Pairs Of Metacentric Chromosomes Research Articles

Chromosome numbers and karyotype features of Phlomis olivieri Benth. (Lamiaceae) from Iran

AbstractChromosome numbers were determined in ten accessions ofPhlomis olivieriBenth. (Lamiaceae). The seeds were collected from natural habitats in the west of Iran. Chromosome numbers of all accessions were 2n=2x=20. The chromosomes of accessions were metacentric or submetacentric, ranging in length from 2.66 to 8.604 μm. According to the average values of ten accessions, the karyotype of this species consists of 10 pairs of metacentric chromosomes. An ideogram was depicted for the species. This is the first report on the chromo-some number and karyotype analysis ofP. olivierifrom Iran.

Fluorescence in situ Hybridization Karyotype Analysis of Seven Platycodon grandiflorum (Jacq.) A. DC. Cultivars

Platycodon grandiflorum has long been cultivated for its medicinal properties and economic value, prompting crop improvement programs that have spurred the development of new cultivars. However, limited cytogenetic information is available for this species, especially for different P. grandiflorum cultivars. Karyotype analysis via fluorescence in situ hybridization (FISH) provides essential information about chromosome count and the localization of DNA sequences, thus providing a chromosome-level understanding of genome structure. Here, we carried out triple-color FISH karyotype analysis of various P. grandiflorum (Jacq.) A. DC. cultivars using 5S and 45S ribosomal DNA (rDNA) and telomeric repeat probes. The karyotype is composed of 2n = 18 chromosomes consisting of seven pairs of metacentric chromosomes, one pair of submetacentric chromosomes, and one pair of subtelocentric chromosomes. The chromosome length ranges from 1.92 to 4.98 μm. One pair of 5S rDNA loci was observed on either the intercalary or pericentromeric regions of chromosome 3. All cultivars showed 45S rDNA signals on chromosome 9, and in two closely related cultivars, one additional pair of 5S rDNAs co-localized with these 45S rDNAs. Arabidopsis -type telomeric repeats were observed in most telomeric regions of the chromosomes in all seven cultivars. Our data lay the foundation for future cytogenetic studies of P. grandiflorum focusing on breeding and the elucidation of its genome structure.

Are Pericentric Inversions Reorganizing Wedge Shell Genomes?

Wedge shells belonging to the Donacidae family are the dominant bivalves in exposed beaches in almost all areas of the world. Typically, two or more sympatric species of wedge shells differentially occupy intertidal, sublittoral, and offshore coastal waters in any given locality. A molecular cytogenetic analysis of two sympatric and closely related wedge shell species, Donax trunculus and Donax vittatus, was performed. Results showed that the karyotypes of these two species were both strikingly different and closely alike; whilst metacentric and submetacentric chromosome pairs were the main components of the karyotype of D. trunculus, 10–11 of the 19 chromosome pairs were telocentric in D. vittatus, most likely as a result of different pericentric inversions. GC-rich heterochromatic bands were present in both species. Furthermore, they showed coincidental 45S ribosomal RNA (rRNA), 5S rRNA and H3 histone gene clusters at conserved chromosomal locations, although D. trunculus had an additional 45S rDNA cluster. Intraspecific pericentric inversions were also detected in both D. trunculus and D. vittatus. The close genetic similarity of these two species together with the high degree of conservation of the 45S rRNA, 5S rRNA and H3 histone gene clusters, and GC-rich heterochromatic bands indicate that pericentric inversions contribute to the karyotype divergence in wedge shells.

Chromosome Evolution in the Free-Living Flatworms: First Evidence of Intrachromosomal Rearrangements in Karyotype Evolution of Macrostomum lignano (Platyhelminthes, Macrostomida).

The free-living flatworm Macrostomum lignano is a hidden tetraploid. Its genome was formed by a recent whole genome duplication followed by chromosome fusions. Its karyotype (2n = 8) consists of a pair of large chromosomes (MLI1), which contain regions of all other chromosomes, and three pairs of small metacentric chromosomes. Comparison of MLI1 with metacentrics was performed by painting with microdissected DNA probes and fluorescent in situ hybridization of unique DNA fragments. Regions of MLI1 homologous to small metacentrics appeared to be contiguous. Besides the loss of DNA repeat clusters (pericentromeric and telomeric repeats and the 5S rDNA cluster) from MLI1, the difference between small metacentrics MLI2 and MLI4 and regions homologous to them in MLI1 were revealed. Abnormal karyotypes found in the inbred DV1/10 subline were analyzed, and structurally rearranged chromosomes were described with the painting technique, suggesting the mechanism of their origin. The revealed chromosomal rearrangements generate additional diversity, opening the way toward massive loss of duplicated genes from a duplicated genome. Our findings suggest that the karyotype of M. lignano is in the early stage of genome diploidization after whole genome duplication, and further studies on M. lignano and closely related species can address many questions about karyotype evolution in animals.

Karyotype analysis of Piptanthus concolor based on FISH with a oligonucleotides for rDNA 5S

Abstract The karyotype of Piptanthus concolor was analysed via fluorescence in situ hybridization (FISH) using oligonucleotide probe for ribosomal DNA (rDNA) (5S rDNA, 41 bp). P. concolor had 2n = 18 chromosomes. The karyotype was composed of 3 pairs of metacentric chromosomes (including one pair of satellites), 3 pairs of submetacentric chromosomes, and 3 pairs of subtelocentric chromosomes. 5S rDNA loci were detected in 8 chromosome pairs. The density and location of signals for both 5S rDNA varied among individual chromosomes. High-intensity 5S signals were detected in the short arms of chromosomes 7 and 8, and weak signals were also detected in the long arms of the same chromosomes. For the satellite chromosomes, 17 and 18, the 5S rDNA signal was located at the end of the long arm. The third pair of chromosomes, 9 and 10, also significantly differed from other chromosomes with respect to the 5S rDNA signals observed in the subterminal region. The fourth pair of chromosomes, 11 and 12, had no 5S rDNA signal. The other pairs of chromosomes also exhibited individual signals. Our results provide information that may be beneficial for future cytogenetic studies and could contribute to the physical assembly of the Piptanthus genome.

Karyotype and Fluorescence In Situ Hybridization Analysis of 15 Lilium Species from China

Karyotype comparison and fluorescence in situ hybridization (FISH) were conducted to analyze the wild Lilium species distributed in China. The karyotype results revealed that all species except Lilium lancifolium (2n = 3X = 36) were diploid and had two pairs of metacentric or submetacentric chromosomes. The karyotypes of all species are similar. FISH analysis revealed that there are 5–12 45S rRNA gene loci dispersed on the chromosomes of the 14 diploid species, and 15 45S rRNA gene loci were detected in the triploid species L. lancifolium. Most of the FISH signals were detected on the long arms and the centromeric regions. Three samples of L. brownii [Hubei, China (lat. 31°28′N, long. 110°23′E); Liaoning, China (lat. 40°07′N, long. 124°19′E); and Guangxi, China (lat. 25°06′N, long. 107°27′E)] showed very similar chromosome patterns in both the karyotype and the FISH analyses, further demonstrating that these samples belonged to the same species. L. brownii is widely distributed in China from latitude 25°06′N to 40°07′N, indicating that it is highly adaptable to the environment.

Molecular cytogenetic differentiation of paralogs of Hox paralogs in duplicated and re-diploidized genome of the North American paddlefish (Polyodon spathula)

BackgroundAcipenseriformes is a basal lineage of ray-finned fishes and comprise 27 extant species of sturgeons and paddlefishes. They are characterized by several specific genomic features as broad ploidy variation, high chromosome numbers, presence of numerous microchromosomes and propensity to interspecific hybridization. The presumed palaeotetraploidy of the American paddlefish was recently validated by molecular phylogeny and Hox genes analyses. A whole genome duplication in the paddlefish lineage was estimated at approximately 42 Mya and was found to be independent from several genome duplications evidenced in its sister lineage, i.e. sturgeons. We tested the ploidy status of available chromosomal markers after the expected rediploidization. Further we tested, whether paralogs of Hox gene clusters originated from this paddlefish specific genome duplication are cytogenetically distinguishable.ResultsWe found that both paralogs HoxA alpha and beta were distinguishable without any overlapping of the hybridization signal - each on one pair of large metacentric chromosomes. Of the HoxD, only the beta paralog was unequivocally identified, whereas the alpha paralog did not work and yielded only an inconclusive diffuse signal. Chromosomal markers on three diverse ploidy levels reflecting different stages of rediploidization were identified: quadruplets retaining their ancestral tetraploid condition, semi-quadruplets still reflecting the ancestral tetraploidy with clear signs of advanced rediploidization, doublets were diploidized with ancestral tetraploidy already blurred. Also some of the available microsatellite data exhibited diploid allelic band patterns at their loci whereas another locus showed more than two alleles.ConclusionsOur exhaustive staining of paddlefish chromosomes combined with cytogenetic mapping of ribosomal genes and Hox paralogs and with microsatellite data, brings a closer look at results of the process of rediploidization in the course of paddlefish genome evolution. We show a partial rediploidization represented by a complex mosaic structure comparable with segmental paleotetraploidy revealed in sturgeons (Acipenseridae). Sturgeons and paddlefishes with their high propensity for whole genome duplication thus offer suitable animal model systems to further explore evolutionary processes that were shaping the early evolution of all vertebrates.

Morphology, anatomy and karyology of endangered Turkish endemic Physoptychis haussknechtii Bornm. (Brassicaceae) from Central Anatolia

Abstract In this study, the morphology, anatomy, pollen morphology, leaf and seed micromorphology and karyology of the Turkish endangered endemic Physoptychis haussknechtii were investigated in detail for the first time. The species was studied in terms of detailed morphology. Basal leaves are narrowly spatulate and cauline leaves are linear to oblanceolate; both leaves are covered with flattened stalked five-armed trichomes. Raceme length was found to be up to 6 cm and 9 cm in the flowering and fruiting stages, respectively. Sepals are linear-oblong, rarely elliptic with obtuse to subacute apex. Petals are spatulate with emarginate apex. Some morphological characteristics such as dimensions of cauline leaves and ovary and length of pistil were measured for the first time. In an anatomical study, root, stem, basal leaf and cauline leaf were examined. The anatomical results showed that the plants have secondary growth in roots, primary growth in stems, amphistomatic and equifacial basal and cauline leaves with anisocytic stomata. Pollen grains are radial symmetrical, isopolar and tricolpate. The ratio of polar axis to equatorial diameter is 1.16, and pollen shape is subprolate. Exine sculpturing is reticulate under light microscope and scanning electron microscope. Seeds are obovatesuborbicular, compressed and pale brown. The chromosome number of P. haussknechtii was defined to be 2n=16. The karyotype formula of P. haussknechtii consists of five metacentric chromosome pairs and three submetacentric chromosome pairs.

Differentiation of Nolana and Sclerophylax (Solanaceae) by means of heterochromatin and rDNA patterns

ABSTRACTWithin Solanaceae, Nolana L. f. and Sclerophylax Miers are two genera that have deserved special attention because of their rare anatomical characteristics. However, they are poorly known from the cytogenetic perspective. In order to discuss their chromosome features in an evolutionary context, classical staining, chromomycin A3/4′-6-diamidino-2-phenylindole (CMA/DAPI) fluorescent banding and in situ hybridisation (FISH) with probes for the 18-5.8-26S and the 5S rDNA loci were applied to root tips of germinating seeds. All the species presented the chromosome number 2n = 24. Karyotypes were highly symmetric, with most chromosomes being metacentric and with a maximum of three submetacentric pairs in N. divaricata. The CMA/DAPI banding technique, assayed for the first time in Sclerophylax, showed CMA+/DAPI− bands associated with nucleolar organiser regions (NORs) in the first metacentric chromosome pair in each species. The FISH technique (applied to four species of Sclerophylax and, for the first time, in one species of Nolana) showed that the 18-5.8-26S loci coincide with CMA+/DAPI− bands. Three Sclerophylax species presented two pairs of 5S signals, whereas S. adnatifolia showed three. The rDNA loci resulted as asyntenic in Sclerophylax, but were localised in the same chromosome in N. divaricata. Despite the morphological peculiarities of Nolana and Sclerophylax, the chromosome number and karyotype features are consistent with the position of the two genera within the ‘x = 12 clade’, while the number and position of rDNA loci established the chromosome rearrangements, suggesting different evolutionary pathways with respect to their closest relatives, Lycium and Jaborosa.

The karyotype of the great sculpin, Myoxocephalus polyacanthocephalus (Pallas, 1814) (Pisces: Cottidae), from the Russian part of the species range

The karyotype of the great sculpin, Myoxocephalus polyacanthocephalus (Pallas, 1814) (Pisces: Cottidae) from the Sea of Okhotsk and the Sea of Japan has been studied for the first time. The karyotype is stable; it consists of 40 chromosomes (4 metacentric, 2 submeta-subtelocentric, 20 subtelocentric, and 14 acrocentric chromosomes); the number of chromosomal arms is 44 + 2. Nucleolar organizer regions (NOR) are found in the telomeric region of the arm in one homologue of a pair of small metacentric chromosomes, using the Ag-NOR banding technique. A comparative analysis of the karyotype of M. polyacanthocephalus and the karyotypes of other Myoxocephalus species (M. stelleri, M. brandtii, M. jaok, M. ochotensis, and M. scorpius) has been carried out based on the main karyotype characters, as well as on the number and localization of NORs. The identified differences make it possible to differentiate the studied species, whereas the general traits indicate their taxonomic proximity.

Detecting Mechanisms of Karyotype Evolution in Heterotaxis (Orchidaceae).

The karyotype is shaped by different chromosome rearrangements during species evolution. However, determining which rearrangements are responsible for karyotype changes is a challenging task and the combination of a robust phylogeny with refined karyotype characterization, GS measurements and bioinformatic modelling is necessary. Here, this approach was applied in Heterotaxis to determine what chromosome rearrangements were responsible for the dysploidy variation. We used two datasets (nrDNA and cpDNA, both under MP and BI) to infer the phylogenetic relationships among Heterotaxis species and the closely related genera Nitidobulbon and Ornithidium. Such phylogenies were used as framework to infer how karyotype evolution occurred using statistical methods. The nrDNA recovered Ornithidium, Nitidobulbon and Heterotaxis as monophyletic under both MP and BI; while cpDNA could not completely separate the three genera under both methods. Based on the GS, we recovered two groups within Heterotaxis: (1) "small GS", corresponding to the Sessilis grade, composed of plants with smaller genomes and smaller morphological structure, and (2) "large GS", corresponding to the Discolor clade, composed of plants with large genomes and robust morphological structures. The robust karyotype modeling, using both nrDNA phylogenies, allowed us to infer that the ancestral Heterotaxis karyotype presented 2n = 40, probably with a proximal 45S rDNA on a metacentric chromosome pair. The chromosome number variation was caused by ascending dysploidy (chromosome fission involving the proximal 45S rDNA site resulting in two acrocentric chromosome pairs holding a terminal 45S rDNA), with subsequent descending dysploidy (fusion) in two species, H. maleolens and H. sessilis. However, besides dysploidy, our analysis detected another important chromosome rearrangement in the Orchidaceae: chromosome inversion, that promoted 5S rDNA site duplication and relocation.

Evidence for Karyotype Polymorphism in the Free-Living Flatworm, Macrostomum lignano, a Model Organism for Evolutionary and Developmental Biology.

Over the past decade, the free-living flatworm Macrostomum lignano has been successfully used in many areas of biology, including embryology, stem cells, sexual selection, bioadhesion and aging. The increased use of this powerful laboratory model, including the establishment of genomic resources and tools, makes it essential to have a detailed description of the chromosome organization of this species, previously suggested to have a karyotype with 2n = 8 and one pair of large and three pairs of small metacentric chromosomes. We performed cytogenetic analyses for chromosomes of one commonly used inbred line of M. lignano (called DV1) and uncovered unexpected chromosome number variation in the form of aneuploidies of the largest chromosomes. These results prompted us to perform karyotypic studies in individual specimens of this and other lines of M. lignano reared under laboratory conditions, as well as in freshly field-collected specimens from different natural populations. Our analyses revealed a high frequency of aneuploids and in some cases other numerical and structural chromosome abnormalities in laboratory-reared lines of M. lignano, and some cases of aneuploidy were also found in freshly field-collected specimens. Moreover, karyological analyses were performed in specimens of three further species: Macrostomum sp. 8 (a close relative of M. lignano), M. spirale and M. hystrix. Macrostomum sp. 8 showed a karyotype that was similar to that of M. lignano, with tetrasomy for its largest chromosome being the most common karyotype, while the other two species showed a simpler karyotype that is more typical of the genus Macrostomum. These findings suggest that M. lignano and Macrostomum sp. 8 can be used as new models for studying processes of partial genome duplication in genome evolution.

Karyological analysis of Korean endemic land snail,Koreanohadra kurodana(Gastropoda: Bradybaenidae)

AbstractThe karyotypes of the Korean endemic land snail, Koreanohadra kurodana, were investigated using the air-drying method. The diploid chromosome number for this species was 2n = 58, including 23 metacentric chromosome pairs, five submetacentric chromosome pairs and one telocentric chromosome pair; therefore, the fundamental number was FN = 56. Observed chromosomes ranged from 2.1 to 8.5% in total length and the mean total length of the chromosomes in the diploid was 95.5 ± 1.34 μm.

Chromosomal mapping of tandem repeats in the Yesso Scallop, Patinopecten yessoensis (Jay, 1857), utilizing fluorescence in situ hybridization.

Construction of cytogenetic maps can provide important information for chromosome identification, chromosome evolution and genomic research. However, it hasn’t been conducted in many scallop species yet. In the present study, we attempted to map 12 fosmid clones containing tandem repeats by fluorescence in situ hybridization (FISH) in the Yesso scallop Patinopecten yessoensis (Jay, 1857). The results showed 6 fosmid clones were successfully mapped and distributed in 6 different pairs of chromosomes. Three clones were respectively assigned to a pair of metacentric chromosomes, a pair of submetacentric chromosomes and a pair of telocentric chromosomes and the remaining 3 clones showed their loci on three different pairs of subtelocentric chromosomes by co-hybridization. In summary, totally 8 pairs of chromosomes of the Yesso scallop were identified by 6 fosmid clones and two rDNA probes. Furthermore, 6 tandem repeats of 5 clones were sequenced and could be developed as chromosome specific markers for the Yesso scallop. The successful localization of fosmid clones will undoubtedly facilitate the integration of linkage groups with cytogenetic map and genomic research for the Yesso scallop.

FISH-mapping of the 5S rDNA locus in chili peppers (Capsicum-Solanaceae).

We present here the physical mapping of the 5S rDNA locus in six wild and five cultivated taxa of Capsicum by means of a genus-specific FISH probe. In all taxa, a single 5S locus per haploid genome that persistently mapped onto the short arm of a unique metacentric chromosome pair at intercalar position, was found. 5S FISH signals of almost the same size and brightness intensity were observed in all the analyzed taxa. This is the first cytological characterization of the 5S in wild taxa of Capsicum by using a genus-derived probe, and the most exhaustive and comprehensive in the chili peppers up to now. The information provided here will aid the cytomolecular characterization of pepper germplasm to evaluate variability and can be instrumental to integrate physical, genetic and genomic maps already generated in the genus.

Karyotype analysis and chromosome banding ofUpeneus moluccensis(Bleeker, 1855) from the north-eastern Mediterranean

Chromosome number, morphology and location of the nucleolus organizer region (NOR) are useful cytological characters for taxonomic and evolutionary studies. The karyotype of Upeneus moluccensis from the north-eastern Mediterranean was investigated through conventional Giemsa staining, Ag-NOR staining, C-banding and GTG-banding techniques. The results showed 2n = 44 (FN = 46), 2m + 2st + 40a chromosomes and four NORs. Two telomeric C-band regions were observed on a metacentric and subtelocentric chromosome pair. On the basis of the chromosome morphology, the GTG and C-banding pattern, it is hypothesized that Upeneus moluccensis is more primitive than the Mediterranean native fish species, Mullus barbatus and Mullus surmuletus. In this study, the cytogenetic characterization of U. moluccensis has been carried out for the first time.

Karyotypic characterization of the pike, Esox lucius from the south Caspian Sea basin

The karyotype of pike from Anzali lagoon in the south Caspian Sea basin have been investigated by examining metaphase chromosomes spreads obtained from gill epithelial and kidney cells. The chromosomes spreads were stained with 7% Giemsa solution for 15 min and examined under a light microscope. Appropriate metaphase plates were photographed in order to prepare karyotype. All specimens had a diploid number of 50 chromosomes, with a karyotype constituted by 12 metacentric‏, 24 submetacentric, 14 subtelocentric and fundamental number (NF) of 86. The largest chromosome in this species was a pair of metacentric chromosomes. Based on type of chromosomes, the karyotype of the species differed from the findings of previous studies, which could be attributed to the existence of different populations for this species. Despite the conserved diploid number, the data on the karyotype structure help characterize the cytogenetic profile of this species.

Cytogenetic data on the threatened leafcutter ant Atta robusta Borgmeier, 1939 (Formicidae: Myrmicinae: Attini)

The karyotype of the threatened ant species Atta robusta is described so as to establish the evolutionary relationships of this taxon with other leafcutter ants. Standard Giemsa staining, C-banding, NOR banding, fluorochromes CMA3/DAPI, Hsc-FA technique and Fluorescence in situ Hybridization (FISH) using 18S rDNA probe were conducted on a population from Aracruz, state of Espírito Santo, Brazil, allowing for comparisons with data available on Atta and other fungus-growing ant species. The diploid chromosome number observed for A. robusta was 2n=22, and the karyotypic formula was 18m+2sm+2st. Heterochromatic blocks were observed in the centromeric region of most chromosomes, where one pair of metacentric chromosomes is characterized by a GC-rich heterochromatic band in the interstitial region of its long arm. The detection of 18S rDNA using FISH confirmed the presence of single NOR for A. robusta. This is the first report of rDNA 18S detection using FISH for leafcutter ants. The cytogenetic results of this study confirm the information available for Atta and allow us to confirm the conserved chromosome number, morphology and banding pattern within the genus for the taxa studied to date, which included species from three out of the four groups of Atta indicated by molecular data. The accumulation of cytogenetic data on fungus-growing ants enhances the understanding of the genomic evolutionary patterns of Atta, since it belongs to a group of recent origin between the most well studied ants. Cytogenetic data does not indicate restrictions in relocation or reintroduction in areas where populations were extinct due to the conserved karyotype. This study allows for cytogenetic comparison of A. robusta with other ants of Atta, emphasizing the importance of chromosomal information for species conservation.

<b>Karyotypic characterization of <i>Capsicum</i> sp. accessions

This study aimed to determine the chromosome number and the karyotype of Capsicum annuum, Capsicum chinense, Capsicum frutencens and Capsicum baccatum accessions in the active Capsicum sp. genebank at the Federal University of Piaui (BGC-UFPI). These species have great economic importance throughout the world, and their cytogenetic characterization can inform taxonomy and lead to improvement in the genus. Karyotypes were obtained from the rootlet meristems of the studied accessions using the squash method and Giemsa staining. The chromosome number 2n=2x=24 was verified for each of the four species. Chromosomal polymorphisms were observed for the C. frutencens accession BGC 37, which presented 12 pairs of metacentric chromosomes instead of 11 pairs of metacentric chromosomes and 1 submetacentric chromosome pair present in other accessions. In the accessions BGC 01 and BGC 37, secondary constrictions were observed in the 1 and 12 as well as in the 6 and 11 homologs, respectively. The karyotypes of the studied species were asymmetrical among themselves. The results obtained in this study confirm the high genetic diversity previously described in the literature for this genus.

Karyological, morphological, and phylogenetic diversification in Leucocoryne Lindl (Allioideae, Amaryllidaceae)

The genus Leucocoryne (Amaryllidaceae) comprises approximately 15 species and is the only genus of the tribe Ipheieae endemic to the western region of Chile in sclerophyll and arid winter-rainfall biomes in the Andes. To better understand the karyotype diversification of this genus, nine species of Leucocoryne were analyzed in terms of their chromosome number and morphology, CMA and DAPI heterochromatic bands, distribution of rDNA sites, and their molecular phylogenetic relationships. Based on phylogenetic analyses Leucocoryne was divided in four clades: I (L. alliacea and L. conferta); II (L. dimorphopetala and L. narcisoides); III (L. coquimbensis, L. macropetala, L. appendiculata, L. talinensis, L. angustipetala, L. purpurea, and L. violacescens); and IV (L. vittata, L. ixioides, L. foetida, and L. pauciflora). The species were diploids with 2n = 10 (6M + 4A) or tetraploids with 2n = 18 (14M + 4A)/2n = 19 (13M + 6A). 45S rDNA sites were co-localized with CMA+/DAPI− bands on the short arms of acrocentric chromosomes in all species. 5S rDNA sites were observed on one, two, or four pairs of metacentric chromosomes per species. Estimations of the ancestral karyotype suggest that 2n = 10 (6M + 2A) with one 5S rDNA site per monoploid complement was the plesiomorphic condition of the genus Leucocoryne. Increases in number of 5S rDNA sites in the same species associated with biome shifts from sclerophyll to arid winter-rainfall region occurred independently in clade II and clade III. The two species of clade II retained the six fertile stamens (plesiomorphic condition) in contrast to the other Leucocoryne species that reduced to only three functional stamens. Based on these findings, we discuss the role of environmental change on the diversification of this group.