SAT Chromosomes Research Articles

Molecular Profile of the HepG2 Tumor Cell Line

Cell lines are widely used in scientific research due to their accessibility, stability, and functional similarity to the original cells. The HepG2 line, being the fourth most popular cell culture, is often used in toxicological and metabolic studies due to its partial retention of hepatocyte properties.In our study, the molecular portrait of the HepG2 cell culture was constructed for the first time. To build this portrait, we used previously obtained data for a single sample, including results of whole-genome sequencing (WGS), whole-genome bisulfite sequencing (WGBS), transcriptome (RNA-seq), translatome (Polysome-seq), and proteome (LC-MS/MS) profiling. For the assessment of HepG2 cell line heterogeneity, we analyzed whole-genome and transcriptome data published in the NCBI SRA database, as well as proteome research results available in the PRIDE resource.Our study showed that the HepG2 cell line generally demonstrates a high degree of stability at the genomic and transcriptomic levels; however, samples from China require closer attention when transferring the results of transcriptomic and proteomic experiments. The HepG2 genotype is characterized by stable chromosomal rearrangements, such as translocation between the short arms of chromosomes 1p and 21p, tetrasomy of chromosome 20, loss of the short arm of all SAT chromosomes, and the long arm of the Y chromosome. Despite the absence of 1216 protein-coding genes at the genomic level, 12,602 genes are expressed at the transcriptomic level, of which only 10,461 are detected at the translatome level, and only 1027 genes are identified at the proteome level, which is related to the limitations of mass spectrometry sensitivity. As a result of the omics data analysis, we presented a detailed molecular portrait of the HepG2 cell culture, illustrating the omics profile at various levels for each gene.

Karyotype diversity in cultivated and wild Indian rice through EMA-based chromosome analysis

India is known for its diverse cultivated and wild rice germplasm. In today's crop improvement programmes, wild relatives are much-needed genetic repository of valuable traits. Analysis of genetic diversity at the chromosomal level is one cost-effective tool to unlock foundational information related to genetics and plant breeding. Presently, enzymatic maceration and air-drying method (EMA) has been applied for the first time in six cultivated and nine wild Indian rice (diploid and tetraploid). EMA method following Giemsa staining has yielded large numbers of cytoplasm free metaphase plates with distinct chromosome morphology. Detailed analysis has revealed karyotype diversities in terms of total chromatin length (TCL), chromosome morphology and location of sat chromosomes within and between the studied species. Most of the cultivated rice has gained additional amount in TCL during the period of domestication in comparison to their progenitor Oryza nivara. Morphological clarity of the small chromosomes of rice was much required and has helped to identify individual chromosomes in the diverse karyotypes. Diversity in landmark SAT chromosomes is another important observation, not reported previously in Indian rice. Present study has shown that in most of the O. sativa members, the 10th pair contains SAT except one where 6th pair is satellited. On the other hand, diversity of SAT in diploid and tetraplod wild species has been recorded on 5th, 7th and 8th chromosome pairs and on 9th, 12th, 22nd and 23rd chromosome pairs, respectively. Karyomorphometric indices has helped to construct dendrogram to elucidate intraspecies and interspecies relationships. Untapped genetic diversity recorded in Indian rice through chromosomal analysis will be useful to the breeders and genome researchers.

Patterns of chromosomal variation in Mexican species of Aeschynomene (Fabaceae, Papilionoideae) and their evolutionary and taxonomic implications.

A cytogenetic analysis of sixteen taxa of the genus Aeschynomene Linnaeus, 1753, which includes species belonging to both subgenera Aeschynomene (Léonard, 1954) and Ochopodium (Vogel, 1838) J. Léonard, 1954, was performed. All studied species had the same chromosome number (2n = 20) but exhibited karyotype diversity originating in different combinations of metacentric, submetacentric and subtelocentric chromosomes, chromosome size and number of SAT chromosomes. The plasticity of the genomes included the observation in a taxon belonging to the subgenus Aeschynomene of an isolated spherical structure similar in appearance to the extra chromosomal circular DNA observed in other plant genera. By superimposing the karyotypes in a recent phylogenetic tree, a correspondence between morphology, phylogeny and cytogenetic characteristics of the taxa included in the subgenus Aeschynomene is observed. Unlike subgenus Aeschynomene, the species of Ochopodium exhibit notable karyotype heterogeneity. However the limited cytogenetic information recorded prevents us from supporting the proposal of their taxonomic separation and raise it to the genus category. It is shown that karyotype information is useful in the taxonomic delimitation of Aeschynomene and that the diversity in the diploid level preceded the hybridization/polyploidization demonstrated in the genus. The systematic implications of our results and their value can be extended to other Dalbergieae genera as knowledge about the chromosomal structure and its evolution increases.

Genomic characterisation of Arachis porphyrocalyx (Valls & C.E. Simpson, 2005) (Leguminosae): multiple origin of Arachis species with x = 9.

The genus Arachis Linnaeus, 1753 comprises four species with x = 9, three belong to the section Arachis: Arachis praecox (Krapov. W.C. Greg. & Valls, 1994), Arachis palustris (Krapov. W.C. Greg. & Valls, 1994) and Arachis decora (Krapov. W.C. Greg. & Valls, 1994) and only one belongs to the section Erectoides: Arachis porphyrocalyx (Valls & C.E. Simpson, 2005). Recently, the x = 9 species of section Arachis have been assigned to G genome, the latest described so far. The genomic relationship of Arachis porphyrocalyx with these species is controversial. In the present work, we carried out a karyotypic characterisation of Arachis porphyrocalyx to evaluate its genomic structure and analyse the origin of all x = 9 Arachis species. Arachis porphyrocalyx showed a karyotype formula of 14m+4st, one pair of A chromosomes, satellited chromosomes type 8, one pair of 45S rDNA sites in the SAT chromosomes, one pair of 5S rDNA sites and pericentromeric C-DAPI+ bands in all chromosomes. Karyotype structure indicates that Arachis porphyrocalyx does not share the same genome type with the other three x = 9 species and neither with the remaining Erectoides species. Taking into account the geographic distribution, morphological and cytogenetic features, the origin of species with x = 9 of the genus Arachis cannot be unique; instead, they originated at least twice in the evolutionary history of the genus.

Searching chromosomal landmarks in Indian lentils through EMA-based Giemsa staining method.

Lentil is one of the oldest protein-rich food crop with only one cultivated and six wild species. India is one important cultivator, producer and consumer of lentils and possesses a large number of germplasms. All species of lentil show 2n = 14 chromosomes. The primary objective of the present paper is to search chromosomal landmarks through enzymatic maceration and air drying (EMA)-based Giemsa staining method in five Indian lentil species not reported elsewhere at a time. Additionally, gametic chromosome analysis, tendril formation and seed morphology have been studied to ascertain interspecific relationships in lentils. Chromosome analysis in Lens culinaris, Lens orientalis and Lens odemensis revealed that they contain intercalary sat chromosome and similar karyotypic formula, while Lens nigricans and Lens lamottei showed presence of terminal sat chromosomes not reported earlier. This distinct morphological feature in L. nigricans and L. lamottei may be considered as chromosomal landmark. Meiotic analysis showed n = 7 bivalents in L. culinaris, L. nigricans and L. lamottei. No tendril formation was observed in L. culinaris, L. orientalis and L. odemensis while L. nigricans and L. lamottei developed very prominent tendrils. Based on chromosomal analysis, tendril formation and seed morphology, the five lentil species can be separated into two distinct groups. The outcome of this research may enrich conventional and biotechnological breeding programmes in lentil and may facilitate an easy and alternative method for identification of interspecific hybrids.

RDNA loci and heterochromatin positions support a distinct genome type for ‘x = 9 species’ of section Arachis (Arachis, Leguminosae)

Most species of the genus Arachis (Leguminosae; 80 spp.) are diploid with x = 10 and only four species have x = 9 chromosomes. Three of these x = 9 species belong to section Arachis and are morphologically and chromosomally similar. To study the homeology of the genomes of x = 9 species and their relation to other genomes in section Arachis, we applied fluorescence in situ hybridization (FISH) of 18S–26S and 5S rDNA and 4′,6-diamidino-2-phenylindole (DAPI) banding. FISH revealed for these three species one pair of 5S rDNA sites interstitially within the short arm of the metacentric pair 6 and one pair of 18S–26S rDNA sites in the proximal region of the long arm of the SAT chromosomes. Conspicuous DAPI+ bands were detected pericentromerically in all nine chromosome pairs of A. decora and A. praecox and in all but one pair of A. palustris. Our results suggest that all three species with x = 9 of section Arachis share the same genome type and are different from the other genome types A, B, D, F, and K described for this section. Apparently, the x = 9 species of section Arachis form a monophyletic group characterized by a genome type, that we propose to call G genome.

Karyotype analysis in Chaerophyllum cicutaria Vill. with special emphasis on satellited chromosomes

Karyological studies were carried out on plants of <em>Chaerophyllum cicutaria (Umbelliferae)</em>, which came from both lowland and montane natural populations. The chromosome number in all the examined plants was 2n = 22 and their karyotypes, though similar in general, showed some minute but distinct differences. There was` a single pair of SAT chromosomes in the chromosome complement. They had compound satellites divided into two or three segments. Seven morphological types of SAT chromosomes differing in number and size of satellite segments were distinguished. With respect to SAT chromosome morphology, the species showed both intra- and interpopulational karyological variation.

Methodology Molecular cytogenetic characterization of the Aegilops biuncialis karyotype

Aegilops biuncialis can be hybridized with wheat (Triticum spp) and has been used for wheat breeding and genetic studies. The A. biuncialis karyotype (U(b) U(b) M(b) M(b)) was investigated based on three A. biuncialis accessions grown in China. Two pairs of SAT chromosomes were identified as 1U(b) and 5U(b), with a karyotype formula of 2n = 4x = 28 = 14m + 10sm + 4st. Fluorescence in situ hybridization (FISH) and C-banding approaches were used to analyze the A. biuncialis accession chromosomes at the mitotic stage. Based on the C-banding and FISH patterns, all U(b) and M(b) chromosomes could be discriminated simultaneously; the three A. biuncialis accessions exhibited similar patterns, suggesting a common origin. The U(b) genome from A. biuncialis resembled the U genome in the diploid species A. umbellulata, and it may be related to the tetraploid species containing the U genome. The M(b) genome had some differences compared to the M genome in the diploid species A. comosa, and it may be related to the tetraploid species possessing the M genome. A generalized ideogram was proposed for the A. biuncialis genome, which could be useful for standardized and accurate identification of the A. biuncialis karyotype and chromosomes.

English

  Karyotype and morphology of mitotic chromosomes in six populations of the medicinal plant Papaver rhoeas collected from various geographical locations of the northwest of Iran were studied. Chromosome characteristics were measured from 10 complete metaphase cells using micromeasure software. The results showed that P. rhoeas is a diploid species with 2n=2x=14 chromosomes. The karyotype consisted of seven pairs of submetacentric chromosomes with one pairs of SAT chromosome (chromosome 2) having a secondary constriction at the end of its short arm. Karyological characteristics of all the materials studied were similar to each other; however, there were some variations on chromosome arm ratios and relative lengths among the different populations. All of the populations are placed on 4A class of Stebbin’s asymmetry categories.   Key words: Biodiversity, chromosome analysis, medicinal plants, Papaveraceae.

Characterization of chromosome complement in Filifolium sibilicum (L.) Kitamura by aceto-orcein, CMA, DAPI and FISH 5S and 45S rDNA

The chromosome characteristics of Filifolium sibilicum (2n=18) were studied regarding the karyotype by aceto- orcein, locations of the G-C and A-T rich regions by CMA and DAPI, and FISH. The karyotypes of six representative individuals in three localities such as two sites in Inner Mongolia Autonomous Region, The People's Republic of China and one site in Buryat Republic in Russian Federation consisted commonly of 12 median-centromeric, four satellited median-centromeric and four submedian-centromeric chromosomes. CMA-stained the whole chromosomes, but four brighter bands were on terminal positions of four chromosomes and were convenient with the four sat chromosomes. DAPI-stained the whole metaphase chromosomes. Applying FISH using the biotin labeled probe of 5S rDNA and digoxigenin labeled pTa71 probe of 45S rDNA on the mitotic chromosomes showed four yellow colored signals of the 5S rDNA and four red signals that were terminally co-localized, which were obtained after hybridization of the probes with two submedian and two subterminal metaphase chromosomes.

Cytological investigations in poly-gamo-dioecious tree Simarouba glauca DC

In angiosperms sexual dimorphism is proved to be an evolutionary advancement and plays a major role in crop improvement in general and in tree species in particular. Identification of sex in absence of morphological markers is a difficult task in such plants. Sex determination in all dioecious plants does not follow a common mechanism. In present investigation an attempt is made to understand the mechanism of sex determination in poly-gamo-dioecious tree species Simarouba glauca DC., an important oil yielding and medicinal plant. Scoring of morphological characters in male and female S. glauca reveals that both are morphologically identical with 2n = 30 chromosomes and exhibit symmetric karyotype and with homomorphic median chromosomes with one pair of SAT chromosomes, but female plant possess chromosomes which are longer than male counterpart and the largest chromosome is more than two fold longer than the smallest.

Giemsa C-banding and silver-staining for cytological studies in Pisum

Technical hints are given for Giemsa C-banding of the Pisum chromosomes and for silver-staining of NORs and nucleoli. C-band positive heterochromatin appears as pairs of centromeric dots on each of the seven chromosomes and as heavily stained C-bands at the secondary constrictions in the long arms of chromosomes 4 and 7. In the latter arm, there is also an intercalary proximally situated C-band. The centromeric dots are attached to chromosomal spindle fibres, which supports the supposition that they are kinetochores. The C-blocks of the SAT regions are also detectable at metaphase I of meiosis and hence facilitate the interpretation of configurations in structural hybrids involving the SAT chromosomes. In mitotic interphase nuclei, the SAT blocks appear as four chromocentres, and in the giant nuclei of the suspensor, as four endochromocentres. Ag-NORs coincide with the C-bands at the SAT regions. Moreover, the centromeric dots are stained by silver nitrate. In Pisum, nucleoli may be formed from the centromeric regions of the chromosomes. At late mitotic prophase (diminishing stage of nucleolar development), the nucleoli sometimes appear as paired heavily silver-stained bodies budding out from the chromosomes. At meiotic prophase, darkly stained intranucleolar bodies occur in slides prepared according to a suitable silver-staining technique.

Genetic variations in Lycoris radiata var. radiata in Japan

The genetic variations of Lycoris radiata var. radiata, a completely sterile triploid from Japan, were examined by comparing the nucleotide sequences of genomic DNA regions in 11 triploid strains sampled from Japan and four triploid strains sampled from China, and in two diploid strains of Lycoris radiata var. pumila, which is endemic to China and fertile. For this purpose, two genes were analyzed, the lectin gene in the nuclear genome and the maturase gene in the chloroplast genome. A clear genetic constancy was observed in their DNA nucleotide sequences. For both genes, completely identical nucleotide sequences were detected in the 11 Japanese and four Chinese triploid strains and also between the two Chinese diploid strains. However, some genetic variations were observed between the Japanese and Chinese triploid strains, and between the triploid and diploid strains. These results are consistent with the findings obtained from previous chromosome karyotype analyses and allozyme analyses. In addition, in our preliminary FISH analysis of the physical mapping of the rRNA gene family, the 18S-5.8S-26S rRNA and 5S rRNA loci were localized on six and four chromosomes, respectively. Regarding the 18S-5.8S-26S rRNA loci, two were associated with two SAT chromosomes. The remaining four were distinguished by having no secondary constriction. Localization of 5S rRNA loci to chromosome spreads revealed three sites on the proximal part of the long arm of three acrocentric chromosomes and one site on the distal part of the long arm of the SAT chromosome; the latter site was juxtaposed to the 18S-5.8S-26S rRNA loci. These findings indicate that L. radiata var. radiata is not a typical autotriploid. The present paper discusses the possible origin of L. radiata var. radiata from a diploid variety of L. radiata var. pumila, based on the molecular cytogenetic analysis and DNA sequence analysis.

Further Cytogenetic Information on Arachis stenosperma (Leguminosae)

Arachis stenosperma is a wild relative of the groundnut, with a peculiar disjunct distribution in Central Brazil and along the Atlantic coast. Arachis species show one pair of satellited chromosomes (SAT) and some species have a distinct, smaller pair (A pair). The SAT chromosomes are classified according to 10 types. Previous literature information on A. stenosperma documents the presence of SAT type 3 only in the coastal populations, while type 5 was restricted to accessions from Central Brazil. This work sampled a broader area of geographic distribution, represented by an increased number of accessions, and provides further information on karyotypic characteristics. All 23 accessions analyzed present 2n=20. SAT type 5 was found in 10 accessions, irrespective to their area of occurrence. So, type 5 occurs also in the Atlantic coast. Type 3, so far exclusive to the Litoral, is not the most frequent type in the area. With the present data, the potential cytogenetic distinction between coastal and continental populations has vanished. The formula 18m+2sm clearly predominates, both in the Litoral and in Central Brazilian populations. Also irrespective to the area of origin, both idiogram positions A9/SAT10 and SAT9/A10 were identified. As the SAT of type 3 is considered more primitive than type 5, and the coastal area of distribution of A. stenosperma is secondary, it's future detection in continental populations is expected. In the meantime, a unique cytogenetic feature, the presence of SAT type 3 persists as an exclusive attribute of the populations of the secondary area of occurrence.

Karyomorphological Analysis and Phylogenetic Relationship of Gossypium L Species

Karyomorphological analysis of seven Gossypium species belonging to ‘A’ (G. arboreum, G. herbaceum), ‘D’ (G. aridum, G. armourianum, G. davidsonii), ‘AD’ (G. hirsutum, G. barbadense) genome was carried out. All the species invariably shows the basic chromosome number as x=13. The chromosome size ranged from 1.1 to 4.7 μm. G. aridum had the smaller mean chromosome length (1.15 μm) while G. barbadense had the larger chromosome (4.7 μm). Karyotypes were of symmetrical type possessing long and short chromosomes in equal proportions. The satellite chromosomes were located in the long arm of one or two metacentric pair. The species varied with regards to number of SAT chromosomes and chromosome carrying secondary constrictions. Cluster analysis was done to group the species. It shows that the cotton species studied falls in to three distinct clusters. Results also revealed that the popular, cultivated American cotton G. hirsutum, and the Egyptian cotton G. barbadense might have originated from the crosses between the Asiatic cotton G. arboreum, G. herbaceum (‘A’ genome) and the American wild cotton G. aridum, G. armourianum, G. davidsonii (‘D’ genome). The present finding clearly indicates the genomic differences within the diploid species and between the diploid–tetraploid species of cotton can be utilised in hybridization programmes. Crossing of the species placed in distant clusters are suggested.

The Giemsa C-banded Karyotype of Crithopsis Delileana (Poaceae; Triticeae)

Three populations of Crithopsis delileunu had similar karyotypes. They included 14 large chromosomes; five pairs of metacentrics, one pair of submetacentrics, and one pair of metacentric SAT-chromosomes with rather small satellites. The karyotypes of two populations were investigated in detail through application of Giemsa C-banding, Giemsa N-banding and AgN0,-staining to meta- and interphases. The C-banding patterns included a few small to very small, mainly centromeric or telomeric bands. The chromosomes of the two populations were differentiated by banding pattern polymorphism. Banding patterns identified homologous and discriminated among non-homologous chromosomes within the same population. The scarcity of diagnostic bands prevented identification of homologous chromosomes between populations beyond the level obtained from morphology, i.e., of submetdcentrics and SAT chromosomes. N-banding produced no or few weak bands. Silver nitrate staining produced two NORs and two nucleoli corresponding to the number of SAT-chromosomes. The data give some support to a hypothesis of a closer relationship between the genera Critlzopsis and Tueniutherum, than between either of these and the genera Psuthyrostuchys and Hordeum.

Physical mapping of 18S-5.8S-26S and 5S ribosomal RNA gene families in three important vetches (Vicia species) and their allied taxa constituting three species complexes

The most-important vetch species, Vicia narbonensis (narbon vetch, section Faba), Vicia villosa (hairy vetch, section Cracca) and Vicia sativa (common vetch, section Vicia) and their close relatives (often difficult to circumscribe into distinct taxa) constitute respectively, Narbonensis, Villosa and Sativa species complexes in the genus Vicia. The distribution of the 18S-5.8S-26S (18S-26S) and 5S ribosomal RNA (rRNA) gene families on the chromosomes of 19 (2n=2x=10,12,14) of the 24 species and subspecies belonging to the three species complexes, and Vicia bithynica (2n=12, section Faba) and Vicia hybrida (2n=12, section Hypechusa) was studied by fluorescence in situ hybridization (FISH) with pTa 71 (18S-26S rDNA) and pTa 794 (5S rDNA) DNA clones. Computer – aided chromosome analysis was performed on the basis of chromosome length, the arm-length ratio and the position of the hybridization signals. The positions of the four (2+2) signals of the two rRNA gene families were similar between each of the three, as well as two subspecies of V. narbonensis and Vicia johannis, respectively. Two major 18S-26S rDNA loci were found in the nucleolus organiser regions (NORs) of each of the species except V. hybrida, where it was present in two out of four SAT chromosomes. In addition to major NORs, two minor loci have been physically mapped at the centromeric regions of chromosomes of group 1 in Vicia amphicarpa, Vicia macrocarpa and V. sativa, and two NORs of group 5 in V. hybrida, and on the long arms of group 4 in V. bithynica. Two or four 5S rDNA loci, observed in the short arms of groups 2–4 and 5, and 18S-26S rDNA loci were located in different chromosomes of all the species within the Narbonensis and Villosa species complexes, and Vicia angustifolia of the Sativa species complex. In the remaining six species of the Sativa species complex, and V. bithynica and V. hybrida, the two or four 5S rDNA sites were present in chromosomes which harbor 18S-26S rRNA genes. The tandemly repeated 5S rDNA sites, located at the proximal part of the long arm of groups 3–5, were diagnostic for V. angustifolia, Vicia cordata, Vicia incisa, V. macrocarpa, Vicia nigra and V. sativa of the Sativa species complex. In V. amphicarpa of the same complex, the tandem repeats were located at the distal part of the long arms of group 3. Variability in the number, size and location of two ribosomal DNA probes could generally distinguish species within the Narbonensis and Sativa species complex, V. bithynica and V. hybrida. With respect to the four species of the Villosa species complex the karyotypes could not be identified individually on the basis of the distribution of two ribosomal gene families in three out of seven pairs of chromosomes.

Chromosome studies in wild Arachis(Leguminosae)

Abstract New chromosome numbers of seven peanut species, A. cryptopotamica Krapov. and W.C. Gregory and A. douradiana Krapov. and W.C. Gregory (Sect.Erectoides), A. subcoriacea Krapov. and W.C. Gregory and chiquitana Krapov.,W.C. Gregory and C.A. Simpson (Sect. Procumbentes), A. cruziana Krapov., W.C.Gregory and C.A. Simpson, A. Herzogii Krapov., W.C. Gregory&C.A. Simpson and A. Simpsonii Krapov. and W.C. Gregory (Sect. Arachis) have been determined,all of them have 2n=20. SAT chromosomes were analysed for all species and a new type of satellited chromosome was described for the genus, which was named 3B for its close resemblance to the first described 3 type. “A” chromosomes were only found in A. Herzogii, A. Simpsonii and A. chiquitana from all the studied species. The last one belong to the section Procumbentes, however, the type of satellited chromosome and the presence of “A” chromosomes in its karyotype suggest that it should be moved from section Procumbentes. The presence of A chromosomes prov...

Discrimination of the closely related A and D genomes of the hexaploid oat Avena sativa L.

A satellite DNA sequence, As120a, specific to the A-genome chromosomes in the hexaploid oat, Avena sativa L., was isolated by subcloning a fragment with internal tandem repeats from a plasmid, pAs120, that had been obtained from an Avena strigosa (As genome) genomic library. Southern and in situ hybridization showed that sequences with homology to sequences within pAs120 were dispersed throughout the genome of diploid (A and C genomes), tetraploid (AC genomes), and hexaploid (ACD genomes) Avena species. In contrast, sequences homologous to As120a were found in two A-genome species (A. strigosa and Avena longiglumis) and in the hexaploid A. sativa whereas this sequence was little amplified in the tetraploid Avena murphyi and was absent in the remaining A- and C-genome diploid species. In situ hybridization of pAs120a to hexaploid oat species revealed the distribution of elements of the As120a repeated family over both arms of 14 of 42 chromosomes of this species. By using double in situ hybridization with pAs120a and a C genome-specific probe, three sets of 14 chromosomes were revealed corresponding to the A, C, and D genomes of the hexaploid species. Simultaneous in situ hybridizations with pAs120a and ribosomal probes were used to assign the SAT chromosomes of hexaploid species to their correct genomes. This work reports a sequence able to distinguish between the closely related A and D genomes of hexaploid oats. This sequence offers new opportunities to analyze the relationships of Avena species and to explore the possible evolution of various polyploid oat species.

Comparison of the Giemsa C‐banded karyotypes of Hystrix coreana and H. patula (Poaceae, Triticeae)

The karyotypes of Hystrix coreana from eastern USSR and H. patula from USA were investigated by Giemsa C‐banding. Both species are outbreeders and have 2n = 4x = 28. The karyotype of two plants of H. coreana has 10 metacentric, 6 submetacentric, 8 heterobrachial and 4 SAT chromosomes; two plants differed by having 12 metacentric, 4 submetacentric, 8 heterobrachial and 4 SAT‐chromosomes, and 10 metacentric, 4 submetacentric, 9 heterobrachial and 5 SAT‐chromosomes, respectively. The C‐banding pattern had no or few inconspicuous intercalary bands, but conspicuous telomeric C‐bands in one or both arms giving a high content of heterochromatin (16.3–18.2%). The chromosome complement of one plant of H. patula had 8 metacentric, 6 submetacentric, 8 heterobrachial and 6 SAT‐chromosomes. The C‐banding pattern had between 1 and 4 intercalary or centromeric bands and conspicuous telomeric bands on one or both arms giving a high content of constitutive heterochromatin (16.4%).