases and for specific research ongoing projects of systematics and evolution of Ranunculaceae. DCDB includes two levels of taxonomic resolution, published name (original and standardized form) and database accepted name (based on either Plants of the World - POWO or expert specialist criteria), as well as the geographic origin of each count (country, locality, geographic coordinates, elevation, or ecological information when reported in the original publication), associated karyological data if originally provided (studied material type, graphic information, chromosome measures and formulas, satellites, B chromosomes, other cytogenetic techniques used, etc.), voucher information and reference (with DOI and other links to access the original document). An effort to check the original sources and to search in grey literature allowed to indicate the counts that appear to be registered twice.

Chilean Plants Cytogenetic Database: An Online Resource for Embryophytes of the Southern Cone.

Chilean Plants Cytogenetic Database (CPCD) is a resource available online in electronic format, providing a cytogenetics catalog for continental and insular Chilean plants that are representative of the floras of the Southern Cone. In the last update carried out in 2021, we increased the cytogenetic data for 499 Chilean native species, and from here on we will include a new section with chromosome number data for 683 exotic species classified as invaders in Chile. Aspects on the coverage, features, and uses of the CPCD are presented here, including background information accumulated since its inception in 2010 to the present. With the new update, the database currently stores cytogenetic information for species belonging to the divisions Bryophyta, Pteridophyta, Pinophyta, and Magnoliophyta, thus contributing to the largest community resource on plant cytogenetics in the world.

Karyotype of Sabanejewiabulgarica (Drensky, 1928) (Teleostei, Cobitidae) from the Danube Delta, Romania.

The karyotype of the freshwater fish Sabanejewiabulgarica (Drensky, 1928), from the Danube Delta, was studied by conventional Giemsa staining and the C-banding technique. The diploid chromosome number was 2n = 50. The karyotype contained 2 pairs of metacentric (the first one was much larger than the second one), 6 pairs of submetacentric and 17 pairs of subtelocentric to acrocentric chromosomes. Pericentromeric blocks of heterochromatin were revealed in most of the chromosome pairs. The karyotype phenotype of S.bulgarica was the same as found for S.balcanica from Northern Carpathian Mountains.

Optimal protocol for in vitro polyploid induction of Cymbidium aloifolium (L.) Sw.

BACKGROUND: Cymbidium aloifolium is a popular ornamental flower in Thailand with both economic and medical values. Polyploid induction techniques are used to improve plant quality. This study identified polyploidy levels of C. aloifolium induction by colchicine. Protocorms of C. aloifolium were treated on solid New Dogashima Medium (NDM) with various concentrations of colchicine (0, 0.01, 0.02, 0.03, 0.04 and 0.05% w/v) for 2, 4 and 8 weeks. RESULTS: Colchicine effectively induced plant polyploidy. Tetraploid plants were found after treatment with 0.03% and 0.04% colchicine for 8 weeks, while at increased concentration and duration, survival, response and growth performance decreased. Tetraploid plants showed the lowest growth performance but highest size of stomatal and epidermal cells. Growth performance and leaf surface anatomy data were analyzed by Pearson's correlation and PCA. Results showed that stomatal and epidermal cell sizes had strongly negative correlations with other variables, while HCA revealed that stomatal and epidermal cell sizes of tetraploid plantlets were larger but stomatal and epidermal cell densities decreased when compared with the diploids. CONCLUSION: Colchicine at suitable concentrations and duration produced polyploid plants with alteration of morphological and anatomical traits. This study provides potential information to support orchid quality production as ornamental plants and a source of pharmaceutical raw materials.

Online Resources Useful for Plant Cytogenetics and Cytogenomics Research.

The advancements in research in the field of plant cytogenetics and genomics in recent decades have led to a significant increase in publications. To simplify access to the widely dispersed data, there has been a rise in the number of online databases, repositories, and analytical tools. This chapter presents a comprehensive overview of these resources, which can be beneficial to researchers in these areas. It includes, among others, databases on chromosome numbers, special chromosomes (such as B chromosomes or sex chromosomes), some of which are taxon-specific; genome sizes, cytogenetics; and online applications and tools for genomic analysis and visualization.

Ranunculusmaoxianensis (Ranunculaceae), a new species from northwestern Sichuan, China, with an emended description of R.chongzhouensis, the putative closest ally of the new species.

Ranunculusmaoxianensis (Ranunculaceae), a new species from Jiuding Shan in Maoxian county, northwestern Sichuan province, China, is here illustrated and described. The species is morphologically similar to R.chongzhouensis, a species also occurring in Sichuan, in having reniform leaves and puberulous receptacles, carpels and achenes, but differs by having leaves adaxially puberulous with shorter appressed hairs 0.16‒0.28 mm long (vs. longer appressed hairs 0.55‒0.85 mm long), larger flowers (1.8‒2 cm vs. 1.4‒1.6 cm in diameter), larger (8‒10 × 5.5‒6.5 mm vs. 6‒7 × 4.5‒5 mm) and widely obovate petals (vs. obovate), more numerous stamens (35‒55 vs. 12‒18), and subglobose gynoecium and aggregate fruit (vs. ellipsoid). The two species are also different in chromosome number and chromosome morphology. Ranunculuschongzhouensis has a karyotype of 2n = 2x = 16 = 10m + 6sm while R.maoxianensis has a karyotype of 2n = 4x = 32 = 16m + 16sm. An emended description of R.chongzhouensis is provided, and its geographical distribution is largely extended.

Chromosome-length genome assemblies and cytogenomic analyses of pangolins reveal remarkable chromosome counts and plasticity.

We report the first chromosome-length genome assemblies for three species in the mammalian order Pholidota: the white-bellied, Chinese, and Sunda pangolins. Surprisingly, we observe extraordinary karyotypic plasticity within this order and, in female white-bellied pangolins, the largest number of chromosomes reported in a Laurasiatherian mammal: 2n = 114. We perform the first karyotype analysis of an African pangolin and report a Y-autosome fusion in white-bellied pangolins, resulting in 2n = 113 for males. We employ a novel strategy to confirm the fusion and identify the autosome involved by finding the pseudoautosomal region (PAR) in the female genome assembly and analyzing the 3D contact frequency between PAR sequences and the rest of the genome in male and female white-bellied pangolins. Analyses of genetic variability show that white-bellied pangolins have intermediate levels of genome-wide heterozygosity relative to Chinese and Sunda pangolins, consistent with two moderate declines of historical effective population size. Our results reveal a remarkable feature of pangolin genome biology and highlight the need for further studies of these unique and endangered mammals.

The genome size, chromosome number and the seed adaption to long-distance dispersal of Ipomoea pes-caprae (L.).

Ipomoeapes-caprae (L.) (IPC) is a common species in tropical and subtropical coastal areas and one of the world's most widely distributed plants. It has attracted researchers for its outstanding biological, ecological and medicinal values. It has been reported that the genetic diversity of IPCs located on different continents is very low because of their frequent gene flow. During the long journey of evolution, every aspect of the plant morphologies has evolved to the best adaptivity to the environment, seeking their survival and progeny expansion. However, the fundamental genetic characteristics of IPC and how their seed adapted to the success of population expansion remain unknown. In this study, the fundamental genetic characteristics, including the genome size and the chromosome number of IPC, were investigated. The results showed that IPC's genome size is approximately 0.98-1.08 GB, and the chromosome number is 2n=30, providing the basic information for further genome analysis. In order to decipher the long-distance dispersal secret of this species, the fruit and seed developments, seed morphology, and seed germination were extensively investigated and described. The results showed an exquisite adaptive mechanism of IPC seeds to fulfil the population expansion via ocean currents. The large cavity inside the seeds and the dense tomenta on the surface provide the buoyancy force for the seeds to float on the seawater. The hard seed coats significantly obstructed the water absorption, thus preventing the seed from germination during the dispersal. Meanwhile, the fully developed embryos of IPC also have physiological dormancy. The physical and physiological characteristics of IPC seeds provide insight into the mechanism of their long-distance dispersal across the oceans. Moreover, based on morphological observation and semi-section microscopy, the development pattern of IPC glander trichomes was described, and their physiological functions were also discussed.

Cytogeography of Naturalized Solidago canadensis Populations in Europe.

Autopolyploidization has driven the successful invasion of Solidago canadensis in East Asia. However, it was believed that only diploid S. canadensis invaded Europe, whereas polyploids never did. Here, molecular identification, ploidy level, and morphological traits of ten S. canadensis populations collected in Europe were compared with previously identified S. canadensis populations from other continents and S. altissima populations. Furthermore, the ploidy-driven geographical differentiation pattern of S. canadensis in different continents was investigated. All ten European populations were identified as S. canadensis with five diploid and five hexaploid populations. Significant differences in morphological traits existed among diploids and polyploids (tetraploids and hexaploids), rather than between polyploids from different introduced ranges and between S. altissima and polyploidy S. canadensis. The invasive hexaploids and diploids had few differences in latitudinal distributions in Europe, which was similar to the native range but different from a distinct climate-niche differentiation in Asia. This may be attributed to the bigger difference in climate between Asia and Europe and North America. The morphological and molecular evidences proved the invasion of polyploid S. canadensis in Europe and suggest that S. altissima may be merged into a complex of S. canadensis species. Our study may be concluded that geographical and ecological niche differentiation of an invasive plant driven by ploidy depends on the degree of difference in the environmental factors between the introduced and native range, which provides new insight into the invasive mechanism.

Expanding the Chromosomal Evolution Understanding of Lygaeioid True Bugs (Lygaeoidea, Pentatomomorpha, Heteroptera) by Classical and Molecular Cytogenetic Analysis.

The Lygaeoidea comprise about 4660 species in 790 genera and 16 families. Using standard chromosome staining and FISH with 18S rDNA and telomeric (TTAGG)n probes, we studied male karyotypes and meiosis in 10 species of Lygaeoidea belonging to eight genera of the families Blissidae, Cymidae, Heterogastridae, Lygaeidae, and Rhyparochromidae. Chromosome numbers were shown to range from 12 to 28, with 2n = 14 being predominant. All species have an XY system and all but one have a pair of m-chromosomes. The exception is Spilostethus saxatilis (Lygaeidae: Lygaeinae); in another species of Lygaeinae, Thunbergia floridulus, m-chromosomes were present, which represents the first finding for this subfamily. All species have an inverted sequence of sex chromosome divisions ("post-reduction"). The 18S rDNA loci were observed on one or both sex chromosomes in Kleidocerys resedae and Th. floridulus, respectively (Lygaeidae), while on an autosomal bivalent in all other species. The rDNA loci tended to be close to the end of the chromosome. Using (TTAGG)n-FISH, we were able to show for the first time that the Lygaeoidea lack the canonical "insect" telomere motif (TTAGG)n. We speculate that this ancestral motif is absent from the entire infraorder Pentatomomorpha being replaced by some other telomere repeat motif sequences.

Differentiation between Bulinus truncatus and Bulinus hexaploidus by morphological characters, chromosomal study and compatibility with Schistosoma haematobium.

Schistosomiasis is a snail-born, neglected tropical disease (NTD) caused by blood flukes (trematode worms) of the genusSchistosoma. It is the second most socioeconomically devastating parasitic disease after malaria. Urogenital schistosomiasis is caused by Schistosoma haematobium which is transmitted by snail intermediate host of the genus Bulinus. This genus is a model system for the study of polyploidy in animals. This study aims to investigate ploidy levels existing among the Bulinus species and their compatibility with S. haematobium. The specimens were collected from two governorates in Egypt. Chromosomal preparation was made from gonad tissue (ovotestis). This study found two ploidy levels (tetraploid, n = 36 and hexaploid, n = 54) of B. truncatus/tropicus complex in Egypt. Tetraploid B. truncatus was found in El-Beheira governorate while-unexpectedly and for the first time in Egypt, the hexaploid population was found in Giza governorate. This identification focused on shell morphology, chromosomal count, and spermatozoa of each species. Afterward, all species were exposed to S. haematobium miracidia where B. hexaploidus snails were the only refractory species. The histopathological study showed early destruction and abnormal development of S. haematobium in B. hexaploidus tissues. In addition, the hematological investigation showed increasing in the total hemocyte count, the formation of vacuoles, several pseudopodia, and more dense granules in the hemocytes of infected B. hexaploidus snails. In conclusion, there were two types of snails one was refractory and the other was susceptible.

Karyotypic diversity: a neglected trait to explain angiosperm diversification?

Evolutionary changes in karyotype provide genetic support to organisms' differentiation and adaptation; however, the association between karyotype diversity and species diversification in flowering plants (angiosperms) remains to be fully elucidated. We sought evidence for this association within a phylogenetic framework using a dataset comprising > 413,000 worldwide chromosome counts of 66,000 angiosperms species. Karyotypic diversity (e.g., number of distinct chromosome numbers) explains species richness and diversification rates at both family and genus levels highlighting that chromosome evolution has probably played, at least, an important role in reinforcing speciation that was already initiated or completed by other geographical or ecological drivers. Thus, research programs investigating chromosome variation as a direct or indirect driver of diversification should be encouraged.