Karyological studies of four genera of theChloranthaceae

Karyological observations on 7 species and 2 varieties of 4 genera belonging to theChloranthaceae demonstrate the presence of three basic chromosome numbers within the family, i.e., x = 8 (Hedyosmum), 13 (Ascarina) and 15 (Chloranthus, Sarcandra). The karyomorphology ofChloranthus andAscarina is similar, whereasSarcandra andHedyosmum display unique characteristics. Both karyological aspects, i.e., chromosome number and karyomorphology, demonstrate remarkable diversity ofChloranthaceae and complex relationships between its genera. A distant affinity betweenChloranthaceae andPiperales is suggested.Presented at the XV International Botanical Congress Yokohama 1993, Symposium on Relationships and Evolution of Primitive Angiosperms: Multidisciplinary Approaches.     

Basic chromosome numbers of terrestrial orchids

The chromosome numbers of forty-one Brazilian species belonging to 11 genera of preferentially terrestrial orchids (subfamilies Cypripedioideae, Spiranthoideae, Orchidoideae, and Vanilloideae) were examined. Previous records for these subfamilies were reviewed in order to identify the ancestral chromosome numbers of terrestrial orchids. The variation observed within the subfamilies Spiranthoideae (2n=28, 36, 46, 48 and 92), and Orchidoideae (2n=42, 44, ca. 48, ca. 80, 84, and ca. 168) was similar to that previously reported in the literature. In the subfamily Spiranthoideae, some species of Prescottia (subtribe Prescottiinae) and some genera of Spiranthinae showed a bimodal karyotype with one distinctively large pair of chromosomes. The analysis of chromosome numbers of the genera in subfamilies revealed the predominance of the polyploid series 7, 14, 21, 28, 42 with a dysploid variation of ±1 in each ploidy level. These results suggest that the basic chromosome number of terrestrial orchids is x₁=7 for the subfamilies Spiranthoideae and Orchidoideae, as well as other Epidendroid orchids, and that the majority of the genera are composed of palaeopolyploids.     

Zur systematischen Stellung der GattungProckia: Karyologie und Epidermisskulptur im Vergleich zuFlacourtia (Flacourtiaceae),Grewia (Tiliaceae) und verwandten Gattungen

Detailed analyses of karyology and leaf morphology do not support relationships betweenFlacourtiaceae andTiliaceae. In spite of different chromosome numbers,Prockia (2n = 18),Flacourtia (2n = 22) andRawsonia (2n = 22) are very similar in karyomorphology, indicating a certain karyological uniformity withinFlacourtiaceae. Lacistema (2n = ca. 62) appears more isolated. On the other hand, theTiliaceae Grewia (2n = 18) andLuhea (2n = 36) have much in common and differ remarkably from the Flacourtiaceous genera. The salicoid leaf-teeth ofProckia are also found inIdesia, but never inTiliaceae. Epidermis ultrastructure reveals certain relationships betweenProckia andFlacourtia in contrast to the strongly differingGrewia. Idesia has a rare und unique epidermis sculpture. — Basic chromosome numbers and chromosomal evolution within theFlacourtiaceae are discussed.

     

Karyology of theScorzonera (Compositae) species from the Iberian Peninsula

A karyological study of 15 taxa ofScorzonera L. from the Iberian Peninsula has been made. The chromosome numbers found inS. hispanica var.pinnatifida, S. baetica, S. reverchonii, S. angustifolia, S. laciniata var.calcitrapifolia and var.subulata (2n = 14) are new. Diploid cytotypes with 2n = 14 and 2n = 12 prevail, andS. hispanica var.crispatula is the only taxon which exhibits autopolyploidy (2n = 14, 28). x = 7 is considered to be the base chromosome number within the genus, with x = 6 being derived from it by translocation. This and detailed karyotype analyses allow to group the Iberian Peninsula species ofScorzonera into three groups.     

Variation and Evolution of Karyotype Characters in Palm Subfamily Coryphoideae s.l.

Karyological data are presented for 13 genera of palm subfamily Coryphoideae s.l. Chromosome numbers of 4 species and of genus Guihaia (G. argyrata, 2n = 36) are new. Apart from the prevailing chromosome number of 2n = 36, subfam. Coryphoideae s.l. shows extreme heterogeneity with respect to chromosome size and morphology, organization of constitutive heterochromatin (C-banding, fluorochrome staining), interphase nucleus structures and prophase condensation patterns. Five karyologically differing groups of genera can be distinguished (Coccothrinax-group, Guihaia, Livistona-group incl. Sabal, Phoenix, and Bismarckia). Chromosome evolution probably has gone from medium sized to very small chromosomes with an average length of less than 1.5 μm; hc-distribution from evenly distributed throughout the karyotype to accumulated in few chromosomes; from simple banding patterns to complicated ones (hc-elaboration). Karyotypes with chromosomes of continuously decreasing size, similar morphology, and uniform prophase condensation probably gave rise to almost bimodal karyotypes with non-uniform, heteropycnotic chromosomal structures. Changes in the organization of interphase nuclei are corresponding. Karyotype differentiation is compared to major evolutionary events in floral and vegetative morphology of subfam. Coryphoideae s.l. Karyologically, genera Phoenix and Bismarckia are isolated and the relations to the remaining part of the subfamily are not clear.     

Karyology and systematics of the genusAmbavia and otherAnnonaceae from Madagascar

New chromosome counts and nuclei structures are reported forAnnonaceae species from Madagascar:Ambavia (2n = 14),Xylopia (2n = 16) andPolyalthia (2n = 18). This first generic count ofAmbavia and its nucleotypic parameters underline its long term isolation from the African continent and it should be regarded as an extremely distinct member of the basic stock of AfricanAnnonaceae. Some karyological similarities are found with the African generaCleistopholis (2n = 14) andUvariopsis (2n = 16) and the AmericanTetrameranthus (2n = 14, 28). The karyology ofXylopia is completely in line with previous results from the Palaeo- and Neotropics.Polyalthia has 2n = 18, and x = 9, probably the only base number within the whole genus. Fluorochrome and Giemsa-C-band patterns are identical with different congeneric species.Dedicated to Prof. DrElisabeth Tschermak-Woess on the occasion of her 70th birthday.     

Cytogenetics of protoplast cultures of Brachycome dichromosomatica and Crepis capillaris and regeneration of plants

Summary Callus derived protoplasts of Brachycome dichromosomatica (2n=2x=4) and Crepis capillaris (2n=2x=6) have been regenerated into karyologically normal plants, i.e. plants without visible alterations of the diploid chromosome set. However, metaphase analysis of protoplast cultures derived from both callus as well as mesophyll cells showed karyological changes in the overwhelming majority of cells in both species leading to multinucleated, polyploid and aneuploid cells. Furthermore, callus derived protoplasts sometimes exhibited changes at the chromosome level as indicated by translocations. The vast majority of aberrant karyotypes arose from failures during mitosis and cytokinesis, pointing to inadequate microtubules as a possible underlying cause. Karyological events of the kind described herein greatly affect the plating efficiency of isolated protoplasts and the viability of protoplast derived calli. Plant regeneration, although demonstrated in this study for the first time in both species, seems to be limited to rarely occurring, protoplast-derived colonies with a relatively stable genome. Our experiments, performed with chromosomal model species, emphasize the need for controlled, non-mutagenic culture conditions.     

The karyology of some neotropicalStyracaceae

Chromosome numbers and karyomorphological characters have been investigated inPamphilia andStyrax (Styracaceae). Counted for the first time in the genus, two species ofPamphilia were found to have 2n = 16. The twoStyrax spp. investigated share withPamphilia the same chromosome number, a peculiar condensation behaviour of the chromosomes (Fig. 1a–c) and the same type of semi-reticulate interphase nucleus, results which indicate a close relationship of the two genera. The base number inStyracaceae is probably x = 8 (2n = 2x = 16) with stabilized triploids inHalesia andPterostyrax (2n = 3x = 24). A preliminary comparison withSapotaceae andEbenaceae does not allow a general karyological characterisation of the orderEbenales.     

Chromosome analysis ofHaemanthus andScadoxus (Amaryllidaceae)

Chromosome analysis of nine species ofHaemanthus (2n = 16) and four species ofScadoxus (2n = 18), using conventional stains, Quinacrine fluorescence and C-banding, has shown that the two genera do not possess significant amounts of constitutive heterochromatin. The two genera are closely related and differ in respect of a translocation which has resulted in the dysploid reduction in chromosome number from 2n = 18 inScadoxus to 2n = 16 inHaemanthus.     

Vergleichende Karyologie der Gräser-SubtribenAristaveninae undAirinae (Poaceae — Aveneae)

The chromosome numbers of nearly all species of the grass subtribesAristaveninae andAirinae from Europe and northern Africa are presented. Among theAristaveninae the genusAristavena has 2n = 14 chromosomes, whereasDeschampsia forms a polyploid series with the basic number x = 13. In the subtribeAirinae the basic number x = 7 predominates.Avenella includes a polyploid series up to dekaploidy, whilst the lowest diploid value so far known in grasses — caused by descending dysploidy — exists in the annual generaAiropsis andPeriballia with 2n = 8.From both subtribes 12 different karyotypes are described and depicted as idiograms. The basic karyotypes ofCorynephorus, Periballia andVahlodea differ from each other by different chromosome length. SAT-chromosomes in theAirinae vary somewhat. Some marker chromosomes eludicate phylogenetic relationships. Amphiplasty appears in various genera and was studied particularly in the amphidiploidAira caryophyllea. Karyological and genomatic trends are considered in relation to evolutionary strategies of annuals and perennials.The nuclear DNA content of some species has been determined cytophotometrically. In subtribeAirinae a positive correlation exists between chromosome volume, pollen diameter, and DNA content. A comparison of the duration of microsporogenesis and microgametogenesis in annual and perennial species with their nuclear DNA content has shown that a primary nucleotypic influence is not recognizable.

     

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.     

Chromosomal evolution ofGentiana andJaeschkea (Gentianaceae), with further documentation of chromosome data for 35 species from western China

Chromosome numbers were recorded for 63 populations of 34 species belonging to the genusGentiana from the high altitude regions of western China. Counts for 22 species were reported for the first time and new numbers were found forG. heleonastes (2n = 36),G. prattii (2n = 20) andG. pseudoaquatica (2n = 40). Incorporating previous data, a complete series of gametic chromosome numbers from n = 6 to 24 and 26 was established for the genus, suggesting rapid karyotypic evolution by a combination of dysploidy and polyploidy. The cytotype 2n = 20 is proposed as the ancestral type in sect.Chondrophyllae s. l. The chromosome number 2n = 16 was found forJaeschkea microsperma for the first time which, with previous reports of 2n = 18, 20 and 22, indicates thatJaeschkea is a typically dysploid genus.     

Variation and geographical distribution of ploidy levels inPennisetum sectionBrevivalvula (Poaceae) in Burkina Faso,Benin and southern Niger

Pennisetum sect.Brevivalvula is a species complex characterized by polyploidy and apomixis. Ploidy level was assessed by DAPI-flow cytometry for 304 plants of the section, originating from Burkina Faso, Benin and southern Niger. The results were confirmed for 54 plants based on chromosome counts. The samples show four euploidy levels (with x = 9) distributed among five species:P. hordeoides (2n = 36, 54),P. pedicellatum (2n = 36, 45, 54),P. polystachion (2n = 18, 36, 45, 54),P. setosum (2n = 54), andP. subangustum (2n = 18, 36, 54). The geographical distribution of these ploidy levels seems related to major vegetation zones present in Africa. Diploid populations ofP. polystachion andP. subangustum were found in the Banfora area, in Burkina Faso.     

Chromosome numbers, karyotypes and nuclear DNA contents from perennial polyploid groups ofCerastium (Caryophyllaceae)

Somatic chromosome numbers have been determined for the followingCerastium taxa:C. eriophorum (2n = 36),C. alpinum (2n = 72),C. transsylvanicum (2n = 108),C. arcticum (2n = 108),C. latifolium (2n = 36),C. carinthiacum (2n = 36),C. banaticum (2n = 36),C. arvense subsp.glandulosum (2n = 36),C. arvense subsp.arvense (2n = 72) andC. fontanum (2n = 144). Karyotypes of three diploid species (C. eriophorum, C. banaticum andC. latifolium), belonging to three different taxonomic groups, were analysed and found to be similar. The relative nuclear DNA contents of all taxa were determined by flow cytometry and, for five species, also by Feulgen cytophotometry. The values obtained by the two methods are similar. A comparison of nuclear DNA contents among diploids shows that values differ significantly between different taxonomic groups, and are correlated with average chromosome size. Within closely related polyploid groups nuclear DNA amounts increase from 2x- to 4x- and 6x taxa as 1 : 1.4 : 2.4 in theC. alpinum complex, whereas DNA amounts are doubled comparing 2x- and 4x-subspecies in theC. arvense complex.     

Karyological notes onCentaurea sect.Acrocentron (Asteraceae)

The karyology ofCentaurea sect.Acrocentron is surveyed. 19 chromosome counts on 8 species are reported; those onC. acaulis, C. crocata, C. galianoi, C. pubescens, andC. malinvaldiana are new. The basic chromosome numbers of the section are x = 11 and x = 10. Karyological arguments have been used to show that evolution was from x = 11 to x = 10. This is supported by biogeographical data. Two main centres of diversification of sect.Acrocentron were studied from that point of view: the East and the Southwest Mediterranean region.     

Karyological studies onGentiana sect.Chondrophyllae (Gentianaceae) from China

Nineteen populations of fifteen species ofGentiana sect.Chondrophyllae from China were observed cytologically.Gentiana alsinoides, G. anisostemon, G. asterocalyx, G. exigua, G. heterostemon, G. intricata, G. praticola, G. pseudoaquatica, G. spathulifolia, andG. subintricata all had the same chromosome number of 2n = 20 (or n = 10), whereasG. piasezkii had 2n = 36,G. squarrosa 2n = 38,G. prattii 2n = 18,G. aristata 2n = 14 (n = 7), andG. heleonastes 2n = 12. All these chromosome numbers are documented here for the first time, except forG. squarrosa, where it is a new number report. The basic numbers of x = 6, x = 7 and x = 19 are new for the section. Karyotype analyses of some species revealed that, except for a few cases, the species examined mainly had metacentric chromosomes. 2n = 20 = 2m(SAT) + 18m was found to be the main type of karyotype for the species with 2n = 20. Chromosomal evolution and its mechanism in this section are also discussed.     

Chromosome banding and genome size differentiation inProspero (Hyacinthaceae): Diploids

Prospero is a Mediterranean autumn-flowering genus ofHyacinthaceae commonly classified inScilla asS. autumnalis andS. obtusifolia. Extensive dysploid and polyploid variation has been reported. In the present study 77 diploid accessions from the western to the eastern part of the area of distribution, the major part being from continental Greece and Crete, have been analysed for karyotype structure and, in part, for genome size. Methods employed were acetocarmine staining, Giemsa C-banding, fluorochrome staining mainly with chromomycin A₃/DAPI, silver impregnation, and Feulgen densitometry. Banded idiograms were established with a computer assisted karyotype analysis procedure. Chromosome numbers were 2n = 8 inP. obtusifolium, and 2n = 12 and 14 inP. autumnale s. l. Dispensable euchromatic chromosome segments and different types of B chromosomes occurred. Among the cytotypes with 2n = 14 two karyotypes from Turkey differed from each other and from the rest in form, position of the nucleolar constriction, and in genome size. The remaining accessions were similar in karyotype shape but three levels of genome size could be discerned, the highest (1C = 7.50 pg) being found on the Iberian Peninsula, an intermediate one on Corsica and Malta, and the lowest (4.27 pg) in the Aegean. The karyotype with 2n = 12 had an intermediate genome size, and that ofP. obtusifolium a relatively low one. Heterochromatin amount was generally low, but some karyotypes showed characteristic banding patterns. The relationship between the chromosome complements with 2n = 14, 12 and 8 is discussed on the basis of idiograms and DNA amounts.The authors respectfully dedicate this papers to emer. o. Prof. Dr.Elisabeth Tschermak-Woess on the occasion of her 80th birthday.     

Amounts of ribosomal DNA inAllium (Liliaceae)

Eight species ofAllium subgen.Allium sect.Allium have been studied at the cytological level by means of karyological analyses and at the biochemical level with regard to the proportions of ribosomal DNA. All the species have a basic genome of x = 8.A. sativum, A. commutatum, A. ampeloprasum, andA. vineale possess approximately 0.050% rDNA and two nucleolus organizer regions per basic chromosome set.A. sphaerocephalon andA. arvense have two nucleolus organizers, andA. amethystinum three nucleolus organizers per haploid (n = x) genome: the three species possess approximately 0.075% rDNA.A. acutiflorum has five nucleolus organizer regions per haploid genome and 0.121% rDNA. An attempt to relate these differences with functional and ecological characteristics indicates that evolutionary variation of rDNA proportions is not casual. Such data also can help to define systematic affinities and circumscribe infrageneric taxa.     

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.     

Chromosome numbers and taxonomic implications in the fern genusAzolla (Azollaceae)

Investigation of chromosome numbers of allAzolla species, and for the first time of hybrids, has been undertaken. Removal of wax from the leaf surface proved invaluable in achieving clear cytological preparations and providing unambiguous chromosome numbers. In contrast to previous records, the speciesA. pinnata, A. filiculoides, A. filiculoides var.rubra, A. caroliniana, A. microphylla, andA. mexicana were found to be 2n=44, andA. nilotica to be 2n=52. Several triploids (2n=66) and one tetraploid (2n=88) were identified. No geographical pattern could be observed in the distribution of triploids which probably derive from the function of unreduced gametes. The chromosome number of hybrids occasionally deviates from the diploid chromosome number (2n=44). The small chromosome size limits karyotypic analysis and only differences in overall chromosome size can be observed. Taxonomic implications of chromosome numbers and sizes are discussed.