Comparative Karyotype Analysis Research Articles

Comparative karyotype analysis among six species of Ipomoea based on two newly identified repetitive sequences.

Sweet potato is one of the most important crops worldwide; however, basic research in this crop is limited. In this study, we aimed to construct a detailed karyotype of six species of Ipomoea (hexaploid Ipomoea batatas and five related species, namely, one tetraploid, I. tabascana and four diploids, I. splendor-sylvae, I. trifida, I. tenuissima, and I. × leucantha) and understand the relationship among these species. Two satellite repeats (viz., Itf_1 and Itf_2) were identified from the diploid I. trifida genome sequence using RepeatExplorer on Galaxy. Together with the ribosomal DNA (rDNA), although without distinguishable chromosomes, a detailed karyotype was constructed for the six species. Our results showed a similar karyotype between I. tenuissima and I. × leucantha, indicating their close relationship. The signal distribution pattern of Itf_1, 45S rDNA combination, detected only in I. trifida, I. tabascana, and I. batatas, implied their close relationships. The chromosomes carrying 5S rDNA could be conserved among the six species as they always carried the Itf_2 signals, which generated a similar signal distribution pattern. The results enabled a detailed comparative cytogenetic analysis, providing valuable information to understand the relationship among these species and help assemble the genome sequence of the six species of Ipomoea.

Characterization of aneuploidy in interspecific hybrid between Urochloa ruziziensis (R. Germ. & Evrard) Crins and Urochloa decumbens (Stapf) R. D. Webster.

The aim of the study was to characterize the type of aneuploidy present in the hybrid Urochloa ruziziensis×Urochloa decumbens and to confirm the origin of the additional chromosomes through comparative analysis of the hybrid and parental karyotypes. C andCMA bandingtechniques were used for chromosome differentiation. The parental genotypes showed 36 chromosomes. The hybrid presented plants with 36 + 2 chromosomes and plants with 36 + 1 chromosomes. Urochloa ruziziensis (4x) presented four chromosomes with CMA and C bands co-located in the terminal position. In U. decumbens, four chromosomes presented terminal CMA bands, eight chromosomes were distinguished by Cbanding with pericentromeric and terminal bands, one chromosome with terminal band at both ends and one chromosome presented one Cterminal band. For the hybrid, CMA bands were found on five chromosomes and C bands on seven chromosomes, all in terminal position. Aneuploidy was identified in pairs 3' and 4' in the hybrid plants with 36 + 2 chromosomes, characterizing it as double trisomy. The karyotype of hybrid plants with 36 + 1 chromosomes indicated elimination of the additional chromosome identified in pair 4' and maintenance of trisomy on pair 3'. The comparative analysis of karyotypes indicates that the additional chromosomes that characterize the trisomy were inherited from U. ruziziensis (artificial tetraploid).

Evolution of trans-Andean endemic fishes of the genus Cheirodon (Teleostei: Characidae) are associated with chromosomal rearrangements

BackgroundAmong Neotropical fishes, the family Characidae is highly diverse and speciose and its taxonomy is not completely resolved. In Chile, the family is represented by five species, all within the genus Cheirodon, of which C. pisciculus, C. galusdae, C. kiliani, and C. australe are endemic, while C. interruptus is introduced. We compared chromosomal markers in order to appreciate the taxonomy and evolution of these trans-Andean fishes.ResultsThe specimens were photographed in stereomicroscope to observe the ventral protrusive teeth and cusps for morphological analysis and species identification. All of the species analysed had equally diploid chromosome number 2n = 50, with karyotypes dominated by high number of acrocentric chromosomes as compared to those of other members of Cheirodontinae. The distribution of heterochromatin was inconspicuous and was similar in all the species. The number of active NORs (nucleolus organizer regions) was polymorphic, with the greater number of them in C. kiliani and C. galusdae. The location of 5S and 18S rDNA ranged in number and position, showing two sites in different chromosomes. The fluorescent in situ hybridization with telomeric probe did not reveal interstitial sites in all analysed species.ConclusionsThe comparative analysis of karyotypes and morphological markers revealed a biogeographic pattern of distribution, with the species that occur in the southern region forming one group and those in central and northern Chile forming another.

Flow cytometry and cytogenetic tools in eucalypts: genome size variation × karyotype stability

The eucalypts comprise a group of woody plants used in commercial forest plantations owing to their high growth rates, adaptability to various ecological conditions and multiple applications. Despite the enormous amount of molecular data available for eucalypts, a basic understanding of the nature of its genome still requires information regarding the DNA amount in the genus. In this work, we estimated the genome size and base composition of 25 eucalypt species. With a comparative karyotype approach, we aimed to identify possible chromosomal alterations correlated with the genome size variation. Classical cytogenetic and genomic in situ hybridization experiments were conducted for this purpose. The studied species showed genome size ranging from 2C = 0.91 (Corymbia intermedia) to 2C = 1.37 pg (Eucalyptus paniculata) and AT/CG ratios varying from AT = 61.3 (Eucalyptus urophylla) to AT = 62.85% (C. intermedia). Comparative karyotype analysis revealed no remarkable differences in chromosome number (2n = 22) or morphology among eucalypt species despite considerable differences in nuclear DNA content. The genome in situ hybridization method did not distinguish non-homologous chromosomal regions of Eucalyptus baileyana and Corymbia citriodora, despite the difference of 0.45 pg between their genome sizes. The results found in the present work corroborate the consideration of small and dispersed DNA changes as the main cause of genome size variation in eucalypts.

Chromosome banding in <i>Picea</i> IV. Comparative karyotype analysis of fluorescent band patterns in 25 taxa

Chromosome banding in <i>Picea</i> IV. Comparative karyotype analysis of fluorescent band patterns in 25 taxa

Karyomorphological Analysis on Several Diploid Populations of Achillea biebersteinii Afan. (Asteraceae) from Iran

Comparative karyotype analysis of related species and populations has been used to describe patterns of chromosomal evolution within a group. In order to investigate cytogenetic variation in Achillea biebresteinii, root meristem zone of nine populations were removed and prepared using squash method. Image analysis system and Micro-measure software were implanted to karyotype providing cytogenetic parameter measurements. Although all the populations have the diploid chromosome number (2n = 18) and the haploid number (x = 9), but they could be differentiated by their karyotype formula and quantitative parameters of the karyotypes. Phenetic distance and principal component analysis showed that they could be classified in four clusters (groups). The mean chromosome length ranged from 3.82 (±0.48) to 7.77 (±0.12) µm. The chromosome types were detected as mostly metacentric (m) and submetacentric (sm), showing the karyotype formula of 18m (two populations), 16m + 2sm (five populations), 14m + 4sm (one population) and 2M + 14m + 2sm (one population). The karyotypes of the populations are almost similar. According to Stebbins’, the populations are classified to symmetric classes of 1A and 2A.

Chromosomes of Cichlasoma istlanum (Perciformes: Cichlidae) and karyotype comparison of two presumed subspecies

Cichlasoma istlanum (Jordan & Snyder, 1900) es un cíclido dulceacuícola que se encuentra en la provincia del Río Balsas en la Cuenca del Pacífico mexicano. De Buen (1946), basado en caracteres merísticos de la especie, propuso la división en dos subespecies: C. isrlana iSllana, procedente del Río Ixtla, en el estado de Morelos, y C. istlana fusca, del Río Huámito, Michoacán. En este trabajo se estableció el cariotipo de la especie por medio de procedimientos citogenéticos convencionales y de bandeo G, y se realizó un análisis comparativo de los cariotipos provenientes de las muestras de las dos poblaciones previamente propuestas como subespecies. Se recolectaron diez hembras en el Río Amacuzac, en el estado de Morelos, y nueve especímenes en el Río Huámito: dos hembras y siete machos. Mediante la cuenta de 264 campos mitóticos de la primera muestra y 203 de la segunda, se pudo establecer un número modal de 2n=48 en cada una, moda que se consideró correspondía al número diploide de la especie. El análisis cariotípico se basó en diez cariogramas preparados de la población de Morelos y de ocho de la de Michoacán, que incluyó tres provenientes de hembras y cinco de machos. La fórmula cromosómica encontrada fue de 8sm+40stt. El patrón de bandas G de ambas poblaciones fue similar y las comparaciones estadísticas de las longitudes promedio de los pares cromosómicos no mostraron diferencias significativas concluyentes entre ambas poblaciones. La existencia de un cariotipo prácticamente idéntico concuerda con la falta de diversificación subespecífica entre las poblaciones estudiadas. Los análisis morfométricos realizados por otros autores que encontraron sobreposición en los caracteres que fueron propuestos como distintivos de las dos subespecies, concuerdan con los resultados del presente estudio en que no se detectó divergencia suficiente para fundamentar la subdivisión de C. istlallum. La falta de divergencia poblacional encontrada puede deberse a un aislamiento geográfico disminuído por la existencia de flujo genético entre poblaciones contiguas a lo largo de su distribución en las diferentes regiones del Río Balsas, por un lapso de divergencia evolutiva relativamente corto a partir de su distribución en estas regiones y/o, con menor probabilidad, por un reemplazo de una población por la otra. La estabilidad carotípica encontrada pueda ser debida también a características, aun por identificarse y definirse, inherentes a la organización del genoma en este género

Karyotype characterization of the endemic piscine leech from Lake Baikal with vindication of Baicalobdella cottidarum Dogiel, 1957 (Piscicolidae, Hirudinea)

In this paper, we present for the first time data on karyotype analysis of leeches of the genus Baicalobdella (Piscicolidae) parasitizing Lake Baikal endemic cottoid fishes. Both mitotic and meiotic chromosomes are described. Leech testisacs were processed by a ?shaking-blotting? technique, and chromosomal preparations were stained with water-based fuchsine. Diploid and haploid chromosome sets demonstrated 2n=34 and n=17, respectively, with maximal chromosome length of 1.5-3.0 ?m. Comparative karyotype analysis of two ecological forms of Baicalobdella leeches revealed differences in chromosome numbers and its morphology. Previously studied Baicalobdella torquata (Grube, 1871) parasitizing Baikal amphipods had smaller diploid and haploid sets (2n=32, n=16). In addition to numerical superiority, differing patterns of chromosome size gradation and presence of satellite elements were found in the karyotype of piscine Baicalobdella leeches. This confirms the systematic position of the Baikal cottoid leech parasite as a separate species, validating the original name Baicalobdella cottidarum sensu Dogiel, 1957.

Comparative Analysis of Karyotypes of Two Cryptic Species of Pelobatid Frogs (Amphibia, Anura) of Ukraine

Abstract The paper first describes in detail the karyotype of Pelobates vespertinus (Pallas, 1771) in comparison with the karyotype of Pelobates fuscus (Laurenti, 1768). Comparative morphological analysis of chromosomes has shown that these two cryptic species have a symmetrical karyotype consisting of two-armed chromosomes. It has been established that their chromosome sets consist of 7 pairs of large chromosomes and 6 pairs of small ones. The species diff er by the position of the centromere in the chromosomes of the 10th and 11th pairs. The 10th pair of P. fuscus is metacentrics, the 11th pair is submetacentric; the 10th pair of P. vespertinus is submetacentric, and the 11th one is metacentrics. Secondary constrictions are on the short arms of the 7th chromosome pair. The chromosomal formula for both species is 4 meta-(m) + 7 submeta-(sm) + 2 subtelocentrics (st), 2n = 26, N.F. = 52. Absolute length of all the chromosomes in the karyotype of P. fuscus is somewhat larger than that one in the karyotype of P. vespertinus. The parameters of relative length are equivalent on average, but they diff er in individual chromosomes. On the background of established chromosomal differences between the cryptic species, reliable diagnostic features have not been identified.

Chromosome analysis in <I>Cupressus sempervirens</I> L., Cupressaceae <I>sensu stricto</I>

Cupressus sempervirens L. had the chromosome number of 2n=22 and its karyotype was composed of 22 metaand submeta-centric chromosomes with gradual variation in their lengths. In the chromosome complement six chromosomes had a secondary constriction at proximally interstitial region of the short arm and had CMA-bands on same positions of all secondary constrictions and neighbor regions. After silver staining six Ag-NORs appeared on nucleoli and chromosome at telophase, and at metaphase Ag-NORs appeared at the secondary constrictions of a few chromosomes. These results indicate all CMA-banded secondary constrictions have nucleolar organizing function. DAPI-bands appeared at interstitial and proximal regions of some chromosomes. A combination of chromosome morphology and fluorescent band patterns of the CMAand DAPI-stainings can identify all pairs of homologous chromosomes. Advantage of the fluorescent bandings for comparative karyotype analysis in Cupressus is discussed.

Chromosomal Characterization of the Three Subgenomes in the Polyploids of Hordeum murinum L.: New Insight into the Evolution of This Complex

Hordeum murinum L. is a species complex composed of related taxa, including the subspecies glaucum, murinum and leporinum. However, the phylogenetic relationships between the different taxa and their cytotypes, and the origin of the polyploid forms, remain points of controversy. The present work reports a comparative karyotype analysis of seven accessions of the H. murinum complex representing all subspecies and cytotypes. The karyotypes were determined by examining the distribution of the repetitive Triticeae DNA sequences pTa71, pTa794, pSc119.2, pAs1 and pHch950, the simple sequence repeats (SSRs) (AG)10, (AAC)5, (AAG)5, (ACT)5, (ATC)5, and (CCCTAAA)3 via in situ hybridization. The chromosomes of the three subgenomes involved in the polyploids were identified. All tetraploids of all subspecies shared the same two subgenomes (thus suggesting them to in fact belong to the same taxon), the result of hybridization between two diploid ancestors. One of the subgenomes present in all tetraploids of all subspecies was found to be very similar (though not identical) to the chromosome complement of the diploid glaucum. The hexaploid form of leporinum came about through a cross between a tetraploid and a third diploid form. Exclusively bivalent associations among homologous chromosomes were observed when analyzing pollen mother cells of tetraploid taxa. In conclusion, the present results identify all the individual chromosomes within the H. murinum complex, reveal its genome structure and phylogeny, and explain the appearance of the different cytotypes. Three cryptic species are proposed according to ploidy level that may deserve full taxonomic recognition.

Correlation of mutagenesis level with expression of reparative enzyme O6-methylguanine DNA methyltransferase during establishment of cell lines in vitro

Long-term cultivation of cell lines inevitably leads to genetic and epigenetic changes. Aim. A comparative analysis of karyotype and level of the expression of reparative enzyme O 6 -methylguanine-DNA-methyltransferase (MGMT) at different stages of establishment and stabilization of human cell line 4BL and cell line of mouse germ cells G1. Methods. The set of methods was used to research the dynamics of karyotypes changes: the differential staining of chromosomes, FISH-method and comparative genomic hybridization. The level of MGMT expression was analyzed by PCR reaction and Western blot analysis. Results. General trends of establishment of mouse and human cell lines were revealed: at the first stage, which is characterized by increased structural instability of the genome, an increase in the MGMT expression was revealed while at the second stage of stabilization – a decrease in the expression. Therefore, almost complete disappearance of MGMT protein in unmodified form (24 kDa) is observed. Conclusions. Statistically significant correlation between MGMT repair enzyme and mutations induction processes during mammalian cell adaptation and cell line establishment to in vitro was described.

Chromosome Studies of European Cyprinid Fishes: Cross-Species Painting Reveals Natural Allotetraploid Origin of a Carassius Female with 206 Chromosomes

A single female with 206 chromosomes and another 26 females with 156 chromosomes identified as Prussian carp, Carassius gibelio, and 5 individuals with 100 chromosomes identified as crucian carp, C. carassius, were sampled during field survey in one locality in the upper Elbe River. To identify the origin of females with high chromosome numbers, comparative karyotype analysis, GISH, with whole C. carassius DNA as probe and phylogenetic positions of sampled individuals revealed by cytochrome b mitochondrial marker were performed. GISH showed consistently bright labeling of 50 chromosomal elements out of 206, corresponding to the haploid chromosome number of C. carassius. The position of these females with high chromosome numbers in a reconstructed phylogenetic tree was within the clade of C. gibelio, documenting its affiliation to C. gibelio mitochondrial, i.e. maternal lineage. Our findings indicated that the mother of the female with high chromosome numbers was a gynogenetically reproducing 156-chromosome C. gibelio female and the father a bisexually reproducing C. carassius male. We, therefore, hypothesized that the C. gibelio × C. carassius allopolyploid female with 206 chromosomes arose by a mechanism of sperm genome addition to an unreduced egg of the mother.

Comparative karyotype and RAPD analysis for characterizing three varieties of Lycopersicon esculentum Mill.

Three tomato varieties (Lycopersicon esculentum Mill.) viz. BARI tomato-11, BARI tomato-2 and BARI tomato-3 released from Bangladesh Agriculture Research Institute (BARI) were characterized by karyotype analysis and RAPD markers. BARI tomato-11 and BARI tomato-2 were found to possess 2n = 24 metacentric chromosomes. On the other hand, 2n = 25 metacentric chromosomes were observed in BARI tomato-3 revealing a trisomic variety. The karyotype of the three varieties was very symmetric and each of the varieties showed specific and unique RAPD fingerprinting. Therefore, based on karyotype and RAPD analysis the three tomato varieties could be characterized. DOI: http://dx.doi.org/10.3329/bjb.v41i2.13439 Bangladesh J. Bot. 41(2): 149-154, 2012 (December)

A comparative analysis of karyotypes of three species of Macleaya—producers of a complex of isoquinoline alkaloids

Using a set of methods (C-banding, DAPI-staining, fluorescence hybridization in situ (FISH) with probes of 26S and 5S rDNA, and analysis of meiosis), the first comparative cytogenetic study of three species of Macleaya, producers of complex isoquinoline alkaloids, cordate Macleaya cordata (Willd.) R. Br. (2n = 20), small-fruited Macleaya microcarpa (Maxim.) Fedde (2n = 20) and Macleaya kewensis Turrill (2n = 20), was first carried out. On the basis of morphometric analysis, formulas of karyotypes were made for each species. Species ideograms for M. cordata, M. microcarpa, and M. kewensis were constructed taking into account the polymorphic variants of the C-banding patterns and indicating the location of 26S and 5S rDNA sites. A comparative study revealed that the karyotypes of M. microcarpa and M. kewensis have more in common with each other than with M. cordata. Analysis of meiotic chromosomes suggests of genetic stability of Macleaya genomes. The results of chromosome analysis were used to confirm the close relationship of Macleaya and to clarify their phylogenetic relationships.

Cytogenetic analysis ofMiscanthus × giganteusand its parent forms

This study aimed at comparative karyotype analysis and measurement of the nuclear DNA amount in giant miscanthus, Miscanthus × giganteus, and its hypothetical ancestors: eulalia grass (M. sacchariflorus) and porcupine grass (M. sinensis). The triploid chromosome number 2n = 57 in M. × giganteus and the diploid chromosome number 2n = 38 in the other species were confirmed. In the karyotype of giant miscanthus three satellite chromosomes were observed, whereas in M. sinensis there were two and in M. sacchariflorus probably four chromosomes of this type. In the first species 1–4 B-chromosomes were evidenced. The highest proportion of the C-banding/DAPI (4’,6-diamidino-2-phenylindole) positive heterochromatin was found in M. sinensis cv. Gracillimus, and the least in the M. sinensis M07 genome. The banding patterns observed in M. × giganteus resembled those observed in M. sacchariflorus. The 2C nuclear DNA content in M. × giganteus was 7.47 pg and in M. sacchariflorus it was 5.14 pg; two analysed lines ...

Geographical difference of chromosome aberrations between Japanese and American small cell lung cancer cell lines

Lung-cancer is the leading cause of cancer-related death worldwide. Cytogenetic analysis have been performed last two decades, but comparative analysis of karyotypes of small cell lung cancer (SCLC) from between Japan and America has not been precisely studied. Six Japanese and one American SCLC cell lines examined were hyperdiploid to neartetraploid with modal number of 52-91. These cells had a complex karyotype with more than 10 rearrangements. The karyotypic patterns were relatively consistent alterations involved long arm of chromosomes 1, 3, 7 and 11, and short arm of chromosomes 1 and 3. Higher rearrangements specially associated with translocations and deletions were observed in short and long arms of chromosomes 3 (3p21&3q25), and recurrently long arms of chromosome 7 (7q36 and 7q23). Although the chromosome of SCLC is too complex and G-banding analysis could not resolve all of many of the karyotypic abnormalities seen, several potentially site -specific abnormalities such as deletions of chromosome 3p, 7q and 3q, and amplifications of 3p, 7q, 1q, 11p, 2p and 12p in 6 SCLC cell lines established from chemotherapy resistant patients tumor cells. Losses of short arm chromosome 11 and 12 (11p, 12p) and long arm of chromosome 13 (13q), and amplifications of chromosomes 2, 11, 12, 13 and 19 (2p, 11p, 12p, 13q, 19p) were recurrently identified in the several cell lines, being different from published chromosomal abnormalities in American SCLC, which suggests geographical difference of SCLC karyotype. Also, these abnormal patters were largely different from non-small cell lung carcinoma (NSCLC). Unknown oncogenes localizing on these chromosome breakpoints for translocation or deletion region might be associated with the pathogenesis of SCLC. Present analysis can provide information on significant genes involved pathogenesis of SCLC.

First record of supernumerary (B) chromosomes in electric fish (Gymnotiformes) and the karyotype structure of three species of the same order from the upper Paraná River basin

Cytogenetic studies were performed on the species Apteronotus prope albifrons Linnaeus, 1766, Rhamphichthys hahni Meinken, 1937 and Brachyhypopomus gauderio Giora & Malabarba, 2009, collected in the upper Paraná River floodplain, Porto Rico (PR), Brazil. Apteronotus prope albifrons showed a diploid number of 2n=24 chromosomes for both sexes and a karyotype formula of 14m+2sm+2st+6a (FN=42). Besides the standard karyotype, three specimens had one to three extra microchromosomes with inter- and intra-individual variations, which suggested the occurrence of B chromosomes in the species. The chromosomal data of Rhamphichthys hahni, described here for the first time, consists of 50 chromosomes and a formula comprised of 20m+24sm+6a (FN=94). Brachyhypopomus gauderio specimens demonstrated 2n=42 chromosomes infemales, all acrocentric, and 2n=41 chromosomes in males, with 40 acrocentric and 1 medium-sized metacentric chromosome. These differences concern with a multiple system of sexchromosome determination X1X1X2X2/X1X2Y (FN=42) in Brachyhypopomus gauderio. The analysis of nucleolar organizer regions by Ag-NOR and FISH 18S banding revealed a simple NOR system in Apteronotus prope albifrons and Rhamphichthys hahni and a multiple NOR system in Brachyhypopomus gauderio, that is unusual for Gymnotiformes fishes. Constitutive heterochromatin was mainly found in the pericentromere region in most of the chromosomes of the three species, although each species had its own peculiarities. The B chromosomes in Apteronotus prope albifrons demonstrated heterochromatin positioned in the centromeric and telomeric regions whereas Rhamphichthys hahni presented conspicuous blocks of heterochromatin on the long arms in three submetacentric pairs. Brachyhypopomus gauderio showed blocks of heterochromatin on the long arm in the interstitial and telomere positions. The finding of B chromosomes in Apteronotus prope albifrons represents the first description of these elements in the Gymnotiformes order. Although the karyotype of this species is similar with that described for populations in the Amazon basin, the presence of B chromosomes could represent a specific characteristic of this population. A comparative analysis of karyotypes of Rhamphichthys hahni with other species of the genus showed a relatively conservative structure suggesting 2n=50 as a common number in this group. The karyotype of Brachyhypopomus gauderio, a new species, provides an important reference for future chromosome studies of the Brachyhypopmus Mago-Lecia, 1994, and it might be also significant for cytotaxonomy in this group. The cytogenetic data also demonstrate the need of more comparative cytogenetic studies in the families of the highly diversified and taxonomically difficult complex Gymnotiformes.

Comparative analysis of karyotypes among octoploid trititrigia and its original parents

Comparative analysis of karyotypes among octoploid trititrigia and its original parents

Major cytogenetic landmarks and karyotype analysis inDaucus carota and other Apiaceae

Karyotype analysis provides insights into genome organization at the chromosome level and into chromosome evolution. Chromosomes were marked for comparative karyotype analysis using FISH localization of rDNA genes for the first time in Apioideae species including taxa of economic importance and several wild Daucus relatives. Interestingly, Daucus species did not vary in number of rDNA loci despite variation in chromosome number (2n = 18, 20, 22, and 44) and previous publications suggesting multiple loci. All had single loci for both 5S and 18S-25S (nucleolar organizing region) rDNA, located on two different chromosome pairs. The 5S rDNA was on the short arm of a metacentric chromosome pair in D. crinitus (2n = 22) and D. glochidiatus (2n = 44) and on the long arm of a metacentric pair in other Daucus species, suggesting possible rearrangement of this chromosome. For other Apiaceae, from two (Apium graveolens), to three (Orlaya grandiflora), to four (Cuminum cyminum) chromosomes had 18S-25S rDNA sites. Variability for number and position of the 5S rDNA was also observed. FISH signals enabled us to identify 20-40% of the chromosome complement among species examined. Comparative karyotype analysis provides insights into the fundamental aspects of chromosome evolution in Daucus.