Karyotype analysis in South American species of Myrtaceae

In Myrtaceae (Myrteae), the diploid chromosome number 2 n  = 2 x  = 22 is the most common, although variations of ploidy level occur, with some triploid (2 n  = 3 x  = 33) and tetraploid (2 n  = 4 x  = 44) records. Karyotype details in this group are scarce because the chromosomes are small (< 2 μm). In this work, we carried out a karyotypic analysis of 15 species of Myrtaceae grouped in different subtribes and genera. Measurements of chromosome length (long arm, L ; short arm, S ) were taken and several karyotypic parameters were calculated for each species. The karyotypes in fleshy-fruited taxa (Myrteae) were more varied than in the other previously analysed dry-fruited group ( Eucalyptus , Eucalypteae), in which the chromosomes were exclusively metacentric.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155 , 571–580.     

Chromosome numbers in plant taxa endemic to the Balearic Islands

Mitotic chromosome numbers are reported from 20 vascular plant taxa that are endemic to the Balearic Islands and poorly known cytogenetically. The chromosome numbers of Arenaria grandiflora L. ssp. glabrescens (Willk.) G. López & Nieto Feliner (2 n  = 44), Dianthus rupicola Viv. ssp. bocchoriana L. Llorens & Gradaille (2 n  = 30), Solenopsis minuta (L.) C. Presl. ssp. balearica (E. Wimm.) Meikle (2 n  = 28), Romulea asumptionis Font Quer & Garcías Font (2 n  = 56), Scutellaria balearica Barceló (2 n  = 22) and Galium balearicum Briq. (2 n  = 22) have been determined for the first time. A new chromosome number was found in two populations of Helictotrichon crassifolium (Font Quer) Holub (2 n  =  c. 98) suggesting that this species is a high polyploid (14 x ), in contrast to an earlier report of a lower chromosome count (2 n  = 12 x  = 84). Cytogenetic observations suggest that Naufraga balearica Constance & Cannon has a diploid chromosome complement of 2 n  = 20, with 0–2 accessory chromosomes. The banded karyotype (chromomycin A₃) of Crepis triasii (Cambess.) Fries was determined for individuals belonging to eight populations from three islands. Two chromomycin A₃-positive regions were recorded in the diploid complement. These are present on the telomeric regions of the shortest subtelocentric chromosomes. This species is karyologically stable in chromosome number, karyotype and fluorochrome-banding pattern among populations from separate islands.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 219–228.     

Chromosomes of four species in three genera of Commelinaceae from China and their systematic implications

Chromosomes of four species in three genera of Commelinaceae from China were examined. Spatholirion longifolium had 2 n  = 20. This small genus is considered to be of a possible polyploid origin based on x  = 5, a basic number shared by its closest ally, the monospecific genus Streptolirion , with its only species having 2 n  = 10. The two genera were found to be very different from each other in their karyotypic constitution. The differences in both chromosome number (2 n  = 20 vs. 10) and karyotypic constitution support their separation as two independent genera. The remaining three species, Amischotolype hispida , Porandra ramosa and P. scandens , all had 2 n  = 36. In view of the occasional occurrence of 2 n  = 18 in the African Coleotrype , a genus very close to Amischotolype and Porandra in gross morphology, these three species are all very probably polyploid based on x  = 9. The high degree of karyotypic similarity of the three genera also strongly indicates their close affinity and supports their placement in the subtribe Coleotrypinae. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 152 , 399–403.     

Chromosome counts in Asian Artemisia L. (Asteraceae) species: from diploids to the first report of the highest polyploid in the genus

This work comprises 24 reports of chromosome numbers in 24 Artemisia L. species from Asia. Ten are included in the subgenus Dracunculus Besser and the rest belong to other subgenera. Seven counts are new reports, 14 are consistent with scarce previous ones, and three contribute new ploidy levels. That carried out in A. medioxima reports the highest ploidy level ever counted for the genus (16 x ). There is only one species with x  = 8 as the basic chromosome number. In the remaining x  = 9-based species, ploidy levels range from 2 x to 16 x , illustrating the great role played by polyploidy in the evolution of the genus.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 301–310.     

Chromosome studies on some Asteraceae from South America

Mitotic or meiotic chromosome numbers for 42 accessions belonging to 39 species of different genera of Asteraceae were determined. First chromosome counts are reported for one genus ( Gymnocoronis ), 14 species, and one variety. These are as follows: Solidago chilensis var. megapotamica (2 n  = 2 x  = 18), Chromolaena barbacensis (2 n  = 3 x  = 30), Chromolaena christieana (2 n  = 3 x  = 30), Chromolaena hirsuta (2 n  = 4 x  = 40), Chromolaena verbenacea ( n  = 20 II, 2 n  = 4 x  = 40), Disynaphia multicrenulata (2 n  = 2 x  = 20), Gymnocoronis spilanthoides var. subcordata (2 n  = 2 x  = 20), Mikania thapsoides (2 n  = 4 x  = 68), Stevia commixta (2 n  = 2 x  = 22), Porophyllum brevifolium (2 n  = 4 x  = 44), Viguiera rojasii (2 n  = 2 x  = 34), Pterocaulon angustifolium (2 n  = 2 x  = 20), Gochnatia haumaniana (2 n  = 4 x  = 44), Senecio ostenii (2 n  = 4 x  = 40), Senecio pinnatus (2 n  = 8 x  = 80), and Lepidaploa amambaia (2 n  = 2 x  = 28). Chromosome numbers differing from those reported previously in the literature were found in Campuloclinium macrocephalum (2 n  = 2 x  = 20), Melanthera latifolia (2 n  = 4 x  = 60), Chrysolaena flexuosa (2 n  = 2 x  = 20), and Cyrtocymura cincta (2 n  = 4 x  = 40). The relevance of the results is discussed in relation to the available data for each of the analysed taxa. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 153 , 221–230.     

Cytological studies on the Sino-Himalayan endemic Anisodus and four related genera from the tribe Hyoscyameae (Solanaceae) and their systematic and evolutionary implications

Cytological studies were carried out on eight species of five genera ( Anisodus , Atropanthe , Hyoscyamus , Mandragora and Przewalskia ) in the tribe Hyoscyameae (Solanaceae). First chromosome counts were reported in six species: Anisodus luridus , A. acutangulus , A. tanguticus , A. carniolicoides , Atropanthe sinensis and Mandragora caulescens , all with 2 n  = 8 x  = 48. Two records, for Hyoscyamus niger (2 n  = 2 x  = 34) and Przewalskia tangutica (2 n  = 4 x  = 44), were also confirmed. All species studied showed the proximal type of mitotic prophase chromosome condensation pattern. Three types of interphase nuclei were recognized: the round prochromosome type for Anisodus , Atropanthe and Mandragora , the rod prochromosome type for Przewalskia and the complex chromocentre type for Hyoscyamus . The cytological data supported the close relationship of all four species of Anisodus . Evidence from the interphase nuclei and chromosome base numbers supported the traditional classification of Hyoscyameae into two groups, i.e. Physochlaina praealta + Hyoscyamus (complex interphase type and x  = 7, 14, 17) and Przewalskia + Atropanthe + Anisodus + Scopolia + Atropa + Mandragora (prochromosome type and x  = 6, 11). Polyploidy is found in most species of the tribe in the Himalayan–Hengduan Mountains, as well as in the Mediterranean region, west–central Asia and eastern Asia. It seems that it probably occurred very early in Hyoscyameae evolution, before the uplift of the Himalayan–Hengduan Mountains. The Himalayan orogeny might have played a minor role in the polyploid evolution of plants in this tribe.  © 2005 The Linnean Society of London. Botanical Journal of the Linnean Society , 2005, 147 , 457–468.     

Chromosome numbers in Hieracium and Pilosella species (Asteraceae) from the Iberian Peninsula and the Balearic Islands

Mitotic chromosome numbers are reported from 16 Hieracium and two Pilosella species from the Iberian Peninsula and the Balearic Islands that are little known cytogenetically. The chromosome numbers of Hieracium aragonense Scheele (2 n  = 27, 36), H. compositum Lapeyr. (2 n  = 27), H. murcandidum G. Mateo (2 n  = 27), H. spathulatum Scheele (2 n  = 27), H. segurae Mateo (2 n  = 27), H. teruelanum Mateo (2 n  = 27), H. valentinum Pau (2 n  = 27), Pilosella pseudovahlii (De Retz) Mateo (2 n  = 18), and P. tardans (Peter) Sójak (2 n  = 36) were determined for the first time. New cytotypes were detected in H. cordifolium Lapeyr. (2 n  = 27) and H. loscosianum Scheele (2 n  = 36). The karyotype of the studied species was similar in overall morphology and comprised metacentric and submetacentric chromosomes; secondary constrictions (up to two) were detected in the chromosome complements of some species.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 311–320.     

Chromosome numbers in the tribe Anthemideae (Asteraceae) from north-east Anatolia

Twenty-two chromosome counts of 19 taxa in the tribe Anthemideae of the family Asteraceae are reported from north-east Anatolia, Turkey. The taxa belong to the subtribes Achilleinae (four Achillea taxa), Anthemidinae (five Anthemis taxa), Artemisiinae (two Artemisia species), Leucantheminae (one Lecanthemum species), Matricariinae (two Tripleurospermum species) and Tanacetinae (five Tanacetum taxa). Six counts are new reports, seven are not consistent with previous counts, and the remainder are confirmations of very limited previous data. Most of the populations of Anthemideae studied have the basic number x  = 9, with ploidy levels ranging from 2 x to 7 to 8 x , but dysploidy is also present, with one diploid species, Artemisia austriaca , having x  = 8.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 203–211.     

Cytotaxonomy of Lychnophoriopsis Sch.Bip. and Paralychnophora MacLeish species (Asteraceae: Vernonieae: Lychnophorinae)

The genera Lychnophoriopsis and Paralychnophora are endemic to Brazilian 'campo rupestre' in the States of Minas Gerais and Bahia. To analyse the status of the cytotaxonomy of these genera, we carried out chromosome counts on several species. Two chromosome numbers were obtained for four species of Paralychnophora : 2 n  = 36 and 2 n  = 38. For three species of Lychnophoriopsis , only 2 n  = 36 was observed. The chromosome size (1.0–2.58 µm) and morphology (mainly metacentric, with some submetacentric) were analysed in four species of Paralychnophora and showed relative constancy .   © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 109–114.     

Chromosome numbers and karyotypes of South American species and populations of Hypochaeris (Asteraceae)

One hundred and thirty-seven new chromosome counts are reported from 104 populations of 26 native South American taxa of Hypochaeris (Asteraceae, Lactuceae), together with two invasive Mediterranean species: H. glabra and H. radicata . First reports are provided for seven taxa ( H. alba , H. cf. eremophila , H. caespitosa , H. hookeri , H. parodii , H. patagonica and H. pinnatifida ) and one new ploidy level is reported (diploid for H. incana , so far known only as a tetraploid). Including the results of this study, the chromosomes of 39 of the c . 50 Hypochaeris species known from the New World have now been counted. Most species are diploid with 2 n  = 2 x  = 8 and have bimodal, asymmetrical karyotypes. Tetraploidy (2 n  = 4 x  = 16) is reported here for the first time in H. caespitosa . Infra-specific polyploidy (probably autopolyploidy) is reported in H. incana and H. taraxacoides , both cases including infra-populational cytotype mixtures (2 x and 4 x ). Polyploidy is now known from eight South American Hypochaeris species ( c . 16%). Basic karyotype analyses allow the placement of the newly counted taxa into previously proposed but slightly modified groupings and provide the framework for further molecular cytogenetic analyses. The reported findings suggest that chromosomal change in South American Hypochaeris , in contrast to Old World species, has not involved aneuploidy, but polyploidy and/or more subtle changes in chromosome length, perhaps via satellite DNA amplification/deletion or activity of retroelements, and rDNA reorganization.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 49–60.     

Chromosome variation in the genus Pinellia (Araceae) in China and Japan

The chromosome numbers of 23 populations belonging to seven species of Pinellia Tenore were counted. The basic chromosome number of all the species studied was x  = 13, and the previously reported basic numbers x  = 9 and x  = 14 in P. ternata and P. cordata were not confirmed. Chromosome numbers of 2 n  = 26 in P. polyphylla and 2 n  = 78 in P. integrifolia are reported for the first time. Heptaploid (7 x ) and nonuploid (9 x ) are new ploidy levels reported for P. ternata , and hexaploid for P. cordata. Taxonomic, phylogenetic and phytogeographical inferences are made for the genus. Particular attention was given to P. ternata , the most widely distributed species in the genus, and considerable variation of chromosome number was found in its different populations. Based on chromosome studies of 11 populations of P. ternata , together with 12 populations reported in previous studies, the lower reaches of the Yangze River are identified as its centre of origin. From there it dispersed, with generation of hexaploid, heptaploid, octoploid and nonuploid forms.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 449–455.     

Karyotype evolution in the genus Boronia (Rutaceae)

New chromosome counts are reported for Boronia clavata 2 n  = 14, B. heterophylla 'Near White' 2 n  = 15, B.  'Carousel' 2 n  = 16, B. deanei 2 n  = 22, B. chartacea 2 n  = 32, B. keysii 2 n  = 32, B. pilosa 2 n  = 44, B. anethifolia 2 n  = 36 and B. citriodora 2 n  = 108. Studies in 20 genotypes of 18 species and one interspecific hybrid revealed that they are highly complex in terms of chromosome number, ploidy level, chromosomal length, karyotype constitution and asymmetry. Karyotype analysis indicated that Boronia taxa with high chromosome numbers are primitive and those with lower numbers are derived. The basic chromosome number for this genus is suggested to be x = 18. Analysis of chromosome number, variations of total chromosome length (TCL) and average chromosome length (ACL), Nombre Fondamental (NF) and karyotype asymmetry suggest that dysploid reduction is the major mechanism in Boronia karyotype evolution. Chromosomal rearrangements might also have been involved. Origin, chromosome number changes and spread of Boronia are discussed in relation to the species divergence and the geological and climatic changes of the Australian continent.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 309–320.     

Ploidy variation in Buddleja L. (Buddlejaceae) in the Sino-Himalayan region and its biogeographical implications

The chromosome numbers of 27 populations of Buddleja , comprising 14 species, were counted. The basic chromosome number of all species was x  = 19, confirming previous reports. Different ploidy levels (2 n  = 38, 76, 114, 228) were observed in these taxa, representing diploids, tetraploids, hexaploids, and dodecaploids, respectively. The chromosome numbers of B. yunnanensis , B. brachystachya , and B. macrostachya are reported for the first time. The tetraploid 2 n  = 76 is a new ploidy level for B. myriantha . Particular attention was given to B. macrostachya , because of the variation in morphology and ploidy level between isolated populations of this species. Two types of interphase nuclei were recognized: the complex chromocentre type in B. macrostachya and the simple chromocentre type in the other species. Biogeographically, most of the polyploidy in the Asiatic species occurs in the Sino-Himalayan region. It seems to be associated with the uplift of the Himalayan Mountains, the orogeny of this region playing an important role in the evolution of polyploidy in these taxa.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 305–312.     

Ploidal levels in the arctic-alpine polyploid Draba lactea (Brassicaceae) and its low-ploid relatives

Ploidal level information is of particular importance in intricate polyploid complexes such as in arctic-alpine Draba . Relative DNA content is reported for the tetra- and hexaploid D. lactea and seven of its low-ploid relatives. Flow cytometry was used to study 200 plants from 93 populations, the screening based on relative fluorescence. Absolute DNA content was determined by Feulgen densitometry for 13 plants from seven species, and reference chromosome numbers were determined in 12 plants (1–3 per species) representing six species. The plants grouped into diploids (2 n  = 16), tetraploids (2 n  = 32), hexaploids (2 n  = 48), and two triploids. Each ploidal level showed a linear increase in relative DNA content, pointing to a relatively recent polyploid origin. The diploid level was confirmed in D. nivalis, D. subcapitata, D. fladnizensis , and D. lonchocarpa. Draba palanderiana , reported previously as di-, tetra- and octoploid, was diploid in all investigated accessions. Hexa- and tetraploids were observed in D. lactea , in approximately the same ratio (8 : 1) as reported previously. The ploidal levels of the Central Asian D. altaica and D. turczaninovii are reported here for the first time as diploid and tetraploid, respectively.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 333–347.     

Chromosome study of the fern genus Cyrtomium (Dryopteridaceae)

Cyrtomium (Dryopteridaceae) is an Asiatic genus comprising about 40 species characterized by having anastomosing veins that form areolae with included veinlets. Twelve chromosome counts representing 11 taxa were made in the present study. The chromosome numbers of six species endemic to China are reported for the first time: C. uniseriale , 2 n  = 164; C. guizhouense , 2 n  = 82; C. shingianum , n  = 82, 2 n  =  c .164; C. chingianum , 2 n  = 164; C. urophyllum , 2 n  = 82 and C. aequibasis , 2 n  = 123. The results were used to show that (1) C. uniseriale should be reduced to varietal status under C. balansae ; (2) subseries Balansana is not closely related to any other Cyrtomium species and should be separated from Cyrtomium ; and (3) C. guizhouense and C. lonchitoides are basal groups when subseries Balansana is not considered. These results were also supported by morphology. A high level of differentiation is a distinct characteristic in Cyrtomium . The genus has two reproductive types: sexual and apogamous. Sexual species are distributed mostly in China. Southwestern China is a modern diversity centre of Cyrtomium , with 80.6% of known species occurring there. Many species are endemic, most of which are sexual tetraploids or apogamous triploids. Both the apogamous reproductive type and polyploid species are adaptions to limestone habitats.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 221–228.     

Occurrence of tetraploid and octoploid cytotypes in Senecio jacobaea ssp. jacobaea (Asteraceae) in Pannonia and the Carpathians

Four different cytotypes have been reported for Senecio jacobaea L. ssp. jacobaea throughout Europe, with the most common occurrence of tetraploids (2 n  = 40). Here we present a survey of previously published chromosome number data on this subspecies and its geographical distribution, and focus on populations from Pannonia and the Carpathians. Two ploidy levels have been determined in the study area, using chromosome counting and flow cytometry: tetraploid (2 n  = 40) and octoploid (2 n  = 80). Fifty-one populations originating from Slovakia, Austria, the Czech Republic, Hungary, Ukraine and Romania have been analysed. Multivariate morphometric analyses have been performed on 39 populations to study morphological differentiation between these two cytotypes. Despite slight morphological tendencies expressed on the level of populations, tetraploid and octoploids cannot be reliably distinguished morphologically and they are not taxonomically classified formally here.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 153 , 231–242.     

Karyomorphology of the endangered Trigonobalanus doichangensis (A. Camus) Forman (Fagaceae) and its taxonomic and biogeographical implications

Cytological studies were carried out for the first time on five populations of Trigonobalanus doichangensis in China and Thailand. In all populations, the pattern of interphase nuclei was of the simple chromocentre type, the mitotic prophases were of the proximal interstitial type and chromosome numbers were 2 n  = 2 x  = 14. Two B chromosomes were commonly observed at prophase and prophase–metaphase, but rarely at metaphase. Karyotype variation among the populations at the diploid level was limited, but there were some distinguishing cytological characters. Based on the comparison of all the available data on cytology, taxonomy, phytogeography and molecular systematics related to the genus Trigonobalanus , we recommend that the three species of Trigonobalanus comprise the subfamily Trigonobalanoideae and that the genus should not be segregated into three monotypic genera.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 321–330.     

Origins, establishment and evolution of new polyploid species: Senecio cambrensis and S. eboracensis in the British Isles

Two new polyploid species of Senecio have originated in the British Isles in recent times following hybridization between native S. vulgaris (2 n  = 40) and introduced S. squalidus (2 n  = 20). One of these is the allohexaploid S. cambrensis (2 n  = 60), the other is the recombinant tetraploid S. eboracensis (2 n  = 40). We review what is known about when and how each species originated, and their reproductive isolation from parents due to high selfing rates. We also review evidence that suggests S. cambrensis may have undergone rapid genome evolution since its origin, and comment on the risks of extinction to each species due to chance factors operating during the early establishment phase. The discovery of both species soon after their origin provides an unparalleled opportunity to examine two different but related forms of speciation following hybridization between the same parent species. Further detailed study of the ecology and genomics of S. cambrensis and S. eboracensis will help improve our understanding of the process of polyploid speciation in plants.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 467–474.     

Cytological studies on the genus Holcoglossum (Orchidaceae)

The karyotypes of ten species of Holcoglossum (Orchidaceae), a highly endangered and diversified genus from China, were investigated to study the infrageneric relationships, biogeography, and speciation patterns in the Hengduan Mountains. The karyotype formulae of the studied species are as follows: 2 n  = 38 = 20m + 18sm in H. subulifolium , 2 n  = 38 = 22m + 16sm in H. amesianum , 2 n  = 38 = 26m + 12sm (6 SAT) in H. lingulatum , 2 n  = 38 = 26m + 12sm in H. wangii , 2 n  = 38 = 10m + 28sm in H. kimballianum , 2 n  = 38 = 14m + 22sm + 2st in H. flavescens , 2 n  = 38 = 24m + 12sm + 2st in H. rupestre , 2 n  = 38 = 14m + 20sm + 4st in H. sinicum , 2 n  = 38 = 16m + 14sm + 8st in H. weixiense , and 2 n  = 76 in H. tsii . The karyotypes of two tropical species, H. amesianum and H. subulifolium , are the most primitive in the genus, whereas those of four temperate alpine species, H. sinicum , H. rupestre , H. weixiense , and H. flavescens , are more advanced. H. tsii is a tetraploid and H. rupestr e may be one of its ancestors. The low frequency of polyploidy in Holcoglossum in the Hengduan Mountains region supports the conclusion that chromosome stasis during rapid speciation is common there.  © 2007 The Linnean Society of London. Botanical Journal of the Linnean Society , 2007, 154 , 283–288.