Karyotype Formula Research Articles

Karyomorphology of Seven Different Angiospermic Plants

The focus of this study is on the karyomorphological examination of seven angiospermic plants: Centaurea cyanus L. belonging to the Cynareae tribe; Coreopsis grandiflora Nutt. ex Chapm. and Eclipta prostrata (Linn.) Linn. from the Heliantheae tribe; Eupatorium adenophorum Spreng from the Eupatorie tribe; Gnaphalium affine D. Don. from the Inuleae tribe; Rhynchospermum verticillatum Reinw. from the Astereae tribe; and Tridax procumbens L within the Asteraceae family. Cytological analysis was used to assess the chromosome count and karyomorphology of all seven plants studied in central Nepal. The somatic chromosomal number found in this inquiry was 2n=24 for Centaurea cyanus, which has the karyotype formula M12+ m6+sm2+ st4. Similarly, 2n=26 was found for Coreopsis grandiflora, which has the karyotype formula M14+sm12 and 2n=22 for Eclipta prostrata which has the karyotype formula M14+sm6+st2.  The karyotype formula for Eupatorium adenophorum is M4+m12+sm26+st8 and 2n=50, while for Gnaphalium affine, it is M10+sm4, with a 2n=14 value. The karyotype formula for Rhynchospermum verticillatum is M4+ m8+ sm6 with 2n = 18. For Tridax procumbens L,  2n = 26 whose karyotype formula is M18+m4+sm2+ st2.The examined taxa's total length varied from 0.3 µm to 2.6 µm. Int. J. Appl. Sci. Biotechnol. Vol 12(1): 8-18.

A chromosome-level genome assembly of East Asia endemic minnow Zacco platypus

Zacco platypus is an endemic colorful freshwater minnow that is intensively distributed in East Asia. In this study, two adult female individuals collected from Haihe River basin were used for karyotypic study and genome sequencing, respectively. The karyotype formula of Z. platypus is 2N = 48 = 18 M + 24SM/ST + 6 T. We used PacBio long-read sequencing and Hi-C technology to assemble a chromosome-level genome of Z. platypus. As a result, an 814.87 Mb genome was assembled with the PacBio long reads. Subsequently, 98.64% assembled sequences were anchored into 24 chromosomes based on the Hi-C data. The chromosome-level assembly contained 54 scaffolds with a N50 length of 32.32 Mb. Repeat elements accounted for 52.35% in genome, and 24,779 protein-coding genes were predicted, with 92.11% were functionally annotated with the public databases. BUSCO analysis yielded a completeness score of 96.5%. This high-quality genome assembly provides valuable resources for future functional genomic research, comparative genomics, and evolutionary studies of genus Zacco.

First cytogenetic study of the Somphong’s rasbora (Trigonostigma somphongsi) (Perciformes, Cyprinidae), a critically endangered species in Thailand

The first chromosome study of Trigonostigma somphongsi (Meinken,1958) from Thailand. Specimens were collected from Pak Phli District, Nakhornnayok Province, central Thailand. The mitotic chromosomes were directly prepared from kidney tissues of two males and two females. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results shown that diploid chromosome number of T. somphongsi was 2n=50, the fundamental numbers (NF) were 92 in both male and female. The types chromosomes consisted of 10 metacentric, 20 submetacentric, 12 acrocentric and 8 telocentric chromosomes. The result also exhibited that the interstitial nucleolar organizer regions (NORs) were clearly observed at the short arm of chromosome pair 2. The karyotype formula could be deduced as: 2n (diploid) 50=10m+20sm+12a+8t.

Karyological analyses in several Algerian populations of six species of the genus Vicia L. (Fabaceae)

As part of the evaluation and valorization of plant genetic resources of fodder and pastoral interest in Algeria, seventeen (17) natural populations belonging to six (06) species of the genus Vicia (Vicia sativa, Vicia disperma, Vicia monardii, Vicia ohchroleuca, Vicia onobrychioides and Vicia lutea), originated from different ecological regions in the North-Eastern of the country, were considered. The populations have been the subject of mitotic and meiotic studies. Haploid and diploid numbers and chromosome measurements were determined. Original results were observed for the first time in some species. In fact, chromosome counts have revealed some new chromosome numbers. The first number (2n=14, n=7) was observed in the endemic subspecies of Algeria, V. ochroleuca subsp. atlantica and in the species Vicia onobrychioides. The second number (n=6) was observed in the species Vicia disperma. Within Vicia monardii, the three new chromosome numbers, previously observed only in mitosis by our research team, were confirmed for the first time through the present meiosis study (n=6, 7 and 8), indicating that they are A type chromosomes. The base number x=7 is the most frequently observed number in the six Vicia species. The observed chromosome numbers would be related to some ecological factors (altitude, rainfall) of the origin environment of the populations. Chromosome measurements and established karyotypes were determined for the first time in V. monardii, V. onobrychioides and V. ochroleuca subsp. atlantica. Chromosome size and karyotype formula are variable among the studied species and subspecies. Karyotypes vary from symmetrical to asymmetrical and the intrachromosomal asymmetry is higher than interchromosomal one. The new cytogenetic data would contribute to a better understanding of the evolution mechanism of the species in the genus Vicia L.

Chromosomal characterization mediated by karyomorphological analysis and differential banding pattern in fenugreek (Trigonella foenum-graecum L.): a neglected legume

Fenugreek or Trigonella foenum-graecum L. is a commercially important yet neglected crop of the family Fabaceae, with potent medicinal applications, and can treat several diseases as well. Conventional breeding studies for higher yields of commercial crops largely depend on chromosomal information of the particular species. Despite a number of cytological research being conducted on T. foenum-graecum, a complete characterization of its chromosomes has not been achieved due to the limitations of traditional karyotype analysis methods. A range of chromosomal markers are advantageous to characterize at full extent and identify individual chromosomes rather than relying on only physical metrics. Thus, in this study, in addition to giemsa staining, other approaches like fluorochrome and silver staining were used for the precise karyomorphological analysis of this species. Enzyme maceration and air drying (EMA) based fluorochrome banding with GC-specific stain Chromomycin A3 (CMA), and AT-specific stain 4’,6-diamidino-2-phenylindole (DAPI) applied for the first time for chromosome characterization. The results showed 2n = 16 chromosomes in metaphase cells, with karyotype formula of 2m+6sm. The unique banding pattern observed in the CMA/DAPI and AgNOR staining highlights the AT and GC-rich regions as well as the nucleolar organizer regions (NORs). All this crucial information can further assist in conducting breeding studies of more precision with simultaneously encouraging similar studies that need to be done in other unexploited species of importance.

Characterization of three citrullus lanatus (thunb.) Matsum. & nakai varieties by fluorescent chromosome staining and rapd analysis

Three commercial Citrullus lanatus varieties, namely Sonya, Kanya and Sweet black-2, were investigated with cyto-molecular techniques for characterization. Despite having similar somatic chromosome numbers and karyotype formulae (2n = 22), these three varieties had considerable diversities in Chromomycin A3 (CMA)- and 4′, 6-diamidino-2-phenylindole (DAPI)-banding patterns. The total somatic chromosomal length was longest in Sweet black-2 (71.44 ± 2.94 µm) and shortest in Sonya (42.31 ± 2.45 µm). Each variety's unique GC- and AT-rich chromatin composition was represented by a variety of numbers, percentages, and patterns of distribution. Eleven random primers were employed to evaluate the genetic diversity among three varieties. Each variety showed a distinct fingerprinting pattern with 88.72% polymorphism while having 10 of the same RAPD bands. Bangladesh J. Bot. 52(4): 1033-1040, 2023 (December)

Cytogenetics of Diphysa americana (Mill.) M.Sousa (Leguminosae-Papilionoideae-dalbergioid clade), a rare species from the coast of Oaxaca, Mexico

Diphysa Jacq. is an essentially Mexican and Central American genus that includes 21 species and only one cytogenetic report. In this work, a surface spread and air-drying method was used to obtain the karyotype of Diphysa americana (Mill) M.Sousa, a rare native tree that grows in a coastal town in the State of Oaxaca, Mexico. Metaphase cells showed a 2n = 20, consistent with the predominant diploid number in the dalbergioid clade. This number contrasts with a previously reported 2n = 16. The karyotypic formula 5m + 5sm, first proposed for a species of the genus, denotes a slightly asymmetric karyotype. The presence of secondary constrictions associated with satellites on the short arms of a pair of sm chromosomes and other cytogenetic parameters require studies in other species of the genus to verify their taxonomic utility. In addition, cells in prometaphase exhibited a circular fragment of unknown origin like that observed in a species of the genus Aeschynomene, also dalbergioid. This fragment could be related to extrachromosomal circular DNA (eccDNA) observed in other plants. Diphysa is a small, cytogenetically favorable genus, and further studies will exhibit the karyotypic diversity that underlies its diversification.

Fecundity, in vitro early larval development and karyotype of the zoonotic nematode Anisakis pegreffii

The in vitro life cycle of zoonotic helminths is an essential tool for -omic translational studies focused on disease control and treatment. Anisakiosis is an emerging zoonosis contracted by the ingestion of raw or undercooked fish infected with the third stage larvae (L3) of two sibling species Anisakis simplex sensu stricto (s.s.) and Anisakis pegreffii, the latter being the predominant species in the Mediterranean basin. Recently, in vitro culture of A. pegreffii has been developed to enable fast and large-scale production of fertile adults. However, the conditions for larval development from hatching to infective L3 were not fulfilled to complete the cycle. Herein, we used a Drosophila medium supplemented with chicken serum and adjusted different osmolarities to maintain the culture of L3 hatched from eggs for up to 17 weeks. The highest survival rate was observed in the medium with the highest osmolarities, which also allowed the highest larval exsheathment rate. Key morphological features of embryogenesis and postembryogenesis studied by transmission electron microscopy revealed that the excretory gland cell is differentiated already up to 48 h post-hatching. Extracellular vesicles and cell-free mitochondria are discharged between the two cuticle sheets of the second stage larvae (L2). Contemporarly cultivated, two populations of adult A. simplex s.s. and A. pegreffii reached an average production of 29,914.05 (± 27,629.36) and 24,370.96 (± 12,564.86) eggs/day/female, respectively. The chromosome spreads of A. pegreffii obtained from mature gonads suggests a diploid karyotype formula of 2n = 18. The development of a reliable protocol for the in vitro culture of a polyxenous nematode such as Anisakis spp. will serve to screen for much needed novel drug targets, but also to study the intricated and unknown ecological and physiological traits of these trophically transmitted marine nematodes.

Karyotype reexamination of Corydoras paleatus (Siluriformes) and a review of the cytogenetics of genus with a focus on the ribosomal genes

The subfamily Corydoradinae is the second largest among the callictids, comprising three genera, with Corydoras Lacépède, 1803 being the largest in the number of species. The genus Corydoras has been divided into five groups of species based on differences in diploid number, chromosomal morphology, and DNA content. Chromosome studies can provide crucial details on population differentiation. To better understand the diversification that occurs in this fish group, the current study based on such markers, presents data from a population of Corydoras paleatus from the first plateau of Paraná, putting them in a comparative scenario. The specimens studied has 2n=44 chromosomes with a karyotypic formula of 18m+26sm. Although conserved, this karyotypic structure shows variation in other populations of C. paleatus already studied, a consequence of chromosomal rearrangements that modify the morphology of chromosomes without modifying the 2n, such as centromeric repositioning. C-banding revealed conspicuous pericentromeric markings in metacentric pairs 4 and 8 and in submetacentric pairs 10 and 14, whose bands have been considered a chromosomal marker not only for C. paleatus but also for the genus. Fluorescent in situ hybridization (FISH) showed the major rDNA (45S) in the terminal region of the long arm of metacentric pair 5. Such location has already been described in other populations of C. paleatus, as they have also been mapped in short arms and with multiple patterns. The present study also provides a review of the genus Corydoras regarding the 2n, karyotypic formula and mainly regarding the number and location of the 45S and 5S rDNA, confirming a scenario in which chromosomal rearrangements have been modeling karyotypes of different populations and settling in the absence of gene flow, a consequence of vicariant events that occurred in the different basins.

Nuclear Phenotype and Karyotype Analysis in two Varieties of Lathyrus Sativus L.

Lathyrus sativus known as grass pea belongs to the family of Fabaceae commonly grown for human consumption and livestock feed throughout the world. This study based on the morphological features of the basic chromosome numbers and numerical characterization of the karyotypes using total chromosome length (TCL), arm ratio and total fraction frequency. Outcome of BARI Khesari-2 is more effective than BARI Khesari-3 on the basis of mitotic index, nuclear volume and interphase chromosome volume. Whereas, mitotic index directly relevant to cell division; when MI high than cell division rate will be high. The two varieties (BARI Khesari-2 and BARI Khesari-3) were found to possess 2n = 14 chromosomes. Karyotype analysis is an essential tool for studying the genetic constitution of any organism. In this investigation, we found the karyotype formula of BARI Khesari-2 is 7L 4m + 2sm + 1st and BARI Khesari-3 is 7L 2m +3sm + 2st. Chromosome morphology showed a variation in the chromosome length, chromosome structure and centromere position of the accessions. Presence of sub-terminal chromosome in both varieties shows asymmetric karyotype which indicates advanceness. The variation in L. sativus may be regarded as having evolution and adaptive significance. J. Bio-Sci. 30(2): 59-65, 2022

Cytogenetic Study of Five Varieties of Callisia repens (Jacq.) L. (Commelinaceae) from Laos

Cytogenetical studies were carried out on five varieties of Callisia repens, i.e., turtle vine, green, pink lady, gold, and Bianca. The morphological characteristics of all five varieties differed in leaf shape and color of the plant. All five varieties have the same chromosome number, 2n = 12, and the fundamental number (NF) = 24. The number of metacentric (m), submetacentric (sm), and subtelocentric (st) chromosomes was related to the discrepancies between the various karyotypes that were found. The formula for each of the karyotypes was 2m + 2sm + 8st (turtle vine), 2m + 10st (green), 8m + 4st 14 (pink lady), 2m + 4sm + 6st (gold), and 2m + 2sm + 8st (Bianca). Therefore, all five strains had asymmetrical karyotypes. The chromosome number of C. repens has been reported previously, but this is the first report of karyotype variation among the varieties. Furthermore, principal component analysis (PCA) of the karyotype formula was able to distinguish C. repens ‘pink lady’, C. repens ‘green’, and C. repens ‘gold’, but it was unable to differentiate between C. repens ‘Bianca’ and C. repens ‘turtle vine’. Additionally, PCA conducted on the centromeric index (CI) and the leaf colors of the five varieties of C. repens successfully separated all of them. Therefore, the prominent morphological traits and karyotype information of the five varieties of C. repens from Laos can be used to distinguish between them.

Chromosome evolution in Iberolacerta, a genus that deviates from the standard karyotype formula of Lacertidae

This paper describes the preparation of flow-sorted chromosome paints from the Iberian Rock lizard Iberolacerta monticola, exemplifying their subsequent use in cross-species comparisons of chromosome painting. We carried out comparative analyses of chromosome evolution in the congeneric species I. galani and I. bonnali, as well as in two other species of Lacertini (Lacerta schreiberi and Timon lepidus) whose sex chromosomes were also studied through comparative genomic hybridization. Most species of Lacertini possess a diplod number of 2n = 38, with 36 acrocentric macrochromosomes and 2 microchromosomes. However, the nine species included in the genus Iberolacerta do not possess microchromosomes. Furthermore, very conspicuous differences from the standard Lacertini karyotype were observed in the three Pyrenean species of this genus, which included several biarmed metacentrics and a Z1Z2W multiple sex-chromosome system. With the possible exception of L. schreiberi, all the species of the family Lacertidae described to date appear to share homologous Z chromosomes, which date back to the last common ancestor of the whole group. We provide conclusive evidence that L. schreiberi should no longer be considered an exception to this rule, and demonstrate that the loss of microchromosomes in Iberolacerta was produced by their fusion to a middle-sized chromosome. Furthermore, we show that the multiple sex-chromosome system of the Pyrenean species of Iberolacerta originated from the fusion of the ancestral W chromosome with one of the shortest autosomes, and provide additional evidence of the fast evolution of DNA sequences linked to the W chromosome in Lacertini.

Karyotype and Phylogenetic Relationship Analysis of Five Varieties and Cultivars of Zanthoxylum armatum Based on Oligo-FISH.

Green prickly ash (Zanthoxylum armatum) has edible and medicinal value and is an economically significant plant in many countries. Z. armatum has many cultivars and varieties with similar phenotypes that are difficult to distinguish via traditional methods. In this study, we utilized oligo-FISH to distinguish five varieties and cultivars of Z. armatum on the basis of three oligonucleotide probes of 5S rDNA, (AG3T3)3, and (GAA)6. Karyotype analysis of the five varieties and cultivars of Z. armatum showed that the Z. armatum 'Tengjiao' karyotype formula was 2n = 2x = 98m with karyotype type 1C and an arm ratio of 4.3237, including two pairs of 5S rDNA signals and five pairs of (GAA)6 signals. The karyotype formula of Z. armatum 'Youkangtengjiao' was 2n = 2x = 128m + 8sm with karyotype type 2B and an arm ratio of 3.5336, including three pairs of 5S rDNA signals and 17 pairs of (GAA)6 signals. The karyotype formula of Z. armatum var. novemfolius was 2n = 2x = 134m + 2sm with karyotype type 1C and an arm ratio of 5.5224, including two pairs of 5S rDNA signals and eight pairs of (GAA)6 signals. The karyotype formula of Z. armatum 'YT-03' was 2n = 2x = 2M + 128m + 4sm + 2st with karyotype type 2C and an arm ratio of 4.1829, including three pairs of 5S rDNA signals and nine pairs of (GAA)6 signals. The karyotype formula of Z. armatum 'YT-06' was 2n = 2x = 126m + 10sm with cytotype 2B and an arm ratio of 3.3011, including three pairs of 5S rDNA signals and two pairs of (GAA)6 signals. The five varieties and cultivars of Z. armatum had (AG3T3)3 signals on all chromosomes. The chromosomal symmetry of Z. armatum 'Tengjiao' was high, whereas the chromosomal symmetry of Z. armatum 'YT-03' was low, with the karyotypes of the five materials showing a trend toward polyploid evolution. The phylogenetic relationship between Z. armatum 'Tengjiao' and Z. armatum var. novemfolius was the closest, while that between Z. armatum 'YT-03' and Z. armatum 'YT-06' was closer than with Z. armatum 'Youkangtengjiao' according to oligo-FISH. The results provided a karyotype profile and a physical map that contributes to the distinction of varieties and cultivars of Z. armatum and provides strategies for distinguishing other cultivated species.

Canidae Taksonlarının Karyotip Simetri/Asimetri İndeksi (S/AI) ile Karşılaştırılması

The family Canidae is placed in the suborder Caniformia in the order Carnivora. There are both domestic and wild species in Canidae. The family consists of at least 35 wild species in 13 genera. The number of chromosomes in Canidae is divided into 2 groups. (i) The chromosome numbers are 2n = 54, 66, 74, 76, and 78 with mostly acrocentric autosomes. (ii) The chromosome numbers are 2n = 34, 36, 38, and 50 with mostly metacentric and submetacentric autosomes. The formula S/AI measure the symmetry or asymmetry of karyotype in higher animals and humans. In this study, the formula was applied to the Canidae species. After obtaining karyotype formulae with a detailed literature review, S/AI data and karyotype types of 25 female taxa and 17 male taxa were determined. According to the S/AI values, a dendrogram was drawn showing karyological variations among the taxa. The results will contribute to the phylogeny of mammals.

Chromosomal analysis of Sander lucioperca (L., 1758) (Perciformes: Percidae) from Turkey

Sander lucioperca (pikeperch) is a percid fish species of high commercial value and potential for being aquaculture in Turkey. However, karyological studies are deficient for population of Turkey. So, the aim of this study is to carry out diploid chromosome number, karyotype formula, fundamental arm number and chromosomal banding properties (with C-banding and Ag-NOR staining) of S. lucioperca. Specimens of S. lucioperca were captured from Konya, Turkey and alive specimens carried to the laboratory. Chromosome obtaining was provided by using air-drying technique from the head kidney. Chromosome slides were prepared and banding procedures were applied. Result of the analysis, diploid chromosome number was found as 48 and karyotype of the pikeperch consist of 32 biarmed and 16 uniarmed chromosomes. Constitutive heterochromatin regions were observed on the pericentromeres of some of the chromosomes. Ag-NORs were determined on one pair of submetacentric chromosome. This report is the first that determines chromosomal properties of S. lucioperca from Turkey. This study may contribute the cytogenetic information of this species.

A comparative karyological study of Helianthemum (Cistaceae): karyotype size, karyotype symmetry and evolution of chromosome number

In this study we assessed karyotype size and symmetry for a comprehensive taxonomic and geographic representation of Helianthemum and reconstructed chromosome number evolution in the genus. Using root tips, we photographed mitotic metaphase spreads to obtain chromosome number, total haploid (monoploid) length of the chromosome set (THL), karyotype formula, Stebbins’ classification of karyotype asymmetry, interchromosomal coefficient of variation of chromosome length (CVCL) and intrachromosomal mean centromeric asymmetry (MCA) using MATO (Measurement and Analysis Tools). We found that shifts in chromosome number are not a major driver in the evolution of Helianthemum, whose chromosome number evolved at a constant rate of single chromosome gain or loss. Karyotype asymmetry is very low and little variable in all taxonomic categories studied, with a predominance of metacentric and submetacentric small to medium-sized chromosomes about 3 μm at the genus level. However, total karyotype length varies from 16.91 μm to 47.84 μm at the species level, with a cytogenetic signature that is not conserved within subgenera and most sections. Overall, H. subg. Plectolobum shows both the longest and the most symmetrical karyotypes. We hypothesize that the variation in karyotype size in Helianthemum is likely a consequence of chromosome rearrangements that have occurred under selective pressures.

Oligo-FISH of Populus simonii Pachytene Chromosomes Improves Karyotyping and Genome Assembly.

Poplar was one of the first woody species whose individual chromosomes could be identified using chromosome specific painting probes. Nevertheless, high-resolution karyotype construction remains a challenge. Here, we developed a karyotype based on the meiotic pachytene chromosome of Populus simonii which is a Chinese native species with many excellent traits. This karyotype was anchored by oligonucleotide (oligo)-based chromosome specific painting probes, a centromere-specific repeat (Ps34), ribosomal DNA, and telomeric DNA. We updated the known karyotype formula for P. simonii to 2n = 2x = 38 = 26m + 8st + 4t and the karyotype was 2C. The fluorescence in situ hybridization (FISH) results revealed some errors in the current P. simonii genome assembly. The 45S rDNA loci were located at the end of the short arm of chromosomes 8 and 14 by FISH. However, they were assembled on pseudochromosomes 8 and 15. In addition, the Ps34 loci were distributed in every centromere of the P. simonii chromosome in the FISH results, but they were only found to be present in pseudochromosomes 1, 3, 6, 10, 16, 17, 18, and 19. Our results reveal that pachytene chromosomes oligo-FISH is a powerful tool for constructing high-resolution karyotypes and improving the quality of genome assembly.

Cytogenetic evidence of hybridization in Prosopis alba, P. hassleri, and P. fiebrigii in the semiarid-humid Chaco transition

Hybridization is a common and widespread phenomenon in vascular plants, leading to genetic exchange between related species. Interspecific hybridization has been extensively reported in Prosopis, a key genus of the Gran Chaco Americano, when species grow in sympatry or have adjacent distributions. Here, we performed a cytogenetic study in a hybrid zone of Prosopis alba, P. hassleri, and P. fiebrigii in southern South America. We characterized the karyotypes of pure species and the putative interspecific hybrids using chromosome fluorescent banding. Two karyotypes according to the heterochromatin pattern were identified, one corresponding to P. alba and the other to P. hassleri and P. fiebrigii; hybrid individuals presented P. alba or P. hassleri/P. fiebrigii karyotypes. The karyotypic formula and the number of nucleolar organizer regions were the same for all the studied morphotypes. Chromosome similarity among different species of the genus allows a continued hybridization and introgression between species and lends support to the hypothesis of a relatively recent diversification of Prosopis. Studying karyotype variation within a population could be a novel approach to the cytogenetic study of hybrids in the future.

First report of chromosome and karyological analysis of Gekko nutaphandi (Gekkonidae, Squamata) from Thailand: Neo-diploid chromosome number in genus Gekko

The karyotypes of red-eyed Gecko are not reported yet. Herein, we describe the karyotypes of red-eyed Gecko (Gekko nutaphandi Bauer, Sumontha & Pauwels, 2008) from Thailand. Gecko chromosome preparations were directly conducted from bone marrow and testis. Chromosomal characteristics were analyzed by Giemsa staining, Ag-NOR banding as well as fluorescence in situ hybridization (FISH) using microsatellites d(GC)15 probe. The results showed that the number of diploid chromosomes is 2n=34, while the fundamental number (NF) is 46 in both males and females. The types of chromosomes were 4 large metacentric, 6 large submetacentric, 2 medium telocentric, 2 small metacentric and 20 small telocentric chromosomes. The results of conventional Giemsa staining presented the diploid chromosome number differentiation even in the same genus. NORs are located at the secondary constriction to the telomere on the long arm of chromosome pair 5. There are no sex differences in karyotypes between males and females. FISH with d(GC)15 sequences were also displayed at the telomeres of most other chromosomes. We found that during metaphase I the homologous chromosomes showed synapsis, which can be defined as 19 ring bivalents and 17 haploid chromosomes (n=17) at metaphase II as a diploid species. The karyotype formula is as follows: 2n (34) = L4m+L6sm+M2t+S2m+S20t.

Intraspecific karyomorphological and genome size variations of in vitro embryo derived Iranian endemic Asafoetida (Ferula assa-foetida L., Apiaceae)

Asafoetida (Ferula assa-foetida L.) is one of the endemic medicinal plants in Iran. Analysis of karyomorphology and 2Cx DNA measurements (monoploid genome size) of 18 Iranian endemic Ferula assa-foetida populations were performed. The in vitro embryo-derived root tips were examined for karyological studies, via technique of squash and stain with 2% (w/v) aceto-orcein. Seeds of the Ferula samples and leaves of Solanum lycopersicum as standard reference (2C DNA = 1.96 pg) were stained with propidium iodide (PI), using flow cytometric (FCM) technique. All the studied populations were diploids (2n = 2x = 22) with mean chromosome length (CL) of 3.95 μm, varied from 3.05 μm (P7) to 4.94 μm (P18). The mean total chromosome volume (TCV) was 0.98 μm3, ranged from 0.47 μm3 (P7) to 1.57 μm3 (P3). Two-typed chromosomes (“m”, “sm”) formed three classes of karyotype formula. Karyotypes were mostly symmetrical and fell in 1A and 2A Stebbins category. The monoploid genome size of Iranian endemic Ferula assa-foetida populations is being stated for the first time; its mean value was 4.51 pg, ranged from 4.09 (P4) to 4.69 pg (P16). Intraspecific karyomorphological and genome size variations were clearly confirmed in studied Ferula assa-foetida.