Polyploidy and aneuploidy inOphrys,Orchis, andAnacamptis (Orchidaceae)

Studies on chromosome numbers and karyotypes in Orchid taxa from Apulia (Italy) revealed triploid complements inOphrys tenthredinifera andOrchis italica. InO. tenthredinifera there is no significant difference between the diploid and the triploid karyotypes. The tetraploid cytotype ofAnacamptis pyramidalis forms 36 bivalents during metaphase I in embryo sac mother cells. Aneuploidy was noticed inOphrys bertolonii ×O. tarentina with chromosome numbers n = 19 and 2n = 38. There were diploid (2n = 2x = 36), tetraploid (2n = 4x = 72), hexaploid (2n = 6x = 108) and octoploid (2n = 8x = 144) cells in the ovary wall of the diploid hybridOphrys apulica ×O. bombyliflora. Evolutionary trends inOphrys andOrchis chromosomes are discussed.     

云南宾川县鸡足山地区多星韭种群分化的研究

对鸡导山地区７个多星韭种群的生物生态学特性进行了比较全面的研究。结果表明;鸡足山地区的多星韭有二倍体和四倍体２种倍性。多星韭二倍体比四倍体更能忍受较恶劣的环境条件。二倍体多星韭生境单一,种群分化不明显;四倍体多星韭生境多样,种群间变异丰富,分化强烈。     

Taxonomic studies of theMuscari botryoides complex in Hungary

The ploidy level and karyotype ofMuscari botryoides (s.l.) samples from Hungary (25 localities) and Romania (1 locality:locus classicus ofM. transsilvanicum) were determined. The Romanian sample proved to be diploid (2n=18), while in Hungary both diploid and tetraploid (2n=36) populations occurred. The karyotypes of all diploid populations were similar: 2 pairs of long acrocentric (one of them usually with satellites) + 3 pairs of medium-sized submetacentric-metacentric + 4 pairs of short ± metacentric chromosomes. All diploid populations in Hungary can be identified asM. transsilvanicum. There is no reason to support the taxonM. botryoides subsp.hungaricum because it does not differ from the sample collected at thelocus classicus ofM. transsilvanicum (Romania, Sibiu-Gu?teri?a) in any of the characteristics mentioned in its protologue. Its karyotype also corresponds to that ofM. transsilvanicum. Contrary to the former assumptions, the tetraploidM. botryoides is also native to Hungary. The tetraploid karyotype seems to be somewhat of a duplication of the diploid one. Morphological characters used in the identification keys are not suitable for unambiguous separation of the taxa mentioned above, though morphometric analyses revealed some quantitative differences between diploids and tetraploids. Their separation on species level can only be supported by the supposed reproductive barriers caused by different ploidy level and chorology. In HungaryM. transsilvanicum is restricted mostly to the Eupannonian Region, the Mecsek and Villány Mts.M. botryoides does not occur in the Eupannonicum, instead it inhabits the subatlantic hilly W and SW part of Hungary and the Northern Mountain Range. The latter territory (including also the Slovak localities) seems to be the easternmost extension of the area ofM. botryoides.     

Cytogenetic studies in the genus Zea

Summary The nuclear DNA amount and the heterochromatin content in species and hybrids of Zea were analyzed in telophase nuclei (2C) of the root apex of germinating seeds. The results revealed significant differences among taxa and also among lines and races of maize. The hybrids between Z. mays ssp. mays x Z. mays ssp. mexicana (2n=20), Z. diploperennis x Z. perennis (2n=30), and Z. diploperennis x Z.perennis (2n=40) showed DNA content intermediate between that of the parents. The number of chromosomal C-bands and the proportion of the genome comprising C-band heterochromatin were positively related to genome size. In the different lines and races of maize studied, there was a positive correlation between genome size and the interval from germination to flowering. Octoploid Z. perennis (2n=40) showed the smallest DNA content per basic genome and the smallest heterochromatic blocks, suggesting that the DNA lost by this species consisted mainly of repetitive sequences. Considering that the extant species of Zea are tetraploid (2n=20) and octoploid (2n=40) and that the ancestral diploids are extinct, any consideration of the direction (increase or decrease) of the DNA change would be entirely speculative. The extant species could be the product of natural and artificial selection acting on different genotypic and nucleotypical constitutions at the diploid and/or tetraploid levels.     

Karyological variation in the group ofMyosotis alpestris (boraginacea)

A total of 6 population samples ofMyosotis stenophylla Knaf, a rare species showing great ecological disjunction in its distribution, were examined to clarify the present status of its karyological variation. In order to elucidate relationships between lowland tetraploid populations ofM. stenophylla and diploid and tetraploid montane populations ofM. alpestris F.W. Schmidt, four population samples ofM. alpestris were also examined. The karyotypes of all populations ofM. alpestris s.l. studied were highly asymmetrical and heterogeneous, being composed of metacentric, submetacentric, subtelocentric and satellited acrocentric chromosomes. The karyotype formula for haploid chromosome set was established: n=x=12=6m+2sm+3st+1t^SAT. Multivariate analysis based on chromosome length and shape showed significant differences between diploid and tetraploid forms ofM. alpestris s.l. Four numerical parameters, used to characterize the karyotype ofM. stenophylla, revealed significant differences between populations on serpentine and on non-serpentine substrates. In addition, the noticeable affinity of the karyotype of non-serpentine populations to that ofM. alpestris tetraploids has been shown by means of discriminant analysis. These data suggest that the unique features of serpentine play an important role in the origin of karyotypic differentiation within populations ofM. stenophylla.     

Karyosystematic studies on threeCrepis species (Asteraceae) endemic to Greece

This work examines the cytogeographical distribution, the morphological characters, and the karyotypes of threeCrepis species endemic to Greece (C. sibthorpiana, C. incana, andC. heldreichiana). C. sibthorpiana is diploid (2n = 2x = 8),C. incana is diploid (2n = 2x = 8) and tetraploid (2n = 4x = 16, 17), andC. heldreichiana is always dekaploid (2n = 10x = 40). The Giemsa positive bands, usually pairs of dots, are mainly centromeric inC. incana, while they are terminal inC. sibthorpiana (on the short arm of all chromosomes) and inC. heldreichiana (on both arms of all chromosomes). Intercalary C-bands are scarce and usually variable within karyotypes, individuals, and species. The most variable karyotype both in Feulgen and Giemsa preparations is that ofC. incana, in which also supernumerary chromosomes were observed, which are polysomic to standard set members. On the basis of morphological and karyological data the evolutionary relationships among the threeCrepis taxa are discussed.     

Cytotaxonomic study of genusHymenasplenium (Aspleniaceae) in Xishuangbanna, Southwestern China

The gametic chromosome numbers of sevenHymenasplenium (Aspleniaceae) species from Xishuangbanna, Yunnan Prov., China, were investigated. All the examined individuals ofH. obscurum, H. cheilosorum andH. latipinnum were sexual diploids with n=39 chromosomes. Intraspecific cytological variation was found inH. excisum, which has a sexual diploid (n=39) and a tetraploid (n=78). Only a triploid apogamous cytotype (n=ca.117) was found inH. laterepens. Hymenasplenium apogamum showed the most complicated intraspecific variation and included a sexual diploid (n=39), a sexual tetraploid (n=78) and an apogamous triploid (n=ca.117). This work reports for the first time the sexual diploids ofH. cheilosorum andH. apogamum, which are only apogamous elsewhere in east Asia, Himalayas and Indochina. These results may indicate that this area is one of the diversity centers ofHymenasplenium. Most of the above species have chromosome numbers based on x=39. In contrast,H. costarisorum contains a sexual diploid (n=36) and a sexual tetraploid (n=72), indicating that its basic number is x=36.     

Cytotaxonomy and breeding system of the genusBiscutella (Cruciferae)

Chromosome counts were determined for 46 populations ofBiscutella representing 28 taxa. The genus was found to contain diploid taxa with 2n = 12, 16 and 18, tetraploid taxa with 2n = 36 and hexaploid taxa having 2n = 54.B. laevigata L. s. l. consists of diploid and tetraploid populations which are poorly differentiated morphologically. TetraploidB. laevigata s. l. and hexaploidB. variegata Boiss. & Reuter (s. l.) are characterized by chromosomal instability. The variation in chromosome numbers and the occurrence of polyploidy is discussed in relation to the taxonomy of the genus. An investigation of the breeding system showed that most of the annual species were self-compatible and partly inbreeding and most of the perennial species self-incompatible and, therefore, outbreeding, while one annual species,B. cichoriifolia Loisel., showed both systems.     

Alternation of nuclear phase in the filamentous basidiomycete,Helicobasidium mompa

Variation in the number of nuclei and cellular ploidy were observed in eight strains ofHelicobasidium mompa. The basidiospores, single-spore isolates and field-isolated strains were all dikaryons. The cellular ploidy, which was assessed by analyzing the fluorescence emitted by DAPI-stained nuclei, was unstable: monokaryotic strains derived from the original dikaryotic strains by successive subcultures were mainly tetraploid, although the original dikaryon was in most cases diploid. On the other hand, a dikaryotic strain derived by treatment with benomyl was haploid. These results suggest that diploid dikaryon is a normal nuclear phase ofH. mompa in nature, and the alternation of ploidy may be due to a feature of the mating system of this fungus.     

Genetic and chromosomal variation inPetunia hybrida plants regenerated from protoplast and callus cultures

Plants regenerated from callus cultures derived from leaf discs and mesophyll protoplasts ofPetunia hybrida cv. Rose of Heaven exhibit a high frequency of genetic and chromosomal variation. Of twelve leaf disc-derived plants examined, only three had the normal diploid chromosome number (2n=14) while seven were tetraploid and two were aneuploid (16 and 27 chromosomes). Of seventeen plants derived from two protoplasts, none had the diploid chromosome number. Most had 28 chromosomes, one 29, two 27, one 26 and one had variable numbers (14–28) in different root tip cells. In all cases aneuploidy was associated with developmental abnormality. In addition, heritable differences in growth, morphology and flower pigmentation were observed in callus-derived tetraploids and diploids, including one diploid which differed from parent plants in at least four characters. These results are discussed in terms of the importance ofPetunia in genetics research and for studies of somaclonal variation.     

Serpentine and polyploid differentiation withinGalium pumilum agg. (Rubiaceae) in Eastern C. Europe

The local differentiation of a model group,Galium pumilum agg., was studied in serpentine versus non-serpentine habitats in the Czech Republic and adjacent regions in Austria, Germany and Poland. Serpentine habitats form ecologically distinct islands within the landscape; local micro-evolutionary processes may be important there, both because of small population sizes and the strong selection effects of the metal-rich soils. TheGalium pumilum agg. is a group of taxa showing typical karyological and ecological differentiation; the following species and cytotypes were studied:Galium pumilum Murray (2n=8x=88),G. valdepilosum Heinr. Braun (2n=2x=22, 2n=4x=44),G. sudeticum Tausch (2n=4x=44) andG. austriacum Jacq. (2n=4x=44). The karyological and taxonomic investigation showed that serpentine versus non-serpentine habitats do not play an important role in the differentiation of the species studied. (1) The examined populations ofG. pumilum Murray were homogeneous in chromosome numbers, belonging to the octoploid (2n=88) cytotype only. (2)G. valdepilosum consists of two cytotypes. Both of them occur on and off serpentine sites, but they show pronounced East-West distributional difference. (3)G. sudeticum occupies special localities on serpentine in western Bohemia, which are geographically isolated from its nearest localities in the Krkono?e Mts. The plants coming from both localities belong to the tetraploid cytotype. (4) A highly polyploid plant (2n=12x=ca. 132) from theG. pumilum group was found on serpentine. From the methodological point of view, pollen size turned out to be reliable only for distinguishing octoploids from diploids and tetraploids, but it is less suitable for separating the latter two ploidy levels. The occurrence ofG. austriacum is reported for the Czech Republic for the first time with certainty. This record extends the known distribution area ofG. austriacum in the NW direction.     

Phenotypic differentiation of peripheral populations of Santolina rosmarinifolia (Asteraceae)

Phenotypic differentiation of two tetraploid (2n = 4x = 36, 36+1B, 36+2B) populations of Santolina rosmarinifolia geographically isolated from diploid populations was investigated. The karyotype was relatively homogeneous, meiosis was regular and pollen was fertile in both cytotypes. An autopolyploid or allopolyploid origin for tetraploid cytotypes is discussed. Overall, 80.82% of all variance in achene weight, time t₀, t₅₀ and t₉₀ of germination and accumulated germination rate was due to achene age at each ploidy level. Partition of the total phenotypic variance showed that there was extensive variation between ploidy levels. The mean of morphological characters was generally higher in polyploids. For diploid cytotypes, flower number, achene production and fruiting percentage were significantly higher than for tetraploid cytotypes. Cluster analysis indicated that the patterns of seedling morphology and development were similar in three diploid individuals and several tetraploids; the same analysis showed high similarity between diploid individuals of the natural populations, whereas tetraploid individuals showed high dissimilarity among themselves and with diploid individuals. Multiple correspondence analysis and logistic regression analysis indicated that qualitative characters contribute strongly to cytotype differentiation. The results support recognition of the tetraploid cytotypes at the subspecies level. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 650–668.     

A Complementary Method for Production of Tetraploid Crassostrea gigas Using Crosses Between Diploids and Tetraploids with Cytochalasin B Treatments

We present a new method to produce tetraploid Crassostrea gigas by cytochalasin B inhibition of polar body 2 expulsion in diploid females crossed with tetraploid males. This offers a means of direct introgression of genetic characters from selected diploid to tetraploid lines, avoiding a triploid step. Offspring larval ploidy shifted over time and depended on size, with tetraploids more frequent among the smaller larvae and triploids among the large. Viable tetraploids were found at 4 and 6 months, indicating the technique was successful. The possibility that gynogenesis occurred was tested by microsatellite analysis to confirm the presence of paternally inherited alleles. These were present in all animals of the 2n × 4n + CB (female first) cross. However, a 4n × 2n + CB cross produced triploids, including some gynogens. Our method illustrates for the first time that diploid C. gigas eggs, if selected for large size, can give viable tetraploid offspring.     

A taxonomic study of the genusCalamagrostis on Mount Yakeishidake

Populations of seven species ofCalamagrostis growing on Mt. Yakeishidake were studied from a viewpoint of taxonomy. Four of them (C. sesquifolia, C. fauriei, C. matsumurae, C. gigas) were composed of tetraploid plants with 2n=28 and high pollen fertility.C. matsumurae andC. gigas had sympatric contacts, but no sign of their hybridization could be detected. The population ofC. sachalinensis on this mountain included hexaploids (2n=42) and octoploids (2n=56), and no obvious morphological or ecological differences could be found between them. The population ofC. sachalinensis was estimated to include various ecological races which may be continuously graded. InC. langsdorffi, only octoploid plants were found. Plants with 2n=56+0?1B were found in the population ofC. hakonensis. The pollen features of the collections ofC. langsdorffii, C. sachalinesis andC. hakonensis showed that apomictic seed formation may be more or less developed in them. Populations of these species on Mt. Yakeishidake were clearly separated morphologically. It was concluded that the populations of the seven species examined each have a unity and that strains ofC. langsdorffii, C. sachalinensis andC. hakonensis found on Mt. Yakeishidake are confined to those of a derived type.     

Karyological and chemotaxonomical studies of the hybridPelargonium incarnatum ×P. patulum (Geraniaceae) and its parents

Pelargonium incarnatum is a tetraploid species (2n = 40) andP. patulum is diploid (2n = 22). A natural hybrid, collected at the same locality as the parent species, has 2n = 42 chromosomes. The meiosis of the hybrid is practically normal and its pollen fertility corresponds to that ofP. incarnatum. The flavonoid patterns of the parent species and the hybrid are very similar. The origin and phylogenetic implications of this intersectional hybrid are discussed.     

Untersuchungen zur Karyologie und Mikrosporogenese vonPelargonium sect.Pelargonium (Geraniaceae)

The chromosome numbers of the 24 species of sect.Pelargonium were determined from field collected and cultivated plants of known localities in S. Africa. Twelve species are diploid (2n = 22), eight tetraploid (2n = 44), one hexaploid (2n = 66), and three octoploid (2n = 88). The chromosome numbers correlate well with the proposed subdivision of sect.Pelargonium. Its chromosomes are relatively small (1.0–1.5 µm) in comparison to most of the other sections, and its diploid karyotype is considered to be primitive. The occurrence of the basic number x = 11 in this section, in other sections of the genus, and in related genera (Monsonia, Sarcocaulon) leads to the conclusion that x = 11 probably is basic for the whole genus. — The pollen meiosis, microsporogenesis and pollen fertility of the diploid species is normal, with the exception of one, possibly young taxon from the Greyton Nature Reserve. The tetraploid species could be of autoploid origin, the higher polyploids exhibit a mixed auto-alloploid nature. — The 20 diploid and tetraploid species have a relatively small distribution range, most of them occur in the SW. Cape Province of South Africa. This area may therefore be considered as the centre of origin of the genus. Three of the four high polyploid species occupy rather large areas.

Untersuchungen zur Karyologie und Mikrosporogenese der GattungPelargonium, 1.     

A biosystematic study ofValeriana officinalis (Valerianaceae) distributed in Bulgaria

Valeriana officinalis L. is an extremely polymorphic polyploid complex. On the basis of morphological, cytological, and phytochemical investigations of Bulgarian populations ofV. officinalis the two subspeciesV. officinalis subsp.officinalis (2n = 14, 28) andV. officinalis subsp.collina (2n = 14, 28) were each subdivided into diploid and tetraploid cytotypes.     

Chromosome numbers of Western Australian species ofVillarsia (Menyanthaceae)

Chromosome numbers are reported for eight of the nine Western AustralianVillarsia species.Villarsia albiflora, V. calthifolia, V. capitata, V. congestiflora, V. lasiosperma, V. latifolia, andV. violifolia are diploid with n=9. Five populations ofV. parnassiifolia are diploid and three are tetraploid (n=18). The morphological, ecological, and breeding-system diversity of the Western Australian species is largely not associated with the tetraploidy or hexaploidy that characterizes otherVillarsia species in eastern Australia and South Africa. The majority of Western AustralianVillarsia species are restricted to the high rainfall zone of southwestern Western Australia, where favorable climatic and edaphic conditions may have existed since mid-late Tertiary times.     

Cytological and hybridization studies inLeucanthemum (Compositae—Anthemideae) from North Africa

A cytological survey ofLeucanthemum species in North Africa has shown that they are all diploid with a somatic chromosome number of 2n = 18. New counts are reported for 8 species and 1 subspecies. 11 taxa were used in a crossing programme and the results show a good agreement between phenetic distance based on morphological characters and genetic differentiation as expressed in the ability of the species to hybridize. A strong barrier to gene exchange exists between European and North African species. Bagging experiments showed that the North African species comprise a self-incompatible group of cytogenetically related species.