Karyological studies of four endemicCentaureaL. species
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In this paper, four endemic Centaurea species were investigated in terms of their chromosome numbers and karyomorphology. The chromosomal counts confirmed the results of previous reports, that the genus Centaurea has different basic chromosome numbers. Centaurea yaltirikii and Centaurea demirizii are diploid taxa. Centaurea yaltirikii has 2n = 18 chromosomes, and therefore has a basic chromosome number of nine, which is common in the genus Centaurea. A local endemic species, Centaurea demirizii has 2n = 16 chromosomes and a different basic chromosome number of x = 8, and this basic number is relatively rare for Centaurea. Centaurea leptophylla and Centaurea saligna are tetraploid with 2n = 36 chromosomes. We found predominance of chromosomes being metacentric and submetacentric. The results increase our karyological knowledge of these species. Moreover, this paper gives short taxonomic and morphologic notes to complement the information provided by Flora of Turkey with regards to the studied species.Keywords:
Centaurea
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The karyotype of fifteen Leucocoryne taxa was studied, assessing characteristics such as chromosome morphology and size, secondary constriction location, and asymmetry level. Two groups of Leucocoryne taxa were described based on chromosome number (2n = 10 and 2n = 18) and karyotype asymmetry. The haploid karyotype formula for the group 2n = 10 was 3m + 2st (or 2t), whereas for the group 2n = 18 was 7m + 2st (or 2t). Such results corroborate the karyotype descriptions previously carried out for some taxa of the genus. Leucocoryne taxa showed a high resemblance in chromosome morphology, but inter-specific differences were found in mean chromosome size. These data and previous studies based on gross chromosome morphology support Crosa's hypothesis, which suggests that the cytotype 2n = 10 is diploid and perhaps ancestral, whereas that the cytotype 2n = 18 is tetraploid but with an additional chromosome fusion being probably a derived status.
Secondary constriction
Morphology
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Cytogenetic characterization by karyotyping and determination of DNA content by flow cytometry of five species of Chrysolaena (Vernonieae, Asteraceae) was performed. This is the first study of nuclear DNA content realized in the genus. The 2C-values were compared with the ploidy level and the total karyotype length (TKL) of each species. Mitotic analysis revealed a base chromosome number x = 10 for all entities and different ploidy levels, from diploid (2n = 2x = 20) to octoploid (2n = 8x = 80). All species showed bimodal karyotypes composed of metacentric and submetacentric chromosomes. The average chromosome size (ML) varied from 1.86 μm to 2.70 μm, while the TKL ranged from 18.65 μm to 80.55 μm. The intrachromosomal asymmetry index (A1) varied from 0.27 to 0.38, while the interchromosomal asymmetry index (A2) ranged from 0.19 to 0.25. A new cytotype is reported for the first time for C. propinqua. Accessory chromosomes found in C. verbascifolia, C. cognata, C. flexuosa, and C. propinqua are also reported as new.
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Nuclear DNA
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The chromosome number of 10 species and karyotypes of 9 species of them in the genus Caragana from China were analyzed in this paper,and the results are as follows:C.roborovskyi,2n=16=10m(2SAT)+6sm;C.erinacea,2n=16=10m+6sm;C.densa,2n=16=10m(2SAT)+6sm;C.acanthophylla,2n=16=12m+4sm;C.stipitata,2n=16=10m+6sm;C.opulens,2n=16=12m(2SAT)+4sm;C.leucophloea,2n=32=22m(4SAT)+10sm;C.camilli-schneideri,2n=32=20m(4SAT)+12sm,C.tragacanthoides,2n=32=20m(2SAT)+10sm+2st+2B.For two populations of C.licentiana,only chromosome numbers are reported here,both with 2n=4x=32,being tetraploid.From the results we inclined to suppose that the karyotype of chromosomes in Caragana is not so much differentiated,and if differentiated it always follows by some morphological characters.The diploid and tetraploid are the main ploidy level of this genus,with 2n=16(diploid)or 2n=32(tetraploid).Triploid was found only in C.sinica,and hexaploid was seen only in C.ussuriensis.Those species with diploid chromosomes mostly are pinnate-leaved,and are mainly distributed in Estern Asia where probably is the genus' ancestral areal,but those species with tetraploid chromosomes are majorly with digitate leaflets,and incline to adapt to desert areas in Northwestern China.
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Karyotypic variability of plants was evaluated in 17 populations of six species of the genus Chondrilla ( C. ambigua Fisch. , C. brevirostris Fisch, et Mey., C. laticoronata Leonova , C. canescens Kar., Kir., C. juncea , C. pauciflora Ledeb.) in the Astrakhan, Voronezh and Saratov regions, the Republic of Kalmykia, and Western Kazakhstan. It is maintained that C. ambigua is a strict diploid (2n = 2x = 10) species, while its close relative - C. pauciflora - is a strict triploid (2n = 3x = 15) taxon. The research demonstrates that the plants of the apomictic taxa C. brevirostris , C. canescens , C. juncea and C. laticoronata are characterized by the genomic instability in the form of chromosome instability which results in these species’ mixed-ploidy populations.
Apomixis
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Chromosome numbers and karyotypes of Corylopsis glabrescens and C. gotoana in the Hamamelidaceae were investigated. Corylopsis glabrescens was diploid with 2n=24=14m+8sm+2st, while C. gotoana was tetraploid with 2n=48=36m+8sm+4st. The karyotype of the diploid C. glabrescens was different from that of the diploid C. pauciflora previously reported in Japan, suggesting a heterogeneous origin of the two species. The karyotype of the tetraploid C. gotoana seemed to share a homogeneous karyotype composition with the hexaploid C. spicata previously reported in Japan.
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The chromosome numbers and karyomorphology of 32 accessions are examined, representing 12 species of Anaphalis DC. (Asteraceae) from the Hengduan Mountains of south-western China, which is most likely the biologically richest temperate region in the world. A total of 11 species are newly reported, and the highest chromosome number, 2n = 84, was observed in the Helichrysum–Anaphalis–Pseudognaphalium group for the first time. Within Anaphalis, the basic number x = 14 was confirmed. Only two species (A. flavescens and A. pachylaena) are diploid with 2n = 28. Tetraploidy is observed in seven species. Diploid–polyploid complexes are found in A. aureopunctata, A. bicolor, and A. nepalensis, especially for A. nepalensis with a series of polyploidy levels from di-, tetra-, to hexaploid. In addition to the tetraploid origin of the genus, a second polyploidisation is suggested as the predominant event in the chromosome evolution of Anaphalis from the Hengduan Mountains. The karyotypes of all observed samples are 2A or 2B, except for one population of A. bicolor as 1B according to Stebbins' asymmetry classification of karyotypes. The asymmetry index (AI) values change from 1.49 to 3.65. However, there is no evidence of association between chromosome evolution (i.e. polyploidy frequency and karyotype variation) and the altitudes in Anaphalis.
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SUMMARYThe somatic chromosomes of eight Vernonia species (Asteraceae) from Brazil, Paraguay and Argentina were analyzed. First chromosome counts are presented for V. coriacea Less. (2n=32 = 20m + 10sm + 2st), V. dura Mart, ex DC. (2n=32 = 22m + 10sm), V. eriolepis Gardn. (2n=32 = 22m + 8sm + 2st), V. grandiflora Less. (2n=64 = 50m + 14sm) and V. onopordioides Baker (2n=32 = 18m + 2m-sm + 10sm + 2st). Besides, the chromosome numbers of V. brevifolia Less. ((2n=32 = 22m + 10sm) and V. sellowii Less. (2n=62 = 40m + 20sm + 2st) are also confirmed. The number found in V. saltensis Hieron (2n=64 = 48m + 16sm) support the occurrence of two cytotypes within the species, one diploid (2n=32) and the other tetraploid (2n=64). The eight species revealed certain differences between their karyotypes principally in formula, total length and asymmetry level, which coincides with earlier studies for South American taxa. Satellites were commonly found on submetacentric or subtelocentric pairs, being also variable in morphology and location. Chromosomal data here reported and the already available for the genus indicate that the evolution of Vernonia have been followed for a decrease in number and size of the chromosomes.
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Abstract The description of the karyotype features and idiogram in Grindelia squarrosa (Pursh) Dunal (Asteraceae), an invasive plant in Romania, are reported here for the first time. The diploid chromosome number is 2n=2x=12, in agreement with the data published for the other species of the genus. The karyomorphological data show that the complements of the studied genotypes have small chromosomes (mean chromosome length is X̅±SE=2.56±0.10 μm, and mean length of haploid complements is X̅±SE=15.33±0.69 μm, with a range of variability comprised between 12.87-17.51 μm). The karyotypes are made up of six pairs of metacentric and submetacentric chromosomes, with an identical formula of the diploid complement: KF=2n=12=8m+ 2sm + 2sm-SAT. Satellites are located on the short arms of the chromosomes of pair III. The karyotypes show a relatively high level of intra-specific uniformity as well as similar symmetry patterns (R=1.29-1.53; TF%=38.78-41.57%; AsI%=54.54-57.61%; A1 = 0.24- 0.32; A2=0.08-0.16), belonging to 1A and 2A classes of symmetry. The small size of the chromosomes, the presence of only two chromosome morphometric types, and the preponderance of metacentrics confer a relatively high degree of symmetry to the karyotypes studied.
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A new Centaurea L. (Asteraceae) species from Turkey is described and illustrated. Centaurea dursunbeyensis Uysal & Köse exists on limestone crevices in ancient Dursunbey Forest (Balikesir) in western Anatolia. It belongs to C. sect. Phalolepis (Cass.) DC., and taxonomically its closest relatives are C. aphrodisea Boiss. and C. cadmea Boiss. Diagnostic morphological characters from very similar taxa are provided, and a key is provided that includes related species of sect. Phalolepis from Turkey. The geographical distribution of the new species and species of other related taxa of the same section are mapped. The chromosome number of C. dursunbeyensis, 2n = 36, counted in root tips, is also reported and illustrated.
Centaurea
Eudicots
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Fifteen chromosome counts of six Artemisia taxa and one species of each of the generaBrachanthemum , Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x=9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.
Artemisia
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